Thanks John as a sparky in a former life, still registered, I can say you pretty much nailed it for the lay person! I had my mental list and you managed to address the lot. Even the duty cycle issue. well done!
First thing I did was redo all the electrical on my boat, aadd solar and batteries, and bring it up to current specs. We have to get a certificate for gas, elecrical and a seaworthy survey every five years for insurance purposes. That's an out of the water inspection too. I hate to think og how many homes haven't been looked at or have had DIY additions without seeing a licenced sparky.
@@grantleyhughes - hoe many extension cords with no tags -uggghh.. or custom replaced ends, shudder (actually the ones with bare single insulation on pulled ends much more worrying (that old cloth insulation, all frayed - lol...
John, you may also consider doing a video on the maintenance of home compressors or lack there of. Plenty of DIY'ers fail to remove the moisture from the tank after use and after a few years the rust in the tank can cause a huge explosion similar to a bomb going off. take a look ruclips.net/video/sm_FJ6Pat4I/видео.html
@@TheReal1953 You should google "compressor explosion". Once the rust has compromised the tank, the pressure will build up in the tank and then the tank lets go.
@@EricBanner571 I would think that's a function of a humid environ and poor maintenance. In all the yrs around compressors and dumb people, I've never seen this occur. What I DO see is tanks starting to leak at the bottom because of trapped moisture.
@@Conservator. Just go talk to your WHS officer, I'm sure they've got multiple PowerPoints relating to electrical appliances and not using extension leads with them. I know ours does.
John is spot on again my dad was a electrical engineer and I've worked in electrical wholesale and as a kitchen/furniture maker, I have 3phase connection to my house so its great for welders, compressors and aircon but do do tend to use smaller 10a welders and compressors more often than my bigger older ones and nearly all my power tools that my dad passed on to me have upgraded cords along with a few of them amphibian type 15a to 10a cords with a rcd or breaker in them that were home made long before you could buy them amphibian leads
Great video John. The air compressor situation also explains problems you get with extension cords in general. Like why does my power tool lack power using 100m of extension cord ? 😀 Using a voltage drop calculator and some research, I got the voltage drops for various extension cords. This might help people get an idea of which cable and length to use. For the 2.75 hp compressor, 230 VAC at the plug, and a power factor (think efficiency) of 0.95, there will be 9.39 A current draw. For every 10m length of - Standard 10A extension cords, 1mm² = 4.84 VAC drop Extra Heavy Duty 10A* and Standard 15A extension cords, 1.5mm² = 3.10 VAC drop Extra Heavy Duty 15A and 10A^ extension cords, 2.5mm² = 1.69 VAC drop Remember these numbers are at nearly full capacity (10A) of the power socket, if you are using less current then the voltage drops will be proportionally less. Half the current (5A) = half the voltage drop. * Not all Extra Heavy Duty 10A extension cords have 1.5mm² cable. Always check. ^ Only found Delta brand had 15A and 10A, 2.5mm² extension cables. There may be others. Calculator I used - www.jcalc.net/voltage-drop-calculator-as3008 How much voltage drop can you have? The allowed voltage at the power socket in Australia is 216 VAC to 253 VAC. If you get the average 230 VAC at the socket then you shouldn't have more than 10 VAC drop, giving you 220 VAC at the end of the extension cord. So for close to 10A draw from the power socket with 230VAC or more - Standard 10A extension cords, 1mm² = max 20m extensions Extra Heavy Duty 10A* and Standard 15A extension cords, 1.5mm² = max 30m extensions Extra Heavy Duty 15A and 10A^ extension cords, 2.5mm² = max 50m extensions Again if you are drawing less current you can use a longer extension. Standard 10A extension at 5A = max 40m extension. One last thing is you may need to factor in the distance of the power socket from the meter box. That length of wire will also have a (smaller) voltage drop that will affect the total and your extension cable length. Hope this helps as guide.
The allowed voltage drop in the run from the meter box to the socket outlet is already subsumed in what you quote as the allowable voltage range at the socket outlet - 216-253V. It certainly is in my country, which I expect substantially borrows from the same IEC standards as yours. So as a user of an electrical installation, you shouldn't have to worry about that. (But your electrician who installed it, should have.)
@@bpj1805 yes for fixed wiring it has been calculated. BUT for extension leads it has not. our nominal voltage range is 220 to 250 volts. most will read around 238v rms at the outlet under no load conditions
The thing that both you and John overlooked is that electric induction motors draw 3 to 5 times their rated running current when they are starting which drops the voltage even more. Granted, this is only for a very short period of time, but it does need to be considered.
@@BryanTorok True. Looking at the instructions for the Stanley Twin Stack Air Compressor , the compressor has a rating of 2100W, around 9.5 Amps. It also states Minimum Generator Size of 5000W. From this I would surmise that the peak (startup) current could not be much more than double. Otherwise the generator would stop/stall or a mains breaker would trip. There may be a soft start circuit on the motors to reduce the startup current.
@@tonyonofrio1147 Typical (not inverter) generators have a peak (short term) rating of 20% to 25% more than the constant running current in part to allow for motor start up current. Inverter generators are not that generous.
But isn't it so much easier in the UK? Our power points are all the same, there's no thick and thin earth pins to worry about. Ring fused at 32amps radial fused at 16-20 amps. 3hp motor would be hard wired into the mains circuit. The only real problem, yet again, are humans who tend to plug anything in at any time, without looking at the fuse in the plug. The amount of power cords going to computers, table lights, battery chargers, etc, fitted with a 13amp fuse is frightening!!
We don't have shitty extension cables like that in the UK. Our plugs, sockets and extensions are all rated at 13A. A half decent welder gets pretty near to that limit in the UK so I don't know what they do down under. I put 16A commando sockets in my garage for this stuff.
@@PJ-om2wq My _WHOLE_ workshop runs off an extension lead from the house - can't get a reliable electrician to even keep an appointment round here - gave up! I run welder/compressor and lights simultaneously through a cheap surge protection switch block - never tripped out.
You are spot on, every point, and a well explained video for the layperson. Sadly induction motors are very sensitive to voltage drop and this advice carries equally through to things like brick saws etc. Universal motors like grinders and drills are immune to drop, other than a reduction in speed and torque of course. In the real world, these compressors work quite happily on reasonable lengths of extension cable as long as they are at least 1.5mm and as you rightly point out, its just a 400 dollar investment, not exactly world shattering. In my own fat cave, there is a 5HP unit running from a dedicated outlet on a sub panel but I do also own a cheap 2.5HP unit and its been known to run at the end of 25 meters of half decent extension cable without any problems what so ever. The big compressor is for shop air and heavy use, the little compressor is for portable use around the farm, haven't killed a motor yet but have had many mechanical failures on the cheap units. Just my 2 cents worth, others mileage may vary.
Thank you, Sir, that was as good as it gets for a master class on electricity and compressors. I'm here in New York City, USA and truly enjoyed your teaching style and depth of knowledge. Awesome!
I find you very entertaining, John. As an American, it's refreshing to hear your Aussie idioms and you've taught me a lot. My wife is tired of me binging your vids today. See you soon.
Thanks mate - I fall over at 'inductance'. (I know what induction is...) kVA vs kW is also a grey area for me. The stuff in this video was pretty basic - all homeowners should know it. Appreciate you watching.
@AutoExpertJC To John, was so right. As you explained so well, as being as ex spark, most wiring in most wire in most home in Australia is 2.5 cm for 10 GPO outlets But most new home have 4 or more power outlet in each room. As I put out to most poaple, the RCD can up have to 20 point points. That just to start with and all doubt power point points. It doesn't stop there, as many have power points for the computer,, modern, print er and got into 6 outlet powerboats. That's not for study, but as well for lounge room the TV, top box and sound system. As you have kitchen microwave most of them 1200 watt, dishwasher , and exhausted fan. So most homes have 10 RCD and about 6 MCB for air-conditionings, hotwater service or heatpump now got RCD as work like aircon. As you was say you have 20 RCD with MCD. As most have 10 RCD for 2.5 cm wire. I have never been to you place, but having 20 Rcd on each breaker you most 4cm and had good electrician do wire. As most outdoor use 4cm wire, as light and power is on same cable. As you must have 40 power points or storage home. I read enjoyed your video. As love you to show why extreme come didn't color for different jobs. As one of your pet hates caravans using them in poaple back to live in. So can buy a RCDMCB cord so they kill them self or others. If you mind me asking where you got RCD cord as the old box type with behind power points Cheers Bruce. I miss motor writer like you John from wheels and long passrd Wayne cantell . I don't waste money on wheel or motor
I would suggest that every extension lead should be as a minimum 3 × 1.5mm2. Anything under should be banned , they are dangerous to use. Regarding Gpo's 10A. or 15A, apart from the earth , they are inside exactly identical. You can easily draw 15A from a 10A Gpo, on a single circuit of course.
One thing I would mention is that electric motors often found in air compressors have big initial power draw. It may be rated 10A and drawing as you said 9A during operation, but at startup, they could draw up to 7 times rated power. So not only you should refrain from running it via extension cord but if you do, do not plug anything else to it. Especially any electronic devices.
@@chriskennedy7534 It is true for induction motors even at no load. Just startup time is quicker but peak startup current remains the same on both load / no load cases.
@@Piasecznik72 I'll give you that, based on my limited oscilloscope experience, that's a wish list item. But compared to the multimeter owners group, only one of mine can delve that deep, including a couple of watt meters
Good advice to avoid extension cords. If you need one for a fractional hp motor like a Dremel grinder, make up a cord that is sized for the load and make the cord as short as possible. 2 or 3 meters is often enough. If wire size needed is in doubt, bigger is better. In the home workshop it helps to plan power needs against the power available. In my shop here in 'murica I run all 110/220v dual voltage motors wired to 220v to reduce the amperage draw. Think about what you have running at one time to avoid overloads. Watch the movie "Apollo 13" to see how this might be important.
Without having even started watching the video yet I thought I'd share my experience with extension leads and electrics cars. I plugged my Polestar 2 into a 10A outlet expecting it to charge at atleast 8A, it was charging at 8A initially but overnight that dropped to 4A and the car was nowhere near as charged as I was expecting by the morning.. it wasn't until grabbing the extension cord (with a big sticker saying made in china and 10A/2400W on it) that I noticed it was notably warm. As it turns out, most electric cars throttle their charging current based on the voltage drop of the incoming cable to stop them setting shit on fire, this is really useful when china are selling extension leads rated at 2400W with 0.6-0.8mm^2 wire in it.
Besides the gauge of the wire, the condition of the connectors matters, especially at high current draws. Oxidation on the metal surfaces of the connectors will significantly increase the contact resistance and cause heating of the connector and voltage drop (that Ohm's Law thing). You should have mentioned that another issue with the use of extension cords is the increase the number of inline connectors. I clean or replace the connectors on my power or extension cords whenever the metal no longer looks "shiny." If I have any question about a power receptacle, I just replace them. There are cheap and much less expensive than fires. The power cords an many things are in my view inadequate. I would just replace the wimpy cord on the longer one of thicker wire gauge installing a proper wall outlet was not an option.
just use a surfacing disc on the conductors, if you can. At least that is what I do on 50 amp 250 volt plugs for my heavy use tools, in the USA. Even common 15a 125v ends aren't exactly cheap now, but I agree that if they are bad, it is no good. My dad taught me as a kid that wire size mattered, so it has never been a problem, but most people don't know any better.
Hey John, spot on as always on the physics. I worked supply festival power through my 30’s and I’ve given this same explanation to so many mobile caterers over the years. In actuality a solid 2.5mm H07 rubber flex extension cable should be a standard issue in any fatcave, and using something like that would never be an issue, but I get your point on the warranty adherence. I’d like to see some more shade thrown at the manufacturers though who could easily use 1.5mm (or better, 2.5mm) for their cords and give people at least a few meters…. But then there is the issue of some Darwin Award contender coiling said long power cord! That would be a useful video as it goes! Let me know if you’d want some input on that video, could help avoid some house and fatcave fires! Great work as always sir!
Thanks very much, Darren. I agree. If 2.5mm^2 extension cords (and power cords from high duty cycle appliances) were the standard, most of this would go away. Coiled extension lead (in operation) = DIY induction furnace...
Fun fact: 2.5mm sq solid conductor has a lower current rating than 2.5mm sq flex cable. This is because the flex has more strands of finer wire to give that 2.5mm sq cross sectional area and therefore more surface area.
@@AutoExpertJC Not so much mate. The issue with the coil is the lack of airflow a bunched up cable has to get rid of heat. there's little in the way of inductance 'in the coil' - because the return runs right next to the live... so the generated fields largely cancel out long before they interact with anything around them. running the 'return' next to the 'live' is a common practice in AC circuits to minimise emitted fields. The coils in your induction stove for instance all 'turn' in the same direction, just like those in a motor winding. if they had 50% of the turns going the opposite way, then you'd get no flux in the motor tooth, and no induced current (thus, heat) in your pan (or wire) and therefore largely mitigated inductance in that air coil. you can do the test yourself if your willing... run 10A through 1 core of a coiled cable (use a dc power supply, for instance, no need for dangerous voltages, 5-10v will do plenty) and hold a magnet or bit of steel in the coil... you'll feel some of the electromagnetic force if you have enough turns coiled up. Now hook up the circuit such that it runs the same 10A back down the 'neutral' or 'earth' lines in the same 3core cable... you'll find far less (virtually none) of that force on the magnet/bit of iron. if you have an inductance meter, you can hook it up to the same 2 circuits, and see a dramatic difference in inductance.
@@sn0wchyld many extension leads have a helix. yes at domestic supply voltage the currents really arent high enough. but get a pair of high voltage wires evenly spaced and it can. swer systems have to have isolating transformers and bonding mats to control this inductance.
Any motor at risk of burning out from running too long is already poorly engineered. Not fitting a thermal cutout way, way worse. I've had a few paper shredders that that do that, keep feeding them for too long and you've got to wait a while for the motor to cool down. It's a reasonable compromise. You can of course buy more expensive paper shredders with a 100% duty cycle. Many of the cheap welding units are the same. It sounds to me like whoever made the air compressor being discussed is trying to circumvent Australian consumer protection laws and you seem to be taking their side. How can any consumer prove they didn't use an extension cord? Finally the voltage drop on a 20A circuit can be as much as the voltage drop of an extension cord using 1sqmm conductors. It's a function the resistivity of the conductor, cross sectional area of the conductor, r the current and the length of the conductor. Not all extension cords use all copper and not all motor windings use copper wire these days. The reasons to run air hoses rather than extension cords on building sites and factories is for safety and cost. Extension cords have to be tested and tagged. Air hoses and air plumbing I think gets a free pass. Not to say compressed air is 100% risk free.
Excellent advice for diys that just bought a compressor to play with. Also If I remember correctly start up current on most electric motors is significantly higher for a short period which is sure to heat up those 1.5mm conductors. On the subject of Albo I cant really imagine him warming up the compessor to spray the box trailer and although I dont always agree with his politics I believe his heart is in the right place!
Rule-of-thumb. Motor start is 7 times the rated current. That is an unloaded motor ( eg. compressor is completely empty ) Some will draw less, some draw even more.
I’ve always known it as 9 times the starting current, but not really important. We have a few 400 kW direct online motors at our plant and that’s enough to dim the lights. And they are baby drives.
@@michaelslee4336 And those direct online motors will pull even more that 9 times. ( I assume you mean the load as opposed to reduced voltage starters ) Main place I've seen full load DOL starting on "Large" motors is in power stations.
