For those that have a "decent" understanding of domestic power design- this is clarifying- dare I say "enlightening". For most/all others (please listen: DIYers...) this can literally save lives. Thank you from those of us still walking the planet. PLEASE: if you are unsure or confused- call an electrician. It's much less expensive. Much. much less.
I have L1 and L2 with N so L1 has 120w but L2 doesn't have any electricity Do you happen to know if I can put a new breaker in the panel for the other (L2) I don't even know if I have L2 already in the panel Thanks
ahmad sherzai: L1 should have an rms voltage of 120VAC. L2 should have an rms voltage of 120VAC. L1 & L2 Voltages are 180 degrees out of phase at their peaks. The rms voltage across L1 & L2 should have a rms voltage of 240VAC. re: "Do you happen to know if I can put a new breaker in the panel for the other (L2) I don't even know if I have L2 already in the panel" No one on YT can accurately answer that ^^ question with any degree of confidence without examining your panel in detail.
A B....... the guy doesn't seem to even know how to identify the parts in his distribution panel, and you're hitting him with phase angle separation and RMS voltages..........LOL!!!
This is the best explanation I have found online. Seriously, out of hundreds of videos and forums, this is absolutely the best video. Thank you for being thorough with the visual and the explanation.
Not to get off topic but when I was just young and dumb taking a three basic electricity and electronic course in high school, my instructor spoke about dirty electricity. I did not fully understand it until I started working on Digital Imaging equipment, Copiers, Printers, Fax Machines and so forth. We had serviced this equipment in old home offices and old buildings. Sometimes having weird problems on equipment, anywhere from a paper jams, dirty copy and a whole bunch of strange problems, false error codes, etc.... The first things usually checked was the voltage hot to ground to see if there was any voltage present. In some cases 30-60 Volts. Hot to Neutral should be 120 and neutral to ground also 120V. The problem was either bad ground outside, or a problem in the panel / Case. It was unreal the strange problems you can have in electronics with a bad ground to hot. Hope this shed some light. Good Video.
Nice clear description. As a lectrician who became an engineer I used to draw simple diagrams for engineers with PE license about how the neutral carried no or little current if the load was balanced on a 3 or 4 wire system. I am retired and buying a stand by generator. I was looking here to see the 2 buses in the main panel, a ground bus and a neutral bus bonded together at the main panel only. Note: doing short circuit studies the max fault current for CB trip is along the path of the source circuit, so running the grond wire with the circuit is important. Learning ohms laws as a lectrician by heart, it helped me throughout my career analyzing problems. My specialty later became protective relaying and switch gear. Did my last project at age 80. Loved my work.
An older video but an excellent and explanation. You broke it down for everyone to understand. I reviewed this because I'm having trouble explaining to some newbies and all their hearing is "don't do it" as opposed to "why". Thanks.
Some clarifications: Neutral at the utility's (Power Company) distribution transformer is the center tap on the 240/120V transformer secondary. It's needed for the user to have 120V power and it does carry the imbalance current. Most utilitys ground neutral at the pole and most codes require the neutral to also be grounded at the service entrance of the building. If the neutral conductor between the transformer and the service entrance should break, you will probably get current flowing through the earth which can cause abnormal voltage fluctuations. The main reason a ground wire is run in all the premise circuits and connected to metallic enclosures is safety. If you have a hot wire insulation failure, you want a good, low-resistance path back to the source so that the breaker will trip. M. Perry, EE, PE Ret.,
Thank you for this video. In my younger days as an electrician (pre GFCI days) I didn't understand the point of a separate ground and neutral, since putting a voltage meter on the hot and neutral wires would produce the same reading as between the hot and ground. It's all about safety, and having been zapped a few times I can appreciate the concept.
Hey grayfurnaceman, I'm one of those people with a BSEE degree but only recently have I HAD to actually learn what we call Bonding (the connections of Neutral/ Grounds/ ground bars/ pipes/ enclosure boxes, etc). I also came to understand, after working 24 years as a EE mostly on electronic (DC) circuit design, the need for knowing that ground and neutral are NOT the same thing. I also had to trace wiring on a circuit diagram of the type you have drawn here, and talk my way multiple times through the reasoning. I also had to see the reasoning in my own way and then understand the explanation of neutral & Grounds connections by reading the NEC handbooks, but this time it was not Brute Force reading, but a more practical understanding of the kind you went through on the video. Thank you for putting this excellent explanation into a concise video.
It is indeed alarming how poorly many EEs and licensed electricians really understand "ground, " let alone everyone else. It leads to all sorts of unsafe design,maintenance practices, and installation, and tons of garbage documentation that confuses grounding issues with sloppy references to "ground". I try to instill in Electronic Engineering Tech students the importance of being clear on schematics and with terms. It is better to call anything that is NOT EARTH ground, and NOT AN EQUIPMENT GROUNDING CONDUCTOR a circuit reference, 0V, etc. If we could only stop engineers from calling everything "ground" when they mean "return path", circuit common point" or "reference point" in a circuit, and stop using the same generic "earth ground" symbol for everything! All "engineers" should have to study the electrical code and learn about actual machine installation in the real world. See Mike Holt's Videos.