You made a comment about topping up car pressures occasionally. So, does this mean leaving air pressurised in the tank? I've been turning my compressor off and emptying the tank while cleaning up with a blowgun, then open the drain and leaving it open when not in use. Thoughts about leaving a compressed air tank full at pressure indefinitely ?
Don't forget, you throttle down your air with smaller air hoses just like smaller diameter electrical lines. So, while the coiled flex hose is handy it reduces the pressure you can supply to your air tool. Your couplers can also reduce the flow possible as well. So keep that line as big a diameter as you can as long as you can. First point you reduce the diameter you reduce the potential pressure everywhere past that point.
It's a bit like running fire hose. You may have to put 180 PSI in to get 150 PSI at the nozzle. The same concept applies to dust collectors in wood shops and even home heating and cooling systems.
Oh hell yes. I sell plasma cutters which require a certain flow rate (185 - 230l/min) at 90 - 95psi and so many customers run 20+mtr x 5mm air hose and wonder why their cuts are slow, the parts don't last and the plasma faults out. That's if they have bought a big enough compressor to start with. I have a customer that I sold a CNC plasma table to with a 105amp plasma cutter, he has now bought 2 home handy man compressors and it still won't work properly. I wonder why...
This is why I make my own extension leads, using 2.5 sq mm arctic cable.... then I PAT them to be sure... (Portable Appliance Test) 2.5 sq mm cable is good for 20A and less voltage drop
Hey John, I've had the same Finnish made air compressor for nearly 30 years. Its rarely done any real hard work but it has a cord not just short but barely 50cm. I've always run it with a 5m or less industrial style heavy duty lead with a minimum of 1.5mm conductor and never had an issue. Its been incredibly reliable and is a good friend. I get a bit of rust juice these days when I drain the tank after use as she's ageing, is there anything you'd recommend to put in the tank to help neutralise the rust?
who in the World measures Wire Dimeter with mm*2 Everything I have Ever Seen is AWG and it is your AMPERAGE and the Length of the Wire what will Determine What Size Wire AWG you need not Watts Not Voltage but Amperage it Don't matter What the Voltage is and Yes one horsepower is 750 Watts but that's with a Motor that is 100% efficiency and NO Motor is 100% efficiency so in the Real World we Say one horsepower Eletric Motor will Pull a Min of 1Kw or 1,000 Watts and can be More and Yes Volts Times Amps is Watts but for a One horsepower Running 110 Volts it will be a Min of 9.09 Amps if it is 120 Volts it will be a Min 8.333 Amps if it is 220Volts it will be a min of 4.545 Amps and if it is 240 Volts it will be a Min of 4.166 Amps. You can Run 75 Feet of 14 Gage or 14 AWG Solid Copper Wire know as 14AWG/3 and Run 15 Amp Breaker. if your Running 250 Feet and 15 Amp Breaker you'll need 10 Gage or 10 AWG Solid Copper Wires and I know I Say Wire but when I Say Wire I Really mean Wires and Yes you can Run only one Wire with AC and have Power is it the Right way to Wire up Things No but you can do it but you will need a Min of Two Wires with the Other one Going to Ground and to be to Code you Should have a Min of Three Wires one Black that is your Live/Hot/Power Line that is where your Electric Power is coming from one Wire being White this is your Common/ The Return to make a Closed Circuit and one Wire is Green this is your Grounding wire so if anything go's Wrong this will Flow the Electric to the Ground and Away from your Body. no matter what the Volts are Long as your not Running over 600 Volts For if your Running 600 Volts or More the only Difference you'll need to do is make sure the Wire is Rated for 600 Volts or More and has the Right Insulation on the Wire for that Higher Voltage other then that Normal Wire for Running Power Not Communications and there is a Formula for Length of Wire and Power Draw in Amps and Some of the Formulas have Voltage and Voltage Drop and heat Ect. but that is not so Important as what the Wire is made of and the Wire Dimeter/AWG or Gage and the Length of the Wire and how many Amps you'll be Drawing for the MAX Amperage you'll be Pulling at whatever YOU have Pugged in or Wired up and at Max Amperage you Shouldn't have a Voltage Drop of more then 3% to 5% So if it is 120 Volts you shouldn't have no less then 116.4 to 114 Volts when your Pulling Max Amperage and Yes Solid Copper Wire can Carry more Amperage then Stranded Wire but if your Moving the Wire around all the time like an Extension Cord you Should have Stranded for Solid Wire will Brake easier Moving and Bending around all the Time for if your moving it around all the Time and Bending it, it Should be Stranded Wire but Stranded Wire can't Carry as Must Amperage as Solid Core Wire and the Difference is not much but there is a Difference and it Can only be become Noticeable when you are Running High Amperage like the Max Amperage for the AWG and Length of the Wire for Long times So Soild Core to Stranded is not that Important Unless your Running that Zone or that Run of Wire at it's Max for Long Times without a Brake the Stranded Wire will get Warmer Sooner then the Solid Core Wire of the Same Dimeter or AWG/Wire Gage. and aluminum Wire of the Same AWG of Copper Wire no matter if it is Stranded or Solid Core Can't Carry as Much Power or Amperage as Copper Wire of the Same Dimeter/AWG and when your Talking about Long Runs and/or High Amperage it is Very Important you know What the Wire is Made of Copper, aluminum, Whatever but it Does Matter and it Matters Big So Don't Think an aluminum Wire of the Same AWG can Carry the Same Amperage/Power as if it was Copper for it Can NOT you'll need a Larger Wire Dimeter/AWG if the Wire is aluminum then if it was Copper Wire. and just Saying if you have Short Wire Runs Like 10 Feet and Less 10AWG Copper Wire can Carry 30 Amps Safely and the Shorter it is the More Amps it can Carry Safely like if you have a one foot Long 14 AWG Copper Wire you can Safely Pull 15 Amps not Stop 24/7/365 and Up to 30 Amps for 10 Second or Less Short Brust and if you have 10 foot or Shorter Length of 12 AWG Copper Wire you can Safely Pull 20 Amps 24/7/365 and up to 40 Amps for 10 seconds or Less Short Burst and Yes it can handle Longer Burst then 10 Seconds and not Burn up but it is not Safe to do so over the Longer Lengths and/or Higher Amperage just like for you can Safely Pull 50 Amps or even 100 Amps for 1 Second or Less on a one Foot Long 10 AWG Copper Wire but if you Take that Same 10 AWG Copper Wire and Pull 100 Amps for Minutes, Hours or Days or Seven Days you'll have not only a Hot Wire but you'll have a Melted Wire and Maybe even a Fire. Good Thumb of Rule for Wire Size to Amps your Pulling is for Every Even Number AWG you go up it Take Two Wires of the Next Step Down in AWG Even Sizes So Two 14 AWG is one 12 AWG, Two 12 AWG is one 10 AWG, Two 10 AWG is one 8 AWG, Two 8 AWG is one 6 AWG, Two 6 AWG is one 4 AWG and so on and So on and this Don't Mean with 14AWG/2 one White and one Black or 14AWG/3 one White, one Black and one Green is one 12AWG That is NOT What I am Saying for What I am Saying is if you have Two 14AWG/2 so you have Two Black and Two White 14 AWG or Two 14AWG/3 That would be Two Black, Two White and Two Green that would be = to one 12AWG/2 or 12AWG/3 that would Mean you have One Black and one White of 12 AWG or 12AWG/3 one Black, one White and one Green of 12AWG. Every Time you go up in AWG in Even Sizes it is Equal to Two of the AWG of the Size Below Keeping in Even Sizes and if you need Two Wires of 10 AWG Say White and Black or Black and Red and all you have is 12 AWG you'll need Four Wires Two White and Two Black or Two Red and Two Black. So Every Time you go up in AWG in Even Sizes it Double's in Dimeter but it don't mean that one White and One Black or one Red and one Black of 12AWG is Equal to 10AWG for it is NOT!!! you would have to have Four Wires Total Two Red and Two Black or Two White and Two Black of 12AWG to Equal Two Wire Total one White and One Black or one Red and one Black of 10AWG
yeeep, the piss poor copper clad alu (or worse iron!) chinesium wires commonly sold around the world today is a disaster. Discovered the hard way while building a high power UPS/Emergency power supply based on SLA batteries. The wires lost a ton of power = copper clad alu = twice the losses (and more!) than true copper wires. B'cuz losses, they also start to quickly heat up = increasing losses during use.
I have installed dump valves on all but one of my pneumatic outlets. It saves a lot of time not having to turn the outlet off then bleed the air out of the hose before disconnection from the outlet or the potential damage to a person's hearing. Love your videos. Also I'm 99% sure you can pull 10 amps max from each side of a double GPO unless limited up stream by a circuit protection device.
Generally that double GPO is feed by a 16 Amp CB ( or if rally old rated for a 13 amp fuse wire ) and usually that circuit has more that one outlet fitted. Most 15 amp outlets are also protected by a 16 amp CB but no other outlets on the circuit. The wire is rated at 20 amps if 20 meters or less from the CB. Long run, up the cable size. ( yes, 20 meters CB to GPO plus Ext lead( whatever length ) exceeds that rating ).
@@alanhilder1883 If there are other outlets on the circuit it just means the fuse or circuit breaker trips sooner if they (the other outlets) happen to be in use at the time.
Another great video John. My local hardware store sells 15A extension leads (1.5sqm) but with 10A plugs which gives another option to offset potential voltage drop without breaking the bank.
Great John , easy to follow for everyone.... well maybe except for Albo ! He's still struggling with his 27 pages ... oh I mean 1 A4 page sshh sorry Albo did I let the NO out of the bag 😂😂😂
Being a scientist I fully understand the physics from a classroom perspective. Thank you translating this to the real world. I often wondered why no extension cord and your explanation makes perfect sense. You are also funny in your delivery and makes it even more enjoyable!
The "bad" cord you shown 13:30 is not the worst, the market is flooded with 0.5 mm2 and 0.75 mm2 wire cords rated for 10Amps. I actually measured the wires in one, and they ware ~ 0.38 - 0.4 mm2 and rated of course for 10 Amps. Gone are the days of 1.5 mm2 wired cords rated for 15 Amps that everyone considered junk.
Lie in bed awake and get this into your head. Once you get Ohms Law worked out it will be a light bulb moment when it'll all make sense, so useful. ( maybe not in bed but with pen, paper and a calculator ! )
True, but straight Ohm"s Law is only truly accurate for Direct Current (DC). The Alternating Current (AC) motors on the compressor are inductive loads and therefore the power factor has to be taken into account. It will not introduce a significant error, but just saying for awareness.
When I was a novice carpenter I never grasped Ohms Law well enough to remember it until I found myself staring at the label on a 4 way adaptor & had an epiphany. 240 volts @ 10 amps = 2400 watts. Aha! So 240 watts is 1 amp! So, 120 watt thing @ 12 volts is 10 amps! That sort of set the meaning of the relationship of the values for me. Being able to calculate tool & component loads relative to supply quickly is vital when every day's set up is different. To this day I still picture that label on the 4 way for a fraction of a second.
Very well composed video for your specific power management regional standards. But this does not apply to many countries, since plugs can be very different, as well voltage and amp standards. This needs a quick summary, e.g. use at least 1.5 mm2 wiring for 2kw compressors, 2 mm2 wiring for 3kw compressors, etc... . Just like a good user manual, this needs to be simple-stupid because we are dealing with safety.
As a former Bunnings employee who worked in the toolshop and did the warrenty claims, buy the right compressor for the job. The Ozito oil free compressor is great, but not suitable for dusty environments and constant duty cycles. It's designed for pumping up tyres, balls and blowing the dust off the bench. Drain the water after every use and it'll last 20 years. If you plan on using thirsty rattle guns, working in a dusty woodwork shop or a daily driver with the air tools, get an oiled compressor with proper air filters. If you're not sure, rent one! Rent a couple, find the one which works for you.
I THINK possibly the other safety aspect is that an electrical extension cable can be damaged etc and be a extreme/fatal hazard whereas an extended air hose does not pose such a harmful threat (not saying NO threat…diminished threat) 🤔👍🇺🇦👍🇺🇦
A tip from another content provider who had tanks explode is never buy a compressor with a seam weld at the lowest point. Internal condensation will rust out the weld faster than sheet steel.
The greater problem is that the tank being made in a certain country to specifications totally inadequate and very very little safety margin, not that the seam is in the bottom of the tank.
I answered and said, "If I have found favor in thy sight, O Lord, show this also to thy servant: whether after death, as soon as every one of us yields up his soul, we shall be kept in rest until those times come when thou wilt renew the creation, or whether we shall be tormented at once?" 76 He answered me and said, "I will show you that also, but do not be associated with those who have shown scorn, nor number yourself among those who are tormented. 77 For you have a treasure of works laid up with the Most High; but it will not be shown to you until the last times. 78 Now, concerning death, the teaching is: When the decisive decree has gone forth from the Most High that a man shall die, as the spirit leaves the body to return again to him who gave it, first of all it adores the glory of the Most High. 79 And if it is one of those who have shown scorn and have not kept the way of the Most High, and who have despised his law, and who have hated those who fear the Most High -- 80 such spirits shall not enter into habitations, but shall immediately wander about in torments, ever grieving and sad, in seven ways. 81 The first way, because they have scorned the law of the Most High. 82 The second way, because they cannot now make a good repentance that they may live. 83 The third way, they shall see the reward laid up for those who have trusted the covenants of the Most High. 84 The fourth way, they shall consider the torment laid up for themselves in the last days. 85 The fifth way, they shall see how the habitations of the others are guarded by angels in profound quiet. 86 The sixth way, they shall see how some of them will pass over into torments. 87 The seventh way, which is worse than all the ways that have been mentioned, because they shall utterly waste away in confusion and be consumed with shame, and shall wither with fear at seeing the glory of the Most High before whom they sinned while they were alive, and before whom they are to be judged in the last times. 88 "Now this is the order of those who have kept the ways of the Most High, when they shall be separated from their mortal body. 89 During the time that they lived in it, they laboriously served the Most High, and withstood danger every hour, that they might keep the law of the Lawgiver perfectly. 90 Therefore this is the teaching concerning them: 91 First of all, they shall see with great joy the glory of him who receives them, for they shall have rest in seven orders. 92 The first order, because they have striven with great effort to overcome the evil thought which was formed with them, that it might not lead them astray from life into death. 93 The second order, because they see the perplexity in which the souls of the unrighteous wander, and the punishment that awaits them. 94 The third order, they see the witness which he who formed them bears concerning them, that while they were alive they kept the law which was given them in trust. 95 The fourth order, they understand the rest which they now enjoy, being gathered into their chambers and guarded by angels in profound quiet, and the glory which awaits them in the last days. 96 The fifth order, they rejoice that they have now escaped what is corruptible, and shall inherit what is to come; and besides they see the straits and toil from which they have been delivered, and the spacious liberty which they are to receive and enjoy in immortality. 97 The sixth order, when it is shown to them how their face is to shine like the sun, and how they are to be made like the light of the stars, being incorruptible from then on. 98 The seventh order, which is greater than all that have been mentioned, because they shall rejoice with boldness, and shall be confident without confusion, and shall be glad without fear, for they hasten to behold the face of him whom they served in life and from whom they are to receive their reward when glorified. 99 This is the order of the souls of the righteous, as henceforth is announced; and the aforesaid are the ways of torment which those who would not give heed shall suffer hereafter." 100 I answered and said, "Will time therefore be given to the souls, after they have been separated from the bodies, to see what you have described to me?" 101 He said to me, "They shall have freedom for seven days, so that during these seven days they may see the things of which you have been told, and afterwards they shall be gathered in their habitations." 102 I answered and said, "If I have found favor in thy sight, show further to me, thy servant, whether on the day of judgment the righteous will be able to intercede for the unrighteous or to entreat the Most High for them, 103 fathers for sons or sons for parents, brothers for brothers, relatives for their kinsmen, or friends for those who are most dear." 104 He answered me and said, "Since you have found favor in my sight, I will show you this also. The day of judgment is decisive and displays to all the seal of truth. Just as now a father does not send his son, or a son his father, or a master his servant, or a friend his dearest friend, to be ill or sleep or eat or be healed in his stead, 105 so no one shall ever pray for another on that day, neither shall any one lay a burden on another; for then every one shall bear his own righteousness and unrighteousness." 2 Esdras 2:31 ,,,''''
Also the plugs/GPO are a 'restriction' too... If you feel the cord on something drawing a lot of current, and then feel the plug, you will often find the plug is much warmer than the cord in general. Just something to be aware of, and use longer and fewer extensions as possible. Hopefully only one extension cord at most, and I would never use any more than two...
Awesome explanation as always JC. I have used a 20m, 15amp lead with 10amp plug daily as a chippy for 30yrs on a good old Aussie made Pilot belt driven air compressor with no dramas. (1650watt motor) I have it bolted inside a tool trailer, so it is a bit of a job to remove and is a two man job to pull out and carry to get close enough to a GPO. We find the belt driven type compressors start up a bit easier than the smaller direct drive units on cold frosty mornings when the air is cool and dense, but the downside is it always lives in the trailer.
Just don't coil up the excess lead somewhat neatly, that will cause massive problems. I was working near some boilies using one of those small, lightweight welders ( not the problem ). The boilermaker was complaining that the welder was playing up. I had a look. The welder was near enough to plug into the gpo ( powerpoint ) but they were using a ext lead, ( 15 a rated cable ) coiled up neatly. That lead was getting quite warm. Plugged the welder in without the ext lead, worked great.
And I’ve been using my belt driven 15amp plugged air compressor for 20 years on 10amp GPO’s with 10amp extension cords without one issue and it never gets remotely warm 😂. 🤫
Yes but the Pilot is a PROPER tool with a motor with a proper starter capacitor circuit etc....The compressors Mr Cadogan is reviewing are not well designed and have great internal inefficiencies.
@@Warpedsmac ooh this makes absolute sense to why I’ve always had zero issues skirting around technicalities because I generally always buy the best quality tools I can. Sometimes you just forget how much average, cheaper quality stuff there is out there on the market that cannot be compromised.
@@NatesToolbox Yep, we use various direct drives as well and like you run fine on extension leads, except some brands won’t start up on cold frosty mornings, but then they are light enough to pickup and plug into the meter box and all good.
Yeah you would want to use a heavier cord rated for the amperage draw of the device you're using at least something a little higher to give you a cushion so you're not endangering the plugs cuz the plugs also will be your main failure cuz I've seen it before we're yet the device said it can handle 15 amp draw but I seen the plug slowly change color on the wiring in the coating that was on the plug going from Gray to a brown and becoming extremely hard and it was only carrying just the maximum limit! On that extension cord so I always recommend to have a cord that can go higher amperage than what you're really needing so you're not blowing up your plugs
Install a 15 amp outlet (socket, GPO? whatever) (IPxx weatherpoof) on the wall with a dedicated 2.5mm2 cable on it's own breaker (DIY of course because why not) and plug in whatever you want with a 1.5mm2 extension with 15 amp plug and socket (DIY again) and everything's good. Hell while you're at it charge your EV at 13 Amps, but wait, there's more. Hardwire another 13 Amp EVSE brick and charge 2 EVs at the same time. Just make sure you actually know what TF you're doing and make sure the cable has plenty of free air around it and limit the total current to 25 Amps which is what 2.5mm2 will handle.
I'm slowly building up to a decent work shed. I bought a fixer-upper house and over the past 3 years i've found it's better to do the work myself, hence the tools getting purchased. This has extended into doing my own mechanical work with my car and motorcycle. I just bought a torque wrench last year, and my next purchase is going to be an air compressor. So, perfect timing in the last two videos from you. Thank you.
I did the same here. i don't like to hire people to do the jobs that I can easily do. Especially these days, these "professionals" are really ripping people off with jacking up the prices to stupid numbers. Eg. I got a company to quote me on replacing the sewer pipes in the basement. The ridiculous quote was about $19,000 dollars!!!!! I bought the materials that I needed, INCLUDING a jack hammer and piping. I did the entire job in 3 days (yes, I'm slower than they are) and my total cost, INCLUDING the jack hammer, was about $400 ish dollars!!! My attitude is that if someone else can learn to do something, so can I. It's worked out well. As for the compressor, however, at some point, I want to replace mine. Not that it's not working right or anything like that, but that it's old now and I have to assume that the tank is rusty on the inside. When that happens, these tanks can explode and take out a wall or kill a person if close by. I've seen videos on that. So the next air compressor I buy will have an Aluminum tank!! No rust to worry about. As for my tank, I've been lazy, because to confirm what it's like inside, I just have to remove an end cap and stick the borescope into it and have a good look to confirm if it is in fact rusty or now. It's fun to do things ourselves and save $$$.
@@BlondieSL Old air compressors are some of the best. Mine is at least 30+ years old and the other one is a 1947 model. I rebuilt the 1947 model pump and bought a new steel tank, without epoxy lining. Epoxy can help the rust. My auto drains are tied to the pressure switches. The tanks drain the water every time the pump cycles and only when it actually runs, so I never have to think about it. The newer one has a rusty tank. Explosions are rare and usually they just leak, but I have considered replacing the other tank. Check out the Garage Journal Forum, if you haven't already. It is for guys like us that DIY, are pros, and do mechanical stuff. I am a pro in multiple trades so stuff like the electrical talk is old news, but it is all true and relevant and garage journal has been a great resource to learn more, especially about equipment. There is so much information on air compressors, bench vices, and anything else you can think of, from people from all over the world. Cheers!
@@CGT80 Thank you! I will check out the Garage Journal. The site looks interesting! As for my compressor, as soon as I can get mobile again, I'll check it out inside and if it's not rusted out, I'll keep using it. But I'm contemplating preparing 2 or 3 old 20 lb propane tanks to add to its capacity. But I need to add these tanks with a quick release option so that I can move the main compressor in and out of its location for oil change and such.
I've got a problem with your comment that "the motor current must increase as the voltage dropped". Youre using the P=IxE formula in a way assuming P is fixed. Its not. You must factor in thats its no longer a 2Kw motor when supply voltage drops. The 2Kw is a name plate rating only assuming supply of nominated nameplate voltage. I think if there is rise in current it would be due the drop of rpm as the rotor and stator are getting out of sync due to the loss power supply. Another factor to consider is starting current. Usually about 4 times FLC. Getting the started thru the 1mm ext cord is a big issue. When your 5 amp motor sucks 20 Amps at kick off. Your explanation of house wiring and ext cords is top notch. Dont forget HPM has 2.5mm ext cords as well.
If you are going to make assertions, as you have. You better get your facts correct next time. Start Current on a standard Induction motor, (single phase) with capacitor start, is closer to 7 x FLC. P is determined by demand, P does not decrease as voltage drops, A increases as V drops, this is why leads cook and motors trip overloads, whether they be manual restable or auto resetting thermal overloads. Again, P is determined by demand, especially for a positive displacement pump, which is what a compressor is.
It gets even worse in the US, where the standard wall outlet is 120V 15A. That's theoretically 2.4 hp, but practically you can really only run up to 1.5hp motors. 240V is available, but most houses just have couple of outlets for a stove and a clothes dryer, so if you want to run a 240V compressor, you'r probably going to have to install an outlet for it or hard wire it. The good news is that extension cords of up to 12AWG (4mm^2) are readily available. Of course you need that thick, expensive wire if you're running significant power at 120V
Hi John, On a slightly related note I'd be interested in a video regarding air compressor vs battery tools for DIY mechanic use, particularly an impact wrench. The pros/cons, costs etc. Greetings from the UK.
Air tools are nowadays cheap, reliable* (if maintained), scalable for agricultural or construction use and multi use. Batteries are portable, plug and play, no leads, quieter and low maintenance. Batteries are more suited for home duty and trade with passenger cars, Pneumatic still has advantages for Mining and Agricultural machines that require more oomph.
Battery 1000% better, air is more powerful at the high end but I've never come across something my Dewalt mid torque can't undo and if I ever do they make a high torque that is significantly more powerful again. So much more convenient, quieter, easier, Price really is up to you, the cheapest battery stuff will be cheaper than the cheapest air system but both can be very expensive if you want quality. Air tools are pretty much a lifetime tool, battery not so much but they do last a good while especially for a home gamer. I chose Dewalt because Bunnings sells it and is both close and open late, it's also cheaper and close to as good as Milwaukee which would be the money no object choice. Other people have lots of luck with Ryobi though and it is definitely the bang for buck choice
@@aslkdfjhg Air power has its niche in things like some industries, agriculture and mining because they work with so much stuff that can blow up given enough sparks and fire. Coal, grain dust, gasses and various vapours all can contribute to a local extinction event for the region. For the average mechanic you're probably better off with electrical for the most part for ease of use as compressors do need some kind of maintenance cycles of oil and cleaning out the cylinder sometimes. Course if you're doing very heavy work on site based machinery or large vehicles all day, air can come in handy for heavy lift jacks and stuff too. Or if you end up being the lucky prick changing about a billion lug nuts on a truck or something
There are some things that pneumatic is the only option, battery stuff is very convenient for reducing noise and not walking around tethered. I use both, I perform many different tasks.
I get that you tried to keep the story short but a big issue with all single phase capacitor start motors is the high starting current that is drawn momentarily on switch on, typically 5-7 times the full load current stated on the name plate of the motor. Any excess volt drop while starting extends the time taken for the motor to reach operating speed and stresses the motor starting winding and the starting capacitor both of which have short time ratings. (If the starting time takes too long your circuit breaker will trip and the compressor won't be able to run.) These short time ratings for the motor starting components are why single phase motors are specified with a maximum number of starts per hour. If using a single phase compressor with high air consumption tools you need a compressor with a continuous run operating mode otherwise your motor will eventually die if it is repeatedly cycled on and off by the pressure switch. My solution was to make my own extension lead out of 2.5 mm sq. flex so the rate of volt drop in the lead is the same as the rate of volt drop in the wiring in the wall.
I think that's the ideal solution. I appreciate the tips about the surge on start - explains why I've never been that successful running a compressor with a battery-inverter system.
@@AutoExpertJC The same situation exists meeting starting current requirements with electric motors supplied from a small generator. Power tools with built in electronic speed control or soft start are usually no problem but any machinery with single phase induction motors running from a generator need the generator output rating to be several times higher than the motor name plate rating for trouble free starting without undue stress to either the motor or the generator.
Wondering if you did do the multiple cable trick that you mentioned, putting a watt/power meter directly on the GPO, and then a second time putting the meter after your 15a cable and measure the actual 2 voltages. If you're still getting 215-220 out, it should be fine. If you're getting 190-200 on the power meter, then you know the voltage drop is likely to cause damage.
That was a great video. Living on a houseboat and seeing what some people do for power is quite scary. We have a 15A pole and plenty of boats run a piddly little lead. Same with the lead from generators. People need to realise that extension leads have a lifespan and replace them as required. Also if you suspect power points have been installed unlicensed, get a sparky in to test it all. Still can't beat that Highway Patrol Tesla charging lead though.
You have touched a very interesting point: GPO with a 10amp rating protected by a 20A circuit breaker! A sure recipe for a fire death! As mechanical engineer i have had stand-up fights with my electrical counterparts and I thiink regulations must be updated!
My dad made up an “extension cord” out of what looked like 4awg (coulda been 5, but close enough) stranded, so you could actually coil it. It was heavy, made of “ found” wire, but nothing got hot and nothing ever died, including humans. It was a bear to haul its 50 ft length. But it was safe. He was among other things, well versed in electricity and passed along the wisdom.
As a sparky, I say this is all good advice, and yeah I wouldn't be concerned with using an extension cord on the odd occasion, especially on a small air compressor such as this. If you really do need more length in a permanent position, just get a sparky to replace the pissy flex lead with a heavier 2.5mm2 flex lead.
Great video John small point about cross section increasing flow of Amp or fluid being related to R^2 . The Radius Squared has a huge effect on the flow so a 1 square is not half a 2 square cable.
@AutoExpertJC there are 2 other reasons to be cautious, one more subtle than the other. 1/ People often use extension leads partly on a spool, which causes overheating of the cable on the spool, more resistance and more voltage problems for the compressor. 2/ a coiled cable has inductance, especially if there is iron close to it, and that causes a voktage drop with phase shift (minor I will admit) and the compressor sees lower effective voltage and higher current again, to achieve the same power. Or, in the worst cases, all these things add up and the compressor fails to start, making a buzzing sound until it rapidly overheats. Only seen this once, but the smell was 'orrible!
I don't buy the "inductance" point. The currents in the conductors (live and neutral) are balanced, and unless you've taken extraordinary care managing the twisting of the cable, the orientation of the conductors with respect to each other in adjacent turns will be random, leaving the coil with close to zero inductance. (Close to, not exactly zero, because it will still have at least the inductance of essentially a shorted transmission line.)
Speaking of compressed air, in the dream time I was the Maintenance Manager of a drilling company during the "arms race" of ever higher air pressure for precussion drilling, at the start of 1990 900cfm @350 psi was "big air", at the end of the 90's, it was 2 x 1350cfm compressors feeding into a booster that increased the pressure to 1000 psi. It was like the Apollo program, a lot of failures along the way but now the norm and exponentionally increased the penetration rates and the depths of compressed air drilling, 1990, 120m depth, 1999, 450m depth. That being said a lot of diesel getting burnt to drive all of that, 2500-3000 litres a shift, we wouldn't have got a Christmas card from Greta.
Wow! That is some big stuff. I have a "little" 5hp 17.3 cfm at 175 psi westinghouse air brake company compressor. It is small for the series that went to 25hp or so, but with a motor at 109 pounds and a pump easily the size of a motorcycle engine, it is big compared to many home shops. My uncle had the 25hp version for the blast cabinet at their abrasive blasting shop but they ran 125 to 250 cfm diesel units for blasting rotors and parts for power plants in the western USA and Hawaii. I have only seen 1,000 cfm units on trucks in SoCal but haven't seen what they are used for or anything bigger. That is cool stuff and would have been fun to learn about.
Fun fact: if you're hose is super long (no pun intended) and your application needs large volumes of air you'll experience a pressure drop through the length of the hose too. Either way you're screwed 😅. Great video and explanation, although I know how it works I could never explain like you do.
I would think inductive effects would be very minor, as current is flowing in opposite directions in the two conductors, so magnetic fields should mostly cancel out. But having all that wire coiled together with no room for air to circulate around it is definitely going to make it get hotter.
Great video, very well explained. Given the compressor theme, how about a video on the different types of fat cave compressors, pro cons, including the sweet spot for decibel output. Some are horrendously loud.
So the five white 5m extension cords I have joined together, off the double adapter, that also has a double adaptor into the $9.99 power board (such a great buy), that’s attached to the other power board dad used in the shed when I was little, that still worked good after the flood of ‘83, that’s plugged into that power point I put in, running off the old light bayonet in the shed roof that dangles a bit, but it’s ok because it goes back to the fuse box where I swapped out the 10amp fuse with a bit of old coat hanger wire and that’s all powered the compressor fine, except that time there was a small fire, but then I was able to repair the insulation with some duct tape that was left behind by a tradie, oh shit I forgot to take a breath! …Boom!
Done that. Also dismantled old triangle shaped double adapters and modified the earth slot(s) with a hacksaw blade to accept the 15A plug - no expletive ridden argument with getting heavy cord into 10A plugs.😂
FWIW, I live in the U.S.A. Many years ago I bought a 120v MIG welder. I needed an extension cord for it so I added the matching 15A male and female ends to a 50A R.V. extension cord. Yes, if you tin the wires you can fit them correctly into the terminals without fraying. I also use this cord for a more recently gifted 120v air compressor. In the last 15 years of use I have never had an issue with either the welder or the air compressor.
This is a problem with the kind of compressors available at what Americans call a "box store". Supercheap Auto WallMArt, Costco, Bunnings, Repco, Mitre 10, Aldi, Big W, etc even Sydney Tools sell some cheap ones . This problem does not occur with a decent compressor...AND this problem IS NOT LIMITED TO CHEAP COMPRESSORS.
I'm a retired electrician I think the warranty "assumes" that any extension lead is going to be no more than 1.5mm There would be no difference electrically between having a 2.5mm fixed wiring run out to your garage with an outlet on the wall, and a 2.5mm extension lead, just make sure the extension lead isn't coiled while in use Keep extensions as short as possible, it's best to have several shorter ones that you can daisy chain if you need them longer. My answer if i couldn't install fixed wiring would be to use a 2.5mm extension, but tell the service dept that it was plugged in to a fixed socket, i'd like to see them prove otherwise. I regularly made extension leads with 2.5mm cable, mainly for steam power washers around the farm buildings. btw, there will ALWAYS be volt drop, but the thicker cable reduces how much, put a voltmeter on your socket and compare when the compressor is on or off
Never ever buy pissy extension cords. All my cables in and outside the wall is minimum 2.5 m2. 1.5 mm2 is rubbish in my opinion. The difference in price is minimal. In Switzerland we have 230 V 13 or 16 A.
Yep. I years ago replaced the primary cord on my (long past warranty) Craftsman 5 gallon compressor with 20 fee of 10/2 AWG Romex going to a 20amp wall outlet. Plenty of current room as well as enough cord to go anywhere in the garage..
Damn!!!!.........I bought a new shop compressor a year ago and had forgotten about the "No Extension Cord Warning"......thanks for the reminder.........
When I was living in Perth a few decades ago a stupidton had a problem with a fuse always blowing. His solution was to twist a 3 inch nail into the fuse spot. The fire brigade found the 3 inch nail in his power box when they investigated the cause of the fire which burnt his house down.
I would say that having the option to plug in a 15amp cord into a 20amp outlet is also just as wrong as the other way around since you can actually overload the cord with too much current, The standard we have here is always that the total circuit fuse can´t go above the weakest rated wires in that same circuit, we normally have more fuses in the main fuse box instead and they will pop before any outlet can be overloaded no matter what kind of extension or load we connect. we have but one kind of power plug for 230V and our standard 3-phase for bigger stuff.
Thanks John for all the useful comments, which I'm sure most people will find eye opening and helpful. I hope you don't mind but, I wanted to add a few comments to supplement your info. I am in the US where the mains/line voltage is 120 and 240 volts. Most low cost compressors 1.5 hp and less use 120 volts. Most of these compressors use a single phase induction motor, which has poor starting ability and is very touchy about input voltage. Rated induction motor input voltage in Australia is 210 to 250 volts but, the motor runs cooler if run towards the higher end of the range; like 240 volts. Starting surge current is about 10 times the run current so, I would highly recommend an extension cord with 2.5 mm2 wire. If the manufacturers of compressors made for jobsites really knew what they were doing, they would use a brush motor, which has has no problems running on lower voltage (except output power naturally drops). Duty cycle on these low cost compressors is about 20% so, between using an undersized extension cord and running the compressor in full sun on a hot summer day, stands a good chance of over heating the compressor if you are constantly emptying the pressure tank. Motor efficiencies can be quite poor on low cost compressors. I have seen efficiencies as low as 30% with a 0.55 power factor. Although, most efficiencies run 50 to 70% with 0.6 to 0.95 power factor. And to conclude, I guess one of the best kept secrets related to compressors is the air delivery ratings: which measures the compressor suction airflow rate, not the output flow rate as one would automatically assume.
I have a question for all you experts. I have a shed/workshop 30m from my house, Power is from an insulated outside 2.5mm cable. I don't worry about overloading the supply, my reasoning is that I only use one tool at a time. Plus The radio. Wrong or right, This has served me well for many years and I'm not looking to change it. Question is how would I fit a smallish compressor to a setup like this? U.K 240v supply. Thanks.
This advice also goes for your welders, especially, if you can't seem to spray electrons and molten BB's in any decent manner. Voltage drop at high electrical loads could be the culprit, or you just suck at welding. 🤣
Heheheh. As YOU SAY @ 22:28.. Just buy/make a fkn long airline! Geezuz!! Its air science! Not rocket surgery! I’m a long time stalker… Love yer work Mr. C..
What is the AWG of the power cord? Voltage Drop is affected by length of conductor. I prefer 12/3 extension cords to accommodate multiple loads. A 4 outlet box with a GFC helps. One of my extra jobs in the Navy was inspecting electrical items in my squadron, personal and tools, and either certifying or confiscating them. Wires get stretched and insulation wears out, so simple tests and inspections improve safety and performance.
At tech we got told about the water in a garden hose analogy. The water in the hose is the current and the speed at which the water travels is the voltage. Crimp the hose at any point and this will create a resistance and slow the water down, this is just like a voltage drop.
Plug into the garage 120VAC 20-amp outlet and charge the tank. Roll outo the vehicle and fill the tire. Have used thextension cord many times. No problems.
By using an extension cord, all that you are doing is installing a resistance in series with the impedance of the motor. This won't hurt the motor in the least, but if the conductors (wires) in extension cord aren't of sufficient cross sectional area, they will overheat and possibly cause the extension cord insulation to melt and burn thereby igniting your home and leaving you destitute. As for the compressor, it is simply receiving a bit less power from the circuit breaker because some of the power flowing through it is being used to heat up the extension cord. So, get a beefy extension cord and you'll have no problem. In the US, we typically have 16 AWG, 14 AWG, and 12 AWG extension cords available. AWG stands for American Wire Gauge and the smaller the number, the larger the cross section of the wire. 16 AWG conductors are 1.31 mm^2, 14 AWG conductors are 2.08 mm^2, and 12 AWG conductors are 3.31 mm^2. Basically, for every decrease of 3 AWG numbers, the cross sectional area doubles (but you rarely see wires produced in odd gauge numbers). You might note that these extension cords seem large by Aussie standards, but that is because our standard residential power is at 115 VAC rather than the 230 VAC used in Aus., so we need double the current to deliver the same power at half the voltage as you all use. In any case, I've used extension cords to power a small home compressor many times on many projects and never had any problems, but my extension cord which should have been a smaller gauge did get fairly warm to the touch. Since I was always working outdoors with the extension cord laying on concrete, it wasn't really a safety concern to me.
Spot on, thanks for the valuable video. I sat down with pencil paper and calculator to determine the compressor needed and 2 hp would work safely. A friend of my complained that the 5hp compressor would not work. I tried to explain to him all of this . In America normal find 120V and 15amp circuit. Best Regards!
Yep, sounds about right, only thing I would add is that it's generally the startup current of the PEM motor where you come unstuck, as the small gauge wire can't deliver the large inrush current the motor needs to gets started and that's how the windings in the motor get burn out.
Thanks. Love this video John. 1976 I think it was I got a call. "The refrigerator you sent us is not working and our beer is not getting cold". Ho hum it was working fine when we pre trip tested it yesterday. So off I go and low and behold there's our perfectly good refrigerator with a 30 metre lead connected to it still wound up on the ground with the sun shining directly on it. Lots of other stories like this especially to keep the beer cold in my army days as an electrician. Enjoy your videos but a little hesitant to leave comments as my grammer is not that crash hot. Russell.
Thank you very much, Rusty. Apart from it being 'grammar' I think you did very well. 9/10 mate. I get what you're saying about the war stories from the great unwashed...
... and "lo and behold"! I didn't notice any problems with your grammar. Punctuation is great, 99% of spelling is good, great capitalisation, even have paragraphs. What's not to like? You did a better job than most of the commenters I see. More than 9/10 from me.
I replaced the short cable from my portable Makita, and rewired it with 7 meters of 12 AWG which can easily handle 25amps. Compressor motor doesn't heat up anymore than it did with the short cable.
Few things to mention... Firstly, pretty much everything you said was correct. The only exception was the typical failure mode. An under voltage failure on a single phase motor will typically be the capacitor failing rather than the windings. The start cap has a rated duty cycle, when you under volt the motor the motor won't have the rated torque, which when presented to the load will cause it to run at a slower speed. In the instance when the motor still starts, it will generally take longer to do so, heating the cap up more than it was designed for and limiting its lifespan. If you really under volt it, it wont spin over fast enough to trip the centrifugal switch, leaving the start cap connected until the breaker or thermal cutout trip, or the cap blows up. The windings absolutely heat up as you said, but the cap will generally go first. Most modern houses will run 16A breakers rather than 20. In either case though, the breaker doesnt trip at its rated current straight away. They have a curve. A little over, at say 20-25A, its rating could see it last hours before tripping. Not a lawyer, I'm an electrician, however I believe it's the case that you can do electrical work on appliances etc that plug in. So DIY cable replacement and extension cords etc are ok. Not saying theyre a good idea, just that I believe you're allowed to do it. Don't take my word for it, check for yourself first. The actual current drawn isnt as simple as converting hp to current either. For a 2.5hp compressor drawing 8A thats a marketing ploy. Yeah, its using 2.5hp worth of electricity, but its only doing 1hp worth of useful work, at most. That asside, when starting the motor current is substantially higher. That 8A motor might be drawing 16A or more for that period. The voltage drop is based on that inrush current, not the 8A. As for what to do about it, I'd suggest that the best solution is to go down to Bunnings (or whatever) and buy 2.5mm² 3 core orange circ and a couple of plugs and have your sparky do you up an extension cable. Unless your switchboard is quite a long way away, you wont have any issues with voltage drop and I'd suggest the warranty department wouldn't be able to tell.
Yes to this. In NSW at least , an electrician is licenced to work on/install ELECTRICAL INSTALLATIONS, An electrical installation stops at the GPO.light switches and sockets. The Gas and electricity act 2017 in NSW specifically states that devices that are plugged into a GPO are not part of an electrical installation. Think about the appliance repair man , or warranty work on your plug in gadgets. They are probably not being repaired by a licenced electrician ,but an electrical engineer or technician.If you dont feel confident in what you are doing re electrical repairs ,find someone who is. MAKE DOUBLE SURE THE THING YOU ARE WORKING ON IS NOT ENERGISED. discharge capacitors that are in circuit, they can hold charge for a long time.
When I wired my Garage [and got my sparky mate to check it and effect the connection to the bit I know not to touch] I put some old fashioned ceramic fuse wire [old federal fuse] types in the circuits as a tool safety as waiting for a breaker on the board to throw on an amp overload might damage a shorted out tool, paid off one day when I jammed a table saw and expected smoke from the motor following the terrifying growl signalling disaster. the low amp fuse blew and saved the day.
Once you add 3 lengths of air hose, you can then jack the pressure cut off switch to 8 bar ( under the black plastic cover ) Then who gives a cr4p about power cords.
Really appreciate the explaining of relationship between voltage - amperage - horsepower. I have a 240v 6hp beast, and I parked it 5 feet from my breaker panel in the garage and ran the dedicated 240v 20a outlet so I can use the factory lead, which by the way, seems fairly thick and robust. The one aspect you didn't mention is volume and pressure drop if you use gimpy air hose over long distances. I have 3 20 foot hoses, and I only use as much as I need to reach where the work is. The other option is to run pipe and have outlets along the way so you can have full air delivery a fair distance from your compressor. As you said, an air nailer doesn't put much demand on air delivery, but if you are polishing a car with a polisher that eats 11SCFM at 75PSI you are definitely not going to want to have 15 or 20 feet on unneeded hose coiled about on the ground starving your tool of air. Great video, and I am not one of those who wishes to prove you wrong (like you said) - because you certainly are not - but just wanted to add that aspect. Thanks for another great lesson.
Thanks John as a sparky in a former life, still registered, I can say you pretty much nailed it for the lay person! I had my mental list and you managed to address the lot. Even the duty cycle issue. well done!
Thank you very much. Coming from you, that means a lot.
First thing I did was redo all the electrical on my boat, aadd solar and batteries, and bring it up to current specs. We have to get a certificate for gas, elecrical and a seaworthy survey every five years for insurance purposes. That's an out of the water inspection too. I hate to think og how many homes haven't been looked at or have had DIY additions without seeing a licenced sparky.
@@grantleyhughes - hoe many extension cords with no tags -uggghh.. or custom replaced ends, shudder (actually the ones with bare single insulation on pulled ends much more worrying (that old cloth insulation, all frayed - lol...
I bought a reel of immersion heater flexible cable (2.5mm) to make an extension cable. Works perfectly.
@@Choober65 I'm really hoping this is irony or sarcasm.
John, you may also consider doing a video on the maintenance of home compressors or lack there of. Plenty of DIY'ers fail to remove the moisture from the tank after use and after a few years the rust in the tank can cause a huge explosion similar to a bomb going off. take a look ruclips.net/video/sm_FJ6Pat4I/видео.html
Not sure what the "explosion" is all about, but yeah, moisture left in the tank will eventually show up under the tank as pinhole leaks.
@@TheReal1953 You should google "compressor explosion". Once the rust has compromised the tank, the pressure will build up in the tank and then the tank lets go.
@@EricBanner571 I would think that's a function of a humid environ and poor maintenance. In all the yrs around compressors and dumb people, I've never seen this occur. What I DO see is tanks starting to leak at the bottom because of trapped moisture.
Wow. Um, don't most compressors come with a manual that explain this? Or am I one of the few 'wasting time' reading manuals?
@@VinceA-jq6ds About the "explosion" potential or draining the moisture from the tank?
Thanks John, I never learnt this stuff my dad works in an office 😂. Love all the practical advice style videos
Glad to be of assistance mate.
I worked in an office and I don’t understand what PowerPoints have got to do with this video.
I haven’t seen a single presentation in the video. 😜
@@Conservator. Just go talk to your WHS officer, I'm sure they've got multiple PowerPoints relating to electrical appliances and not using extension leads with them. I know ours does.
John is spot on again my dad was a electrical engineer and I've worked in electrical wholesale and as a kitchen/furniture maker, I have 3phase connection to my house so its great for welders, compressors and aircon but do do tend to use smaller 10a welders and compressors more often than my bigger older ones and nearly all my power tools that my dad passed on to me have upgraded cords along with a few of them amphibian type 15a to 10a cords with a rcd or breaker in them that were home made long before you could buy them amphibian leads
Great video John. The air compressor situation also explains problems you get with extension cords in general. Like why does my power tool lack power using 100m of extension cord ? 😀
Using a voltage drop calculator and some research, I got the voltage drops for various extension cords. This might help people get an idea of which cable and length to use.
For the 2.75 hp compressor, 230 VAC at the plug, and a power factor (think efficiency) of 0.95, there will be 9.39 A current draw.
For every 10m length of -
Standard 10A extension cords, 1mm² = 4.84 VAC drop
Extra Heavy Duty 10A* and Standard 15A extension cords, 1.5mm² = 3.10 VAC drop
Extra Heavy Duty 15A and 10A^ extension cords, 2.5mm² = 1.69 VAC drop
Remember these numbers are at nearly full capacity (10A) of the power socket, if you are using less current then the voltage drops will be proportionally less. Half the current (5A) = half the voltage drop.
* Not all Extra Heavy Duty 10A extension cords have 1.5mm² cable. Always check.
^ Only found Delta brand had 15A and 10A, 2.5mm² extension cables. There may be others.
Calculator I used - www.jcalc.net/voltage-drop-calculator-as3008
How much voltage drop can you have? The allowed voltage at the power socket in Australia is 216 VAC to 253 VAC. If you get the average 230 VAC at the socket then you shouldn't have more than 10 VAC drop, giving you 220 VAC at the end of the extension cord.
So for close to 10A draw from the power socket with 230VAC or more -
Standard 10A extension cords, 1mm² = max 20m extensions
Extra Heavy Duty 10A* and Standard 15A extension cords, 1.5mm² = max 30m extensions
Extra Heavy Duty 15A and 10A^ extension cords, 2.5mm² = max 50m extensions
Again if you are drawing less current you can use a longer extension. Standard 10A extension at 5A = max 40m extension.
One last thing is you may need to factor in the distance of the power socket from the meter box. That length of wire will also have a (smaller) voltage drop that will affect the total and your extension cable length.
Hope this helps as guide.
The allowed voltage drop in the run from the meter box to the socket outlet is already subsumed in what you quote as the allowable voltage range at the socket outlet - 216-253V. It certainly is in my country, which I expect substantially borrows from the same IEC standards as yours. So as a user of an electrical installation, you shouldn't have to worry about that. (But your electrician who installed it, should have.)
@@bpj1805 yes for fixed wiring it has been calculated. BUT for extension leads it has not. our nominal voltage range is 220 to 250 volts. most will read around 238v rms at the outlet under no load conditions
The thing that both you and John overlooked is that electric induction motors draw 3 to 5 times their rated running current when they are starting which drops the voltage even more. Granted, this is only for a very short period of time, but it does need to be considered.
@@BryanTorok True. Looking at the instructions for the Stanley Twin Stack Air Compressor , the compressor has a rating of 2100W, around 9.5 Amps. It also states Minimum Generator Size of 5000W. From this I would surmise that the peak (startup) current could not be much more than double. Otherwise the generator would stop/stall or a mains breaker would trip. There may be a soft start circuit on the motors to reduce the startup current.
@@tonyonofrio1147 Typical (not inverter) generators have a peak (short term) rating of 20% to 25% more than the constant running current in part to allow for motor start up current. Inverter generators are not that generous.
As an electrical engineer in the uk all I can say is fantastic communication on a subject that is not well understood.
But isn't it so much easier in the UK?
Our power points are all the same, there's no thick and thin earth pins to worry about. Ring fused at 32amps radial fused at 16-20 amps.
3hp motor would be hard wired into the mains circuit.
The only real problem, yet again, are humans who tend to plug anything in at any time, without looking at the fuse in the plug. The amount of power cords going to computers, table lights, battery chargers, etc, fitted with a 13amp fuse is frightening!!
We don't have shitty extension cables like that in the UK. Our plugs, sockets and extensions are all rated at 13A. A half decent welder gets pretty near to that limit in the UK so I don't know what they do down under. I put 16A commando sockets in my garage for this stuff.
@@PJ-om2wq My _WHOLE_ workshop runs off an extension lead from the house - can't get a reliable electrician to even keep an appointment round here - gave up!
I run welder/compressor and lights simultaneously through a cheap surge protection switch block - never tripped out.
You are spot on, every point, and a well explained video for the layperson. Sadly induction motors are very sensitive to voltage drop and this advice carries equally through to things like brick saws etc. Universal motors like grinders and drills are immune to drop, other than a reduction in speed and torque of course.
In the real world, these compressors work quite happily on reasonable lengths of extension cable as long as they are at least 1.5mm and as you rightly point out, its just a 400 dollar investment, not exactly world shattering.
In my own fat cave, there is a 5HP unit running from a dedicated outlet on a sub panel but I do also own a cheap 2.5HP unit and its been known to run at the end of 25 meters of half decent extension cable without any problems what so ever. The big compressor is for shop air and heavy use, the little compressor is for portable use around the farm, haven't killed a motor yet but have had many mechanical failures on the cheap units. Just my 2 cents worth, others mileage may vary.
Thank you, Sir, that was as good as it gets for a master class on electricity and compressors. I'm here in New York City, USA and truly enjoyed your teaching style and depth of knowledge. Awesome!
Its always fun for the whole family when physics gets in the way of convenience
Yeah. The facts - so pesky.
The longer hose also gives more air capacity effectively increasing your tank volume.
@@davidrice7740 Very cool unintended bonus.
But you will get pressure drop at the device with cheap longer hoses & connections @davidrice7740
I find you very entertaining, John. As an American, it's refreshing to hear your Aussie idioms and you've taught me a lot. My wife is tired of me binging your vids today. See you soon.
As a sparky, I'm thoroughly impressed with your knowledge of 'lectricity theory & regs in 'straya. You even call them GPO's!
Great video, dude.
Thanks mate - I fall over at 'inductance'. (I know what induction is...) kVA vs kW is also a grey area for me. The stuff in this video was pretty basic - all homeowners should know it. Appreciate you watching.
@AutoExpertJC To John, was so right. As you explained so well, as being as ex spark, most wiring in most wire in most home in Australia is 2.5 cm for 10 GPO outlets
But most new home have 4 or more power outlet in each room. As I put out to most poaple, the RCD can up have to 20 point points. That just to start with and all doubt power point points. It doesn't stop there, as many have power points for the computer,, modern, print er and got into 6 outlet powerboats. That's not for study, but as well for lounge room the TV, top box and sound system. As you have kitchen microwave most of them 1200 watt, dishwasher , and exhausted fan. So most homes have 10 RCD and about 6 MCB for air-conditionings, hotwater service or heatpump now got RCD as work like aircon. As you was say you have 20 RCD with MCD. As most have 10 RCD for 2.5 cm wire. I have never been to you place, but having 20 Rcd on each breaker you most 4cm and had good electrician do wire. As most outdoor use 4cm wire, as light and power is on same cable. As you must have 40 power points or storage home. I read enjoyed your video. As love you to show why extreme come didn't color for different jobs. As one of your pet hates caravans using them in poaple back to live in. So can buy a RCDMCB cord so they kill them self or others. If you mind me asking where you got RCD cord as the old box type with behind power points
Cheers Bruce. I miss motor writer like you John from wheels and long passrd Wayne cantell . I don't waste money on wheel or motor
I would suggest that every extension lead should be as a minimum 3 × 1.5mm2. Anything under should be banned , they are dangerous to use. Regarding Gpo's 10A. or 15A, apart from the earth , they are inside exactly identical. You can easily draw 15A from a 10A Gpo, on a single circuit of course.
Totally agreed with all that. Just don't boil the jug on the same circuit as the 200A welder, contemporaneously.
One thing I would mention is that electric motors often found in air compressors have big initial power draw. It may be rated 10A and drawing as you said 9A during operation, but at startup, they could draw up to 7 times rated power. So not only you should refrain from running it via extension cord but if you do, do not plug anything else to it. Especially any electronic devices.
True of most electric motors, compressors in particular as cutting back in under load compared to the cold start from 0 psi/kpa
@@chriskennedy7534 It is true for induction motors even at no load. Just startup time is quicker but peak startup current remains the same on both load / no load cases.
@Piasecznik72 Do you think an AC compressor would agree?
In rush can be tricky to measure, easy life = happy
@@chriskennedy7534 Nothing that basic oscilloscope could not handle :)
@@Piasecznik72 I'll give you that, based on my limited oscilloscope experience, that's a wish list item.
But compared to the multimeter owners group, only one of mine can delve that deep, including a couple of watt meters
Good advice to avoid extension cords. If you need one for a fractional hp motor like a Dremel grinder, make up a cord that is sized for the load and make the cord as short as possible. 2 or 3 meters is often enough. If wire size needed is in doubt, bigger is better.
In the home workshop it helps to plan power needs against the power available. In my shop here in 'murica I run all 110/220v dual voltage motors wired to 220v to reduce the amperage draw. Think about what you have running at one time to avoid overloads. Watch the movie "Apollo 13" to see how this might be important.
Without having even started watching the video yet I thought I'd share my experience with extension leads and electrics cars.
I plugged my Polestar 2 into a 10A outlet expecting it to charge at atleast 8A, it was charging at 8A initially but overnight that dropped to 4A and the car was nowhere near as charged as I was expecting by the morning.. it wasn't until grabbing the extension cord (with a big sticker saying made in china and 10A/2400W on it) that I noticed it was notably warm.
As it turns out, most electric cars throttle their charging current based on the voltage drop of the incoming cable to stop them setting shit on fire, this is really useful when china are selling extension leads rated at 2400W with 0.6-0.8mm^2 wire in it.
I always use an extension cord with my compressor because I can hold the cord and keep my hands warm while I wait for pressure to build.
For an electrical dyslexic, numby, like me, this is a very well explained solution that many others should watch. Nicely done.
Thank you 😊
Besides the gauge of the wire, the condition of the connectors matters, especially at high current draws. Oxidation on the metal surfaces of the connectors will significantly increase the contact resistance and cause heating of the connector and voltage drop (that Ohm's Law thing). You should have mentioned that another issue with the use of extension cords is the increase the number of inline connectors.
I clean or replace the connectors on my power or extension cords whenever the metal no longer looks "shiny." If I have any question about a power receptacle, I just replace them. There are cheap and much less expensive than fires.
The power cords an many things are in my view inadequate. I would just replace the wimpy cord on the longer one of thicker wire gauge installing a proper wall outlet was not an option.
just use a surfacing disc on the conductors, if you can. At least that is what I do on 50 amp 250 volt plugs for my heavy use tools, in the USA. Even common 15a 125v ends aren't exactly cheap now, but I agree that if they are bad, it is no good. My dad taught me as a kid that wire size mattered, so it has never been a problem, but most people don't know any better.
Hey John, spot on as always on the physics. I worked supply festival power through my 30’s and I’ve given this same explanation to so many mobile caterers over the years. In actuality a solid 2.5mm H07 rubber flex extension cable should be a standard issue in any fatcave, and using something like that would never be an issue, but I get your point on the warranty adherence. I’d like to see some more shade thrown at the manufacturers though who could easily use 1.5mm (or better, 2.5mm) for their cords and give people at least a few meters…. But then there is the issue of some Darwin Award contender coiling said long power cord! That would be a useful video as it goes! Let me know if you’d want some input on that video, could help avoid some house and fatcave fires! Great work as always sir!
Thanks very much, Darren. I agree. If 2.5mm^2 extension cords (and power cords from high duty cycle appliances) were the standard, most of this would go away.
Coiled extension lead (in operation) = DIY induction furnace...
Fun fact: 2.5mm sq solid conductor has a lower current rating than 2.5mm sq flex cable. This is because the flex has more strands of finer wire to give that 2.5mm sq cross sectional area and therefore more surface area.
@@AutoExpertJC Not so much mate. The issue with the coil is the lack of airflow a bunched up cable has to get rid of heat.
there's little in the way of inductance 'in the coil' - because the return runs right next to the live... so the generated fields largely cancel out long before they interact with anything around them. running the 'return' next to the 'live' is a common practice in AC circuits to minimise emitted fields. The coils in your induction stove for instance all 'turn' in the same direction, just like those in a motor winding. if they had 50% of the turns going the opposite way, then you'd get no flux in the motor tooth, and no induced current (thus, heat) in your pan (or wire) and therefore largely mitigated inductance in that air coil.
you can do the test yourself if your willing... run 10A through 1 core of a coiled cable (use a dc power supply, for instance, no need for dangerous voltages, 5-10v will do plenty) and hold a magnet or bit of steel in the coil... you'll feel some of the electromagnetic force if you have enough turns coiled up. Now hook up the circuit such that it runs the same 10A back down the 'neutral' or 'earth' lines in the same 3core cable... you'll find far less (virtually none) of that force on the magnet/bit of iron. if you have an inductance meter, you can hook it up to the same 2 circuits, and see a dramatic difference in inductance.
@@sn0wchyld Yes, I don't think inductance comes into it to any significant degree.
@@sn0wchyld many extension leads have a helix. yes at domestic supply voltage the currents really arent high enough. but get a pair of high voltage wires evenly spaced and it can. swer systems have to have isolating transformers and bonding mats to control this inductance.
Any motor at risk of burning out from running too long is already poorly engineered. Not fitting a thermal cutout way, way worse.
I've had a few paper shredders that that do that, keep feeding them for too long and you've got to wait a while for the motor to cool down. It's a reasonable compromise. You can of course buy more expensive paper shredders with a 100% duty cycle. Many of the cheap welding units are the same.
It sounds to me like whoever made the air compressor being discussed is trying to circumvent Australian consumer protection laws and you seem to be taking their side. How can any consumer prove they didn't use an extension cord? Finally the voltage drop on a 20A circuit can be as much as the voltage drop of an extension cord using 1sqmm conductors. It's a function the resistivity of the conductor, cross sectional area of the conductor, r the current and the length of the conductor. Not all extension cords use all copper and not all motor windings use copper wire these days.
The reasons to run air hoses rather than extension cords on building sites and factories is for safety and cost. Extension cords have to be tested and tagged. Air hoses and air plumbing I think gets a free pass. Not to say compressed air is 100% risk free.
Excellent advice for diys that just bought a compressor to play with. Also If I remember correctly start up current on most electric motors is significantly higher for a short period which is sure to heat up those 1.5mm conductors. On the subject of Albo I cant really imagine him warming up the compessor to spray the box trailer and although I dont always agree with his politics I believe his heart is in the right place!
Rule-of-thumb. Motor start is 7 times the rated current. That is an unloaded motor ( eg. compressor is completely empty ) Some will draw less, some draw even more.
I’ve always known it as 9 times the starting current, but not really important. We have a few 400 kW direct online motors at our plant and that’s enough to dim the lights. And they are baby drives.
@@michaelslee4336 And those direct online motors will pull even more that 9 times. ( I assume you mean the load as opposed to reduced voltage starters )
Main place I've seen full load DOL starting on "Large" motors is in power stations.
One of the reasons why a soft start setup can be a good thing.
@@michaelguerin56 Have you ever seen a "liquid resistance starter? Or more so when it is starting?...😱 ( slight exaggeration )
You made a comment about topping up car pressures occasionally. So, does this mean leaving air pressurised in the tank?
I've been turning my compressor off and emptying the tank while cleaning up with a blowgun, then open the drain and leaving it open when not in use.
Thoughts about leaving a compressed air tank full at pressure indefinitely ?
John, i enjoy these tools and workshop safety videos more than car reviews.
You straightforward descriptions are excellent.
Don't forget, you throttle down your air with smaller air hoses just like smaller diameter electrical lines. So, while the coiled flex hose is handy it reduces the pressure you can supply to your air tool. Your couplers can also reduce the flow possible as well. So keep that line as big a diameter as you can as long as you can. First point you reduce the diameter you reduce the potential pressure everywhere past that point.
Well, pressure while flowing, yes. When all flow stops, pressure will equalize. But point taken.
It's a bit like running fire hose. You may have to put 180 PSI in to get 150 PSI at the nozzle. The same concept applies to dust collectors in wood shops and even home heating and cooling systems.
Oh hell yes. I sell plasma cutters which require a certain flow rate (185 - 230l/min) at 90 - 95psi and so many customers run 20+mtr x 5mm air hose and wonder why their cuts are slow, the parts don't last and the plasma faults out. That's if they have bought a big enough compressor to start with. I have a customer that I sold a CNC plasma table to with a 105amp plasma cutter, he has now bought 2 home handy man compressors and it still won't work properly. I wonder why...
This is why I make my own extension leads, using 2.5 sq mm arctic cable.... then I PAT them to be sure... (Portable Appliance Test)
2.5 sq mm cable is good for 20A and less voltage drop
Hey John, I've had the same Finnish made air compressor for nearly 30 years. Its rarely done any real hard work but it has a cord not just short but barely 50cm. I've always run it with a 5m or less industrial style heavy duty lead with a minimum of 1.5mm conductor and never had an issue. Its been incredibly reliable and is a good friend. I get a bit of rust juice these days when I drain the tank after use as she's ageing, is there anything you'd recommend to put in the tank to help neutralise the rust?
My Craftsman Compressor is over 30 years old too, I drain it frequently too.
who in the World measures Wire Dimeter with mm*2 Everything I have Ever Seen is AWG and it is your AMPERAGE and the Length of the Wire what will Determine What Size Wire AWG you need not Watts Not Voltage but Amperage it Don't matter What the Voltage is and Yes one horsepower is 750 Watts but that's with a Motor that is 100% efficiency and NO Motor is 100% efficiency so in the Real World we Say one horsepower Eletric Motor will Pull a Min of 1Kw or 1,000 Watts and can be More and Yes Volts Times Amps is Watts but for a One horsepower Running 110 Volts it will be a Min of 9.09 Amps if it is 120 Volts it will be a Min 8.333 Amps if it is 220Volts it will be a min of 4.545 Amps and if it is 240 Volts it will be a Min of 4.166 Amps. You can Run 75 Feet of 14 Gage or 14 AWG Solid Copper Wire know as 14AWG/3 and Run 15 Amp Breaker. if your Running 250 Feet and 15 Amp Breaker you'll need 10 Gage or 10 AWG Solid Copper Wires and I know I Say Wire but when I Say Wire I Really mean Wires and Yes you can Run only one Wire with AC and have Power is it the Right way to Wire up Things No but you can do it but you will need a Min of Two Wires with the Other one Going to Ground and to be to Code you Should have a Min of Three Wires one Black that is your Live/Hot/Power Line that is where your Electric Power is coming from one Wire being White this is your Common/ The Return to make a Closed Circuit and one Wire is Green this is your Grounding wire so if anything go's Wrong this will Flow the Electric to the Ground and Away from your Body. no matter what the Volts are Long as your not Running over 600 Volts For if your Running 600 Volts or More the only Difference you'll need to do is make sure the Wire is Rated for 600 Volts or More and has the Right Insulation on the Wire for that Higher Voltage other then that Normal Wire for Running Power Not Communications and there is a Formula for Length of Wire and Power Draw in Amps and Some of the Formulas have Voltage and Voltage Drop and heat Ect. but that is not so Important as what the Wire is made of and the Wire Dimeter/AWG or Gage and the Length of the Wire and how many Amps you'll be Drawing for the MAX Amperage you'll be Pulling at whatever YOU have Pugged in or Wired up and at Max Amperage you Shouldn't have a Voltage Drop of more then 3% to 5% So if it is 120 Volts you shouldn't have no less then 116.4 to 114 Volts when your Pulling Max Amperage and Yes Solid Copper Wire can Carry more Amperage then Stranded Wire but if your Moving the Wire around all the time like an Extension Cord you Should have Stranded for Solid Wire will Brake easier Moving and Bending around all the Time for if your moving it around all the Time and Bending it, it Should be Stranded Wire but Stranded Wire can't Carry as Must Amperage as Solid Core Wire and the Difference is not much but there is a Difference and it Can only be become Noticeable when you are Running High Amperage like the Max Amperage for the AWG and Length of the Wire for Long times So Soild Core to Stranded is not that Important Unless your Running that Zone or that Run of Wire at it's Max for Long Times without a Brake the Stranded Wire will get Warmer Sooner then the Solid Core Wire of the Same Dimeter or AWG/Wire Gage. and aluminum Wire of the Same AWG of Copper Wire no matter if it is Stranded or Solid Core Can't Carry as Much Power or Amperage as Copper Wire of the Same Dimeter/AWG and when your Talking about Long Runs and/or High Amperage it is Very Important you know What the Wire is Made of Copper, aluminum, Whatever but it Does Matter and it Matters Big So Don't Think an aluminum Wire of the Same AWG can Carry the Same Amperage/Power as if it was Copper for it Can NOT you'll need a Larger Wire Dimeter/AWG if the Wire is aluminum then if it was Copper Wire. and just Saying if you have Short Wire Runs Like 10 Feet and Less 10AWG Copper Wire can Carry 30 Amps Safely and the Shorter it is the More Amps it can Carry Safely like if you have a one foot Long 14 AWG Copper Wire you can Safely Pull 15 Amps not Stop 24/7/365 and Up to 30 Amps for 10 Second or Less Short Brust and if you have 10 foot or Shorter Length of 12 AWG Copper Wire you can Safely Pull 20 Amps 24/7/365 and up to 40 Amps for 10 seconds or Less Short Burst and Yes it can handle Longer Burst then 10 Seconds and not Burn up but it is not Safe to do so over the Longer Lengths and/or Higher Amperage just like for you can Safely Pull 50 Amps or even 100 Amps for 1 Second or Less on a one Foot Long 10 AWG Copper Wire but if you Take that Same 10 AWG Copper Wire and Pull 100 Amps for Minutes, Hours or Days or Seven Days you'll have not only a Hot Wire but you'll have a Melted Wire and Maybe even a Fire. Good Thumb of Rule for Wire Size to Amps your Pulling is for Every Even Number AWG you go up it Take Two Wires of the Next Step Down in AWG Even Sizes So Two 14 AWG is one 12 AWG, Two 12 AWG is one 10 AWG, Two 10 AWG is one 8 AWG, Two 8 AWG is one 6 AWG, Two 6 AWG is one 4 AWG and so on and So on and this Don't Mean with 14AWG/2 one White and one Black or 14AWG/3 one White, one Black and one Green is one 12AWG That is NOT What I am Saying for What I am Saying is if you have Two 14AWG/2 so you have Two Black and Two White 14 AWG or Two 14AWG/3 That would be Two Black, Two White and Two Green that would be = to one 12AWG/2 or 12AWG/3 that would Mean you have One Black and one White of 12 AWG or 12AWG/3 one Black, one White and one Green of 12AWG. Every Time you go up in AWG in Even Sizes it is Equal to Two of the AWG of the Size Below Keeping in Even Sizes and if you need Two Wires of 10 AWG Say White and Black or Black and Red and all you have is 12 AWG you'll need Four Wires Two White and Two Black or Two Red and Two Black. So Every Time you go up in AWG in Even Sizes it Double's in Dimeter but it don't mean that one White and One Black or one Red and one Black of 12AWG is Equal to 10AWG for it is NOT!!! you would have to have Four Wires Total Two Red and Two Black or Two White and Two Black of 12AWG to Equal Two Wire Total one White and One Black or one Red and one Black of 10AWG
Make yourself a 2.5mm extension lead 🤣
As a sparky I'm really happy with John's understanding of volt drop, the explanation etc. It's perfect.
yeeep, the piss poor copper clad alu (or worse iron!) chinesium wires commonly sold around the world today is a disaster. Discovered the hard way while building a high power UPS/Emergency power supply based on SLA batteries. The wires lost a ton of power = copper clad alu = twice the losses (and more!) than true copper wires. B'cuz losses, they also start to quickly heat up = increasing losses during use.
Why? Because they've used the SMALLEST gauge/size they can get away with and don't want to compound the problem with the user/customer's cord!
I have installed dump valves on all but one of my pneumatic outlets.
It saves a lot of time not having to turn the outlet off then bleed the air out of the hose before disconnection from the outlet or the potential damage to a person's hearing.
Love your videos.
Also I'm 99% sure you can pull 10 amps max from each side of a double GPO unless limited up stream by a circuit protection device.
Generally that double GPO is feed by a 16 Amp CB ( or if rally old rated for a 13 amp fuse wire ) and usually that circuit has more that one outlet fitted. Most 15 amp outlets are also protected by a 16 amp CB but no other outlets on the circuit. The wire is rated at 20 amps if 20 meters or less from the CB. Long run, up the cable size. ( yes, 20 meters CB to GPO plus Ext lead( whatever length ) exceeds that rating ).
@@alanhilder1883 If there are other outlets on the circuit it just means the fuse or circuit breaker trips sooner if they (the other outlets) happen to be in use at the time.
Auto Expert John Cadogan.. Nice video. New subscriber here.
Another great video John. My local hardware store sells 15A extension leads (1.5sqm) but with 10A plugs which gives another option to offset potential voltage drop without breaking the bank.
yes so called trade duty leads. many builders hardware and tools shops have these.
Great John , easy to follow for everyone.... well maybe except for Albo ! He's still struggling with his 27 pages ... oh I mean 1 A4 page sshh sorry Albo did I let the NO out of the bag 😂😂😂
Being a scientist I fully understand the physics from a classroom perspective. Thank you translating this to the real world. I often wondered why no extension cord and your explanation makes perfect sense. You are also funny in your delivery and makes it even more enjoyable!
The "bad" cord you shown 13:30 is not the worst, the market is flooded with 0.5 mm2 and 0.75 mm2 wire cords rated for 10Amps. I actually measured the wires in one, and they ware ~ 0.38 - 0.4 mm2 and rated of course for 10 Amps. Gone are the days of 1.5 mm2 wired cords rated for 15 Amps that everyone considered junk.
Lie in bed awake and get this into your head. Once you get Ohms Law worked out it will be a light bulb moment when it'll all make sense, so useful. ( maybe not in bed but with pen, paper and a calculator ! )
True, but straight Ohm"s Law is only truly accurate for Direct Current (DC). The Alternating Current (AC) motors on the compressor are inductive loads and therefore the power factor has to be taken into account. It will not introduce a significant error, but just saying for awareness.
When I was a novice carpenter I never grasped Ohms Law well enough to remember it until I found myself staring at the label on a 4 way adaptor & had an epiphany. 240 volts @ 10 amps = 2400 watts. Aha! So 240 watts is 1 amp! So, 120 watt thing @ 12 volts is 10 amps! That sort of set the meaning of the relationship of the values for me. Being able to calculate tool & component loads relative to supply quickly is vital when every day's set up is different. To this day I still picture that label on the 4 way for a fraction of a second.
Very well composed video for your specific power management regional standards. But this does not apply to many countries, since plugs can be very different, as well voltage and amp standards. This needs a quick summary, e.g. use at least 1.5 mm2 wiring for 2kw compressors, 2 mm2 wiring for 3kw compressors, etc... . Just like a good user manual, this needs to be simple-stupid because we are dealing with safety.
As a former Bunnings employee who worked in the toolshop and did the warrenty claims, buy the right compressor for the job.
The Ozito oil free compressor is great, but not suitable for dusty environments and constant duty cycles. It's designed for pumping up tyres, balls and blowing the dust off the bench. Drain the water after every use and it'll last 20 years.
If you plan on using thirsty rattle guns, working in a dusty woodwork shop or a daily driver with the air tools, get an oiled compressor with proper air filters. If you're not sure, rent one! Rent a couple, find the one which works for you.
I THINK possibly the other safety aspect is that an electrical extension cable can be damaged etc and be a extreme/fatal hazard whereas an extended air hose does not pose such a harmful threat (not saying NO threat…diminished threat) 🤔👍🇺🇦👍🇺🇦
A tip from another content provider who had tanks explode is never buy a compressor with a seam weld at the lowest point. Internal condensation will rust out the weld faster than sheet steel.
The greater problem is that the tank being made in a certain country to specifications totally inadequate and very very little safety margin, not that the seam is in the bottom of the tank.
Are the ends not welded all around, so there is always a weld at the lowest point ?
I answered and said, "If I have found favor in thy sight, O Lord, show this also to thy servant: whether after death, as soon as every one of us yields up his soul, we shall be kept in rest until those times come when thou wilt renew the creation, or whether we shall be tormented at once?" 76 He answered me and said, "I will show you that also, but do not be associated with those who have shown scorn, nor number yourself among those who are tormented. 77 For you have a treasure of works laid up with the Most High; but it will not be shown to you until the last times. 78 Now, concerning death, the teaching is: When the decisive decree has gone forth from the Most High that a man shall die, as the spirit leaves the body to return again to him who gave it, first of all it adores the glory of the Most High. 79 And if it is one of those who have shown scorn and have not kept the way of the Most High, and who have despised his law, and who have hated those who fear the Most High -- 80 such spirits shall not enter into habitations, but shall immediately wander about in torments, ever grieving and sad, in seven ways. 81 The first way, because they have scorned the law of the Most High. 82 The second way, because they cannot now make a good repentance that they may live. 83 The third way, they shall see the reward laid up for those who have trusted the covenants of the Most High. 84 The fourth way, they shall consider the torment laid up for themselves in the last days. 85 The fifth way, they shall see how the habitations of the others are guarded by angels in profound quiet. 86 The sixth way, they shall see how some of them will pass over into torments. 87 The seventh way, which is worse than all the ways that have been mentioned, because they shall utterly waste away in confusion and be consumed with shame, and shall wither with fear at seeing the glory of the Most High before whom they sinned while they were alive, and before whom they are to be judged in the last times. 88 "Now this is the order of those who have kept the ways of the Most High, when they shall be separated from their mortal body. 89 During the time that they lived in it, they laboriously served the Most High, and withstood danger every hour, that they might keep the law of the Lawgiver perfectly. 90 Therefore this is the teaching concerning them: 91 First of all, they shall see with great joy the glory of him who receives them, for they shall have rest in seven orders. 92 The first order, because they have striven with great effort to overcome the evil thought which was formed with them, that it might not lead them astray from life into death. 93 The second order, because they see the perplexity in which the souls of the unrighteous wander, and the punishment that awaits them. 94 The third order, they see the witness which he who formed them bears concerning them, that while they were alive they kept the law which was given them in trust. 95 The fourth order, they understand the rest which they now enjoy, being gathered into their chambers and guarded by angels in profound quiet, and the glory which awaits them in the last days. 96 The fifth order, they rejoice that they have now escaped what is corruptible, and shall inherit what is to come; and besides they see the straits and toil from which they have been delivered, and the spacious liberty which they are to receive and enjoy in immortality. 97 The sixth order, when it is shown to them how their face is to shine like the sun, and how they are to be made like the light of the stars, being incorruptible from then on. 98 The seventh order, which is greater than all that have been mentioned, because they shall rejoice with boldness, and shall be confident without confusion, and shall be glad without fear, for they hasten to behold the face of him whom they served in life and from whom they are to receive their reward when glorified. 99 This is the order of the souls of the righteous, as henceforth is announced; and the aforesaid are the ways of torment which those who would not give heed shall suffer hereafter." 100 I answered and said, "Will time therefore be given to the souls, after they have been separated from the bodies, to see what you have described to me?" 101 He said to me, "They shall have freedom for seven days, so that during these seven days they may see the things of which you have been told, and afterwards they shall be gathered in their habitations." 102 I answered and said, "If I have found favor in thy sight, show further to me, thy servant, whether on the day of judgment the righteous will be able to intercede for the unrighteous or to entreat the Most High for them, 103 fathers for sons or sons for parents, brothers for brothers, relatives for their kinsmen, or friends for those who are most dear." 104 He answered me and said, "Since you have found favor in my sight, I will show you this also. The day of judgment is decisive and displays to all the seal of truth. Just as now a father does not send his son, or a son his father, or a master his servant, or a friend his dearest friend, to be ill or sleep or eat or be healed in his stead, 105 so no one shall ever pray for another on that day, neither shall any one lay a burden on another; for then every one shall bear his own righteousness and unrighteousness." 2 Esdras 2:31
,,,''''
oh boy, I thought you were going to talk about how these air compressors get a little explodey when you don't drain them and get rusty.
Might save that for another day. (My oldest compressor is behind a brick wall...
Also the plugs/GPO are a 'restriction' too...
If you feel the cord on something drawing a lot of current, and then feel the plug, you will often find the plug is much warmer than the cord in general. Just something to be aware of, and use longer and fewer extensions as possible.
Hopefully only one extension cord at most, and I would never use any more than two...
Awesome explanation as always JC. I have used a 20m, 15amp lead with 10amp plug daily as a chippy for 30yrs on a good old Aussie made Pilot belt driven air compressor with no dramas. (1650watt motor) I have it bolted inside a tool trailer, so it is a bit of a job to remove and is a two man job to pull out and carry to get close enough to a GPO. We find the belt driven type compressors start up a bit easier than the smaller direct drive units on cold frosty mornings when the air is cool and dense, but the downside is it always lives in the trailer.
Just don't coil up the excess lead somewhat neatly, that will cause massive problems. I was working near some boilies using one of those small, lightweight welders ( not the problem ). The boilermaker was complaining that the welder was playing up. I had a look. The welder was near enough to plug into the gpo ( powerpoint ) but they were using a ext lead, ( 15 a rated cable ) coiled up neatly. That lead was getting quite warm. Plugged the welder in without the ext lead, worked great.
And I’ve been using my belt driven 15amp plugged air compressor for 20 years on 10amp GPO’s with 10amp extension cords without one issue and it never gets remotely warm 😂. 🤫
Yes but the Pilot is a PROPER tool with a motor with a proper starter capacitor circuit etc....The compressors Mr Cadogan is reviewing are not well designed and have great internal inefficiencies.
@@Warpedsmac ooh this makes absolute sense to why I’ve always had zero issues skirting around technicalities because I generally always buy the best quality tools I can. Sometimes you just forget how much average, cheaper quality stuff there is out there on the market that cannot be compromised.
@@NatesToolbox Yep, we use various direct drives as well and like you run fine on extension leads, except some brands won’t start up on cold frosty mornings, but then they are light enough to pickup and plug into the meter box and all good.
Yeah you would want to use a heavier cord rated for the amperage draw of the device you're using at least something a little higher to give you a cushion so you're not endangering the plugs cuz the plugs also will be your main failure cuz I've seen it before we're yet the device said it can handle 15 amp draw but I seen the plug slowly change color on the wiring in the coating that was on the plug going from Gray to a brown and becoming extremely hard and it was only carrying just the maximum limit! On that extension cord so I always recommend to have a cord that can go higher amperage than what you're really needing so you're not blowing up your plugs
does this mean we are one step closer to a bin cam? 😅
Several steps in that case...
I was asking myself this same question.
Install a 15 amp outlet (socket, GPO? whatever) (IPxx weatherpoof) on the wall with a dedicated 2.5mm2 cable on it's own breaker (DIY of course because why not) and plug in whatever you want with a 1.5mm2 extension with 15 amp plug and socket (DIY again) and everything's good. Hell while you're at it charge your EV at 13 Amps, but wait, there's more. Hardwire another 13 Amp EVSE brick and charge 2 EVs at the same time. Just make sure you actually know what TF you're doing and make sure the cable has plenty of free air around it and limit the total current to 25 Amps which is what 2.5mm2 will handle.
I'm slowly building up to a decent work shed. I bought a fixer-upper house and over the past 3 years i've found it's better to do the work myself, hence the tools getting purchased. This has extended into doing my own mechanical work with my car and motorcycle. I just bought a torque wrench last year, and my next purchase is going to be an air compressor. So, perfect timing in the last two videos from you. Thank you.
I did the same here. i don't like to hire people to do the jobs that I can easily do.
Especially these days, these "professionals" are really ripping people off with jacking up the prices to stupid numbers.
Eg. I got a company to quote me on replacing the sewer pipes in the basement.
The ridiculous quote was about $19,000 dollars!!!!!
I bought the materials that I needed, INCLUDING a jack hammer and piping.
I did the entire job in 3 days (yes, I'm slower than they are) and my total cost, INCLUDING the jack hammer, was about $400 ish dollars!!!
My attitude is that if someone else can learn to do something, so can I.
It's worked out well.
As for the compressor, however, at some point, I want to replace mine.
Not that it's not working right or anything like that, but that it's old now and I have to assume that the tank is rusty on the inside. When that happens, these tanks can explode and take out a wall or kill a person if close by. I've seen videos on that.
So the next air compressor I buy will have an Aluminum tank!! No rust to worry about.
As for my tank, I've been lazy, because to confirm what it's like inside, I just have to remove an end cap and stick the borescope into it and have a good look to confirm if it is in fact rusty or now.
It's fun to do things ourselves and save $$$.
@@BlondieSL Old air compressors are some of the best. Mine is at least 30+ years old and the other one is a 1947 model. I rebuilt the 1947 model pump and bought a new steel tank, without epoxy lining. Epoxy can help the rust. My auto drains are tied to the pressure switches. The tanks drain the water every time the pump cycles and only when it actually runs, so I never have to think about it. The newer one has a rusty tank. Explosions are rare and usually they just leak, but I have considered replacing the other tank. Check out the Garage Journal Forum, if you haven't already. It is for guys like us that DIY, are pros, and do mechanical stuff. I am a pro in multiple trades so stuff like the electrical talk is old news, but it is all true and relevant and garage journal has been a great resource to learn more, especially about equipment. There is so much information on air compressors, bench vices, and anything else you can think of, from people from all over the world. Cheers!
@@CGT80 Thank you! I will check out the Garage Journal. The site looks interesting!
As for my compressor, as soon as I can get mobile again, I'll check it out inside and if it's not rusted out, I'll keep using it.
But I'm contemplating preparing 2 or 3 old 20 lb propane tanks to add to its capacity.
But I need to add these tanks with a quick release option so that I can move the main compressor in and out of its location for oil change and such.
John, did you mean "No Blow Albo" from CanBranistan?
I've got a problem with your comment that "the motor current must increase as the voltage dropped". Youre using the P=IxE formula in a way assuming P is fixed. Its not.
You must factor in thats its no longer a 2Kw motor when supply voltage drops. The 2Kw is a name plate rating only assuming supply of nominated nameplate voltage.
I think if there is rise in current it would be due the drop of rpm as the rotor and stator are getting out of sync due to the loss power supply.
Another factor to consider is starting current. Usually about 4 times FLC. Getting the started thru the 1mm ext cord is a big issue. When your 5 amp motor sucks 20 Amps at kick off.
Your explanation of house wiring and ext cords is top notch. Dont forget HPM has 2.5mm ext cords as well.
If you are going to make assertions, as you have. You better get your facts correct next time. Start Current on a standard Induction motor, (single phase) with capacitor start, is closer to 7 x FLC. P is determined by demand, P does not decrease as voltage drops, A increases as V drops, this is why leads cook and motors trip overloads, whether they be manual restable or auto resetting thermal overloads. Again, P is determined by demand, especially for a positive displacement pump, which is what a compressor is.
It gets even worse in the US, where the standard wall outlet is 120V 15A. That's theoretically 2.4 hp, but practically you can really only run up to 1.5hp motors. 240V is available, but most houses just have couple of outlets for a stove and a clothes dryer, so if you want to run a 240V compressor, you'r probably going to have to install an outlet for it or hard wire it. The good news is that extension cords of up to 12AWG (4mm^2) are readily available. Of course you need that thick, expensive wire if you're running significant power at 120V
Hi John, On a slightly related note I'd be interested in a video regarding air compressor vs battery tools for DIY mechanic use, particularly an impact wrench. The pros/cons, costs etc. Greetings from the UK.
Generally battery for the win. But you get locked into a brand's ecosystem...
Air tools are nowadays cheap, reliable* (if maintained), scalable for agricultural or construction use and multi use. Batteries are portable, plug and play, no leads, quieter and low maintenance. Batteries are more suited for home duty and trade with passenger cars, Pneumatic still has advantages for Mining and Agricultural machines that require more oomph.
Battery 1000% better, air is more powerful at the high end but I've never come across something my Dewalt mid torque can't undo and if I ever do they make a high torque that is significantly more powerful again. So much more convenient, quieter, easier, Price really is up to you, the cheapest battery stuff will be cheaper than the cheapest air system but both can be very expensive if you want quality. Air tools are pretty much a lifetime tool, battery not so much but they do last a good while especially for a home gamer. I chose Dewalt because Bunnings sells it and is both close and open late, it's also cheaper and close to as good as Milwaukee which would be the money no object choice. Other people have lots of luck with Ryobi though and it is definitely the bang for buck choice
@@aslkdfjhg Air power has its niche in things like some industries, agriculture and mining because they work with so much stuff that can blow up given enough sparks and fire.
Coal, grain dust, gasses and various vapours all can contribute to a local extinction event for the region.
For the average mechanic you're probably better off with electrical for the most part for ease of use as compressors do need some kind of maintenance cycles of oil and cleaning out the cylinder sometimes. Course if you're doing very heavy work on site based machinery or large vehicles all day, air can come in handy for heavy lift jacks and stuff too. Or if you end up being the lucky prick changing about a billion lug nuts on a truck or something
There are some things that pneumatic is the only option, battery stuff is very convenient for reducing noise and not walking around tethered. I use both, I perform many different tasks.
TLDR: Just use a beefy extension cord that’s not longer than necessary with decent wire thicknesses.
I get that you tried to keep the story short but a big issue with all single phase capacitor start motors is the high starting current that is drawn momentarily on switch on, typically 5-7 times the full load current stated on the name plate of the motor. Any excess volt drop while starting extends the time taken for the motor to reach operating speed and stresses the motor starting winding and the starting capacitor both of which have short time ratings. (If the starting time takes too long your circuit breaker will trip and the compressor won't be able to run.) These short time ratings for the motor starting components are why single phase motors are specified with a maximum number of starts per hour. If using a single phase compressor with high air consumption tools you need a compressor with a continuous run operating mode otherwise your motor will eventually die if it is repeatedly cycled on and off by the pressure switch. My solution was to make my own extension lead out of 2.5 mm sq. flex so the rate of volt drop in the lead is the same as the rate of volt drop in the wiring in the wall.
I think that's the ideal solution. I appreciate the tips about the surge on start - explains why I've never been that successful running a compressor with a battery-inverter system.
Bunnings "caravan" 15A extension lead (2.5mm2) with an 11A RCBO adapter to the 10A GPO.
@@AutoExpertJC The same situation exists meeting starting current requirements with electric motors supplied from a small generator. Power tools with built in electronic speed control or soft start are usually no problem but any machinery with single phase induction motors running from a generator need the generator output rating to be several times higher than the motor name plate rating for trouble free starting without undue stress to either the motor or the generator.
Wondering if you did do the multiple cable trick that you mentioned, putting a watt/power meter directly on the GPO, and then a second time putting the meter after your 15a cable and measure the actual 2 voltages.
If you're still getting 215-220 out, it should be fine. If you're getting 190-200 on the power meter, then you know the voltage drop is likely to cause damage.
That was a great video. Living on a houseboat and seeing what some people do for power is quite scary. We have a 15A pole and plenty of boats run a piddly little lead. Same with the lead from generators. People need to realise that extension leads have a lifespan and replace them as required. Also if you suspect power points have been installed unlicensed, get a sparky in to test it all. Still can't beat that Highway Patrol Tesla charging lead though.
It really depends what consumption devices are in the houseboat (ie - drawing 5 amps on a 10-amp lead is no problem. Drawing 12 is a huge issue.
Hi John, are there other devices which should not be used on extension cables? I expect portable EV chargers would have similar issues. John
Isn't a portable EV charger called an ice driven generator?
Gday John,
70yr old hospital sparky technician here. 100% spot on mate. Spent many hours teaching this stuff to people for 40yrs. Great stuff thanks.
I just love it when an atheist calls out, "Jesus!"
You have touched a very interesting point: GPO with a 10amp rating protected by a 20A circuit breaker! A sure recipe for a fire death! As mechanical engineer i have had stand-up fights with my electrical counterparts and I thiink regulations must be updated!
So you'd like one 10A gpo per circuit on a 10A breaker? So maybe 20 power circuits per house instead of 2?
My dad made up an “extension cord” out of what looked like 4awg (coulda been 5, but close enough) stranded, so you could actually coil it. It was heavy, made of “ found” wire, but nothing got hot and nothing ever died, including humans. It was a bear to haul its 50 ft length. But it was safe. He was among other things, well versed in electricity and passed along the wisdom.
As a sparky, I say this is all good advice, and yeah I wouldn't be concerned with using an extension cord on the odd occasion, especially on a small air compressor such as this.
If you really do need more length in a permanent position, just get a sparky to replace the pissy flex lead with a heavier 2.5mm2 flex lead.
Great video John small point about cross section increasing flow of Amp or fluid being related to R^2 . The Radius Squared has a huge effect on the flow so a 1 square is not half a 2 square cable.
Fascinating how science now suggests more energy travels around the wires, than through them, Def not the case with the liquid analogy
@AutoExpertJC there are 2 other reasons to be cautious, one more subtle than the other.
1/ People often use extension leads partly on a spool, which causes overheating of the cable on the spool, more resistance and more voltage problems for the compressor.
2/ a coiled cable has inductance, especially if there is iron close to it, and that causes a voktage drop with phase shift (minor I will admit) and the compressor sees lower effective voltage and higher current again, to achieve the same power.
Or, in the worst cases, all these things add up and the compressor fails to start, making a buzzing sound until it rapidly overheats. Only seen this once, but the smell was 'orrible!
I don't buy the "inductance" point. The currents in the conductors (live and neutral) are balanced, and unless you've taken extraordinary care managing the twisting of the cable, the orientation of the conductors with respect to each other in adjacent turns will be random, leaving the coil with close to zero inductance. (Close to, not exactly zero, because it will still have at least the inductance of essentially a shorted transmission line.)
Speaking of compressed air, in the dream time I was the Maintenance Manager of a drilling company during the "arms race" of ever higher air pressure for precussion drilling, at the start of 1990 900cfm @350 psi was "big air", at the end of the 90's, it was 2 x 1350cfm compressors feeding into a booster that increased the pressure to 1000 psi. It was like the Apollo program, a lot of failures along the way but now the norm and exponentionally increased the penetration rates and the depths of compressed air drilling, 1990, 120m depth, 1999, 450m depth. That being said a lot of diesel getting burnt to drive all of that, 2500-3000 litres a shift, we wouldn't have got a Christmas card from Greta.
Wow! That is some big stuff. I have a "little" 5hp 17.3 cfm at 175 psi westinghouse air brake company compressor. It is small for the series that went to 25hp or so, but with a motor at 109 pounds and a pump easily the size of a motorcycle engine, it is big compared to many home shops. My uncle had the 25hp version for the blast cabinet at their abrasive blasting shop but they ran 125 to 250 cfm diesel units for blasting rotors and parts for power plants in the western USA and Hawaii. I have only seen 1,000 cfm units on trucks in SoCal but haven't seen what they are used for or anything bigger. That is cool stuff and would have been fun to learn about.
Fun fact: if you're hose is super long (no pun intended) and your application needs large volumes of air you'll experience a pressure drop through the length of the hose too. Either way you're screwed 😅. Great video and explanation, although I know how it works I could never explain like you do.
I would think inductive effects would be very minor, as current is flowing in opposite directions in the two conductors, so magnetic fields should mostly cancel out. But having all that wire coiled together with no room for air to circulate around it is definitely going to make it get hotter.
how are they going to know if you used a ext cord?
Great video, very well explained. Given the compressor theme, how about a video on the different types of fat cave compressors, pro cons, including the sweet spot for decibel output. Some are horrendously loud.
A bigger more efficient silencer is quite easy to make.
Good advice, I've always made my own heavy duty extension leads, fine for welding and compressors.
So the five white 5m extension cords I have joined together, off the double adapter, that also has a double adaptor into the $9.99 power board (such a great buy), that’s attached to the other power board dad used in the shed when I was little, that still worked good after the flood of ‘83, that’s plugged into that power point I put in, running off the old light bayonet in the shed roof that dangles a bit, but it’s ok because it goes back to the fuse box where I swapped out the 10amp fuse with a bit of old coat hanger wire and that’s all powered the compressor fine, except that time there was a small fire, but then I was able to repair the insulation with some duct tape that was left behind by a tradie, oh shit I forgot to take a breath!
…Boom!
You just buy a 10 amp 3 pin plug and fit it to the 15 amp extension lead.
Done that.
Also dismantled old triangle shaped double adapters and modified the earth slot(s) with a hacksaw blade to accept the 15A plug - no expletive ridden argument with getting heavy cord into 10A plugs.😂
FWIW, I live in the U.S.A. Many years ago I bought a 120v MIG welder. I needed an extension cord for it so I added the matching 15A male and female ends to a 50A R.V. extension cord. Yes, if you tin the wires you can fit them correctly into the terminals without fraying. I also use this cord for a more recently gifted 120v air compressor. In the last 15 years of use I have never had an issue with either the welder or the air compressor.
This is a problem with the kind of compressors available at what Americans call a "box store". Supercheap Auto WallMArt, Costco, Bunnings, Repco, Mitre 10, Aldi, Big W, etc even Sydney Tools sell some cheap ones . This problem does not occur with a decent compressor...AND this problem IS NOT LIMITED TO CHEAP COMPRESSORS.
I'm a retired electrician
I think the warranty "assumes" that any extension lead is going to be no more than 1.5mm
There would be no difference electrically between having a 2.5mm fixed wiring run out to your garage with an outlet on the wall, and a 2.5mm extension lead, just make sure the extension lead isn't coiled while in use
Keep extensions as short as possible, it's best to have several shorter ones that you can daisy chain if you need them longer.
My answer if i couldn't install fixed wiring would be to use a 2.5mm extension, but tell the service dept that it was plugged in to a fixed socket, i'd like to see them prove otherwise.
I regularly made extension leads with 2.5mm cable, mainly for steam power washers around the farm buildings.
btw, there will ALWAYS be volt drop, but the thicker cable reduces how much, put a voltmeter on your socket and compare when the compressor is on or off
@JC - The take away (long story short): (resistance is futile - comply w/warning label): use an air hose extension.
Never ever buy pissy extension cords. All my cables in and outside the wall is minimum 2.5 m2. 1.5 mm2 is rubbish in my opinion. The difference in price is minimal. In Switzerland we have 230 V 13 or 16 A.
Yep. I years ago replaced the primary cord on my (long past warranty) Craftsman 5 gallon compressor with 20 fee of 10/2 AWG Romex going to a 20amp wall outlet. Plenty of current room as well as enough cord to go anywhere in the garage..
Damn!!!!.........I bought a new shop compressor a year ago and had forgotten about the "No Extension Cord Warning"......thanks for the reminder.........
When I was living in Perth a few decades ago a stupidton had a problem with a fuse always blowing. His solution was to twist a 3 inch nail into the fuse spot. The fire brigade found the 3 inch nail in his power box when they investigated the cause of the fire which burnt his house down.
Perfect - that's called a 'self-levelling system' in the context of evolution.
Otherwise known as a 1000 Amp no blow
Brilliant deployment of a 500-amp fuse, when you think about it. Just failed to upgrade the rest of the circuit.
I would say that having the option to plug in a 15amp cord into a 20amp outlet is also just as wrong as the other way around since you can actually overload the cord with too much current, The standard we have here is always that the total circuit fuse can´t go above the weakest rated wires in that same circuit, we normally have more fuses in the main fuse box instead and they will pop before any outlet can be overloaded no matter what kind of extension or load we connect. we have but one kind of power plug for 230V and our standard 3-phase for bigger stuff.
Thanks John for all the useful comments, which I'm sure most people will find eye opening and helpful. I hope you don't mind but, I wanted to add a few comments to supplement your info.
I am in the US where the mains/line voltage is 120 and 240 volts. Most low cost compressors 1.5 hp and less use 120 volts. Most of these compressors use a single phase induction motor, which has poor starting ability and is very touchy about input voltage. Rated induction motor input voltage in Australia is 210 to 250 volts but, the motor runs cooler if run towards the higher end of the range; like 240 volts. Starting surge current is about 10 times the run current so, I would highly recommend an extension cord with 2.5 mm2 wire. If the manufacturers of compressors made for jobsites really knew what they were doing, they would use a brush motor, which has has no problems running on lower voltage (except output power naturally drops). Duty cycle on these low cost compressors is about 20% so, between using an undersized extension cord and running the compressor in full sun on a hot summer day, stands a good chance of over heating the compressor if you are constantly emptying the pressure tank. Motor efficiencies can be quite poor on low cost compressors. I have seen efficiencies as low as 30% with a 0.55 power factor. Although, most efficiencies run 50 to 70% with 0.6 to 0.95 power factor. And to conclude, I guess one of the best kept secrets related to compressors is the air delivery ratings: which measures the compressor suction airflow rate, not the output flow rate as one would automatically assume.
I have a question for all you experts. I have a shed/workshop 30m from my house, Power is from an insulated outside 2.5mm cable.
I don't worry about overloading the supply, my reasoning is that I only use one tool at a time. Plus The radio. Wrong or right, This has served
me well for many years and I'm not looking to change it. Question is how would I fit a smallish compressor to a setup like this?
U.K 240v supply. Thanks.
This advice also goes for your welders, especially, if you can't seem to spray electrons and molten BB's in any decent manner. Voltage drop at high electrical loads could be the culprit, or you just suck at welding. 🤣
Heheheh.
As YOU SAY @ 22:28..
Just buy/make a fkn long airline!
Geezuz!!
Its air science!
Not rocket surgery!
I’m a long time stalker…
Love yer work Mr. C..
Thank you John excellent information to keep us safe in the workshop. Cheers
What is the AWG of the power cord? Voltage Drop is affected by length of conductor. I prefer 12/3 extension cords to accommodate multiple loads. A 4 outlet box with a GFC helps. One of my extra jobs in the Navy was inspecting electrical items in my squadron, personal and tools, and either certifying or confiscating them. Wires get stretched and insulation wears out, so simple tests and inspections improve safety and performance.
YOU ARE SO WRONG...
Just because you are!
But im not sure which part...
Other than that...very well explained ❤
At tech we got told about the water in a garden hose analogy. The water in the hose is the current and the speed at which the water travels is the voltage. Crimp the hose at any point and this will create a resistance and slow the water down, this is just like a voltage drop.
Plug into the garage 120VAC 20-amp outlet and charge the tank. Roll outo the vehicle and fill the tire. Have used thextension cord many times. No problems.
If you must use an extension lead, always unravel it. Never leave it coiled up.
By using an extension cord, all that you are doing is installing a resistance in series with the impedance of the motor. This won't hurt the motor in the least, but if the conductors (wires) in extension cord aren't of sufficient cross sectional area, they will overheat and possibly cause the extension cord insulation to melt and burn thereby igniting your home and leaving you destitute.
As for the compressor, it is simply receiving a bit less power from the circuit breaker because some of the power flowing through it is being used to heat up the extension cord. So, get a beefy extension cord and you'll have no problem.
In the US, we typically have 16 AWG, 14 AWG, and 12 AWG extension cords available. AWG stands for American Wire Gauge and the smaller the number, the larger the cross section of the wire. 16 AWG conductors are 1.31 mm^2, 14 AWG conductors are 2.08 mm^2, and 12 AWG conductors are 3.31 mm^2. Basically, for every decrease of 3 AWG numbers, the cross sectional area doubles (but you rarely see wires produced in odd gauge numbers). You might note that these extension cords seem large by Aussie standards, but that is because our standard residential power is at 115 VAC rather than the 230 VAC used in Aus., so we need double the current to deliver the same power at half the voltage as you all use.
In any case, I've used extension cords to power a small home compressor many times on many projects and never had any problems, but my extension cord which should have been a smaller gauge did get fairly warm to the touch. Since I was always working outdoors with the extension cord laying on concrete, it wasn't really a safety concern to me.
Spot on, thanks for the valuable video. I sat down with pencil paper and calculator to determine the compressor needed and 2 hp would work safely. A friend of my complained that the 5hp compressor would not work. I tried to explain to him all of this . In America normal find 120V and 15amp circuit. Best Regards!
Yep, sounds about right, only thing I would add is that it's generally the startup current of the PEM motor where you come unstuck, as the small gauge wire can't deliver the large inrush current the motor needs to gets started and that's how the windings in the motor get burn out.
Thanks. Love this video John. 1976 I think it was I got a call. "The refrigerator you sent us is not working and our beer is not getting cold". Ho hum it was working fine when we pre trip tested it yesterday.
So off I go and low and behold there's our perfectly good refrigerator with a 30 metre lead connected to it still wound up on the ground with the sun shining directly on it.
Lots of other stories like this especially to keep the beer cold in my army days as an electrician.
Enjoy your videos but a little hesitant to leave comments as my grammer is not that crash hot.
Russell.
Thank you very much, Rusty. Apart from it being 'grammar' I think you did very well. 9/10 mate.
I get what you're saying about the war stories from the great unwashed...
... and "lo and behold"!
I didn't notice any problems with your grammar. Punctuation is great, 99% of spelling is good, great capitalisation, even have paragraphs. What's not to like?
You did a better job than most of the commenters I see. More than 9/10 from me.
I replaced the short cable from my portable Makita, and rewired it with 7 meters of 12 AWG which can easily handle 25amps. Compressor motor doesn't heat up anymore than it did with the short cable.
If he wanted to add a 5m 1mm sq extension, that would a minimal voltage drop, much less than the variability of the grid.
Few things to mention...
Firstly, pretty much everything you said was correct. The only exception was the typical failure mode. An under voltage failure on a single phase motor will typically be the capacitor failing rather than the windings.
The start cap has a rated duty cycle, when you under volt the motor the motor won't have the rated torque, which when presented to the load will cause it to run at a slower speed. In the instance when the motor still starts, it will generally take longer to do so, heating the cap up more than it was designed for and limiting its lifespan.
If you really under volt it, it wont spin over fast enough to trip the centrifugal switch, leaving the start cap connected until the breaker or thermal cutout trip, or the cap blows up.
The windings absolutely heat up as you said, but the cap will generally go first.
Most modern houses will run 16A breakers rather than 20. In either case though, the breaker doesnt trip at its rated current straight away. They have a curve. A little over, at say 20-25A, its rating could see it last hours before tripping.
Not a lawyer, I'm an electrician, however I believe it's the case that you can do electrical work on appliances etc that plug in. So DIY cable replacement and extension cords etc are ok. Not saying theyre a good idea, just that I believe you're allowed to do it. Don't take my word for it, check for yourself first.
The actual current drawn isnt as simple as converting hp to current either. For a 2.5hp compressor drawing 8A thats a marketing ploy. Yeah, its using 2.5hp worth of electricity, but its only doing 1hp worth of useful work, at most.
That asside, when starting the motor current is substantially higher. That 8A motor might be drawing 16A or more for that period. The voltage drop is based on that inrush current, not the 8A.
As for what to do about it, I'd suggest that the best solution is to go down to Bunnings (or whatever) and buy 2.5mm² 3 core orange circ and a couple of plugs and have your sparky do you up an extension cable. Unless your switchboard is quite a long way away, you wont have any issues with voltage drop and I'd suggest the warranty department wouldn't be able to tell.
Yes to this. In NSW at least , an electrician is licenced to work on/install ELECTRICAL INSTALLATIONS, An electrical installation stops at the GPO.light switches and sockets. The Gas and electricity act 2017 in NSW specifically states that devices that are plugged into a GPO are not part of an electrical installation. Think about the appliance repair man , or warranty work on your plug in gadgets. They are probably not being repaired by a licenced electrician ,but an electrical engineer or technician.If you dont feel confident in what you are doing re electrical repairs ,find someone who is. MAKE DOUBLE SURE THE THING YOU ARE WORKING ON IS NOT ENERGISED. discharge capacitors that are in circuit, they can hold charge for a long time.
When I wired my Garage [and got my sparky mate to check it and effect the connection to the bit I know not to touch] I put some old fashioned ceramic fuse wire [old federal fuse] types in the circuits as a tool safety as waiting for a breaker on the board to throw on an amp overload might damage a shorted out tool, paid off one day when I jammed a table saw and expected smoke from the motor following the terrifying growl signalling disaster. the low amp fuse blew and saved the day.
Maybe Kenny Bloody Wilson could sing 'Livin next door to Albo'?
Once you add 3 lengths of air hose, you can then jack the pressure cut off switch to 8 bar ( under the black plastic cover )
Then who gives a cr4p about power cords.
Really appreciate the explaining of relationship between voltage - amperage - horsepower. I have a 240v 6hp beast, and I parked it 5 feet from my breaker panel in the garage and ran the dedicated 240v 20a outlet so I can use the factory lead, which by the way, seems fairly thick and robust. The one aspect you didn't mention is volume and pressure drop if you use gimpy air hose over long distances. I have 3 20 foot hoses, and I only use as much as I need to reach where the work is. The other option is to run pipe and have outlets along the way so you can have full air delivery a fair distance from your compressor. As you said, an air nailer doesn't put much demand on air delivery, but if you are polishing a car with a polisher that eats 11SCFM at 75PSI you are definitely not going to want to have 15 or 20 feet on unneeded hose coiled about on the ground starving your tool of air. Great video, and I am not one of those who wishes to prove you wrong (like you said) - because you certainly are not - but just wanted to add that aspect. Thanks for another great lesson.