Secondary of power pole transformer is center tapped, and that tap is the neutral point in the system, whether grounded or not. Center tap is connected to neutral bus in main box by third wire from pole. L1 and L2 are each 120 volts to neutral (center tap), but 240 volts between them, due to being on opposite ends of the secondary, therefore 180 degrees out of phase with each other. L1 connection in box supplies breaker loads with 120 volt current that returns from loads through white wires to neutral bus in main box, L2 does same, but 180 degrees out of phase with L1. When L1 and L2 neutral currents combine at the neutral bus in the main box, they cancel each other completely if they are equal at that moment (Kirchhoff's Current Law). Unbalanced current (difference between L1 and L2) flows from neutral point in main box, through neutral wire back to center tap of pole transformer secondary, not to ground. Current in the 240 volt loads are exactly equal in L1 and L2 (series circuit) as long as there are no shorts to ground or ground circuit through load or chassis. No neutral current flows in 240 volt loads because there is no neutral connection, only L1, L2, and ground. Absent faults, the ONLY current flowing from the main box neutral bus back to the center tap of the transformer is the difference current (unbalance) between L1 and L2 120 volt loads, with NO neutral current from 240 volt loads, and no current flowing through ground. Of course, all this leaves out switching transients and static discharges, which can affect fault protection devices.
Hope my post was not misleading. Neutral is earthed at the mains box, and neutral does frequently carry current in most all systems. With separate 120-volt loads on L1 and L2, a perfectly balanced load with no neutral current would be a momentary state of changing loads, in most cases. There is a lot more to utility distribution than I know about so far, particularly in bonding and actual amounts of earth current in different parts of the system. My background is in aircraft electrical systems, and I am still working out the similarities and differences with what info I can gather on line. No big surprises so far--3 phase is 3 phase, and center tapped xfrmrs all work the same. Ungrounded 3 phase loads and single-point grounded signal circuits are more common on aircraft than you might expect, as are sophisticated distribution fault detection and protection circuits.
Hopelessand Forlorn airplanes are a lot smaller than national electrical grids. Much like birds perched on power lines you don't have to worry about the earth ground on them much either.
I disagree. The same considerations apply. If you are distributing large amounts of power (I suspect the 787 operates with total loads of around half a MW), short circuits to ground are always possible in the absence of a totally floating system, and can have serious consequences. Even in a totally aluminum airframe, bonding between skins and from airframe to components is critical. Unbalanced currents return to generators through the airframe, and poor bonding or grounding would be as hazardous as the ground around a downed and live power wire in a utility system. Aircraft data and communication wires are usually balanced and frequently shielded with single point grounding on the shield. Sometimes double shielding is used with the inner shield grounded at one end, the outer shield grounded at both ends, and no continuity between the two shields. Even in a well-bonded aluminum airframe, low levels of stray voltage are common due to ground current through airframe resistance.
I'm 51and I've been doing electrical and electronic projects since I was ten, and that was the most succinct explanation of neutral vs ground I've heard. Now I can repeat and explain the concept to anyone with half a brain. Thanks
+Android World Earthing means it goes to a ground rod. Grounding is usually the chassis of a component that goes to a ground rod and the neutral in the panel. GFM
Per national code here in the USA the ground and neutral are "bonded" together at the main panel or wherever the first point of disconnect is. (meter with a main breaker or similar) Once you get beyond that point the ground is redundant for safety sake. IOW, any shorts have an alternative path, which is why code calls for separate ground and neutral wires from any sub-panel all the way back to that first point. Some local codes may ask for bonding at both the meter pan and the main (first) panel. Further, the neutral here in the USA / Canada goes to another ground rod out at the pole transformer. IOW, you have one (or two for new code) ground rods at the house plus another at the transformer location. Why? Because we have what is known as an unbalanced feed for most residential power. We use a double tap transformer at the pole and that supplies each leg with 120 volts. (240 volts across both legs) The other half of the power path for 120 volts is an earth ground, which code calls a neutral because it carries part of the load. The ground rods at the house are for safety in case something fails. The safety is always redundant so YOU (or your appliances) don't become part of an accidental circuit. (ouch!) Why so many ground rods? Considering how many variables are in the earth, sand, organic matter, moisture, lack of moisture, rock, gravel, etc. Not all of it conducts well so more rods at more locations mean a better chance for conducting electricity. Again, redundant for safety. (and reliability) In countries where they use only 240 volts (Europe, etc) they don't have a neutral and that's called a balanced main. Yes, they do have a ground wire for safety! (same as us) The reason they call it "balanced" is because you never have to worry about having too many items on one leg of a panel. With 240 volts everything is on both legs already. With an unbalanced system (pair of 120 volts and neutral) one most consider how much of the load is on each leg when planning a new system. BTW, if for some reason one of the load carrying wires has a bad connection usually the load fails to operate properly because the load causes the voltage to drop. A short circuit will only go to ground if a hot wire touches the chassis of the tool appliance... AND... nobody fooled with that 3rd prong. Of course a GFI outlet may trip if one of the load wires has a poor connection, but that might cloud the issue for this discussion. At any rate, all of this is beyond the wall outlet, which should be up to code. A shorted wire in a wall should go to neutral or ground, which will cause the breaker to trip. That's why metal conduit is always grounded, along with metal boxes. Oh, one flaw in the diagram on the video is the hot prong on an outlet is on the right side. If it's a polarized outlet (or extension cord) the smaller slot is hot and the wider slot is neutral.
I wonder how many have to point out this error in the diagram before GFM corrects it? I find the error mentioned by very few commenters. Let those who believe the receptacle polarity in the diagram take their VOM and check voltage from the ground opening at the bottom to the (usually wider) hole on the left. They will get close to zero voltage difference if not exactly zero volts and hopefully believe there is an error in the diagram. We will see how long it takes to get this simple but VERY dangerous error corrected in an otherwise excellent and valuable presentation.
rupe53 So there are many connections in a system where neutral is ground-bonded ( the pole and at every household main panel on the same transformer secondary)? Could that not cause extremely large neutral conductor current when the grounds are at different potential s? ( I can now only think of a wiring problem or a lightning strike to cause large ground differentials). I don't think my main panel has the neutral ground bonded, but to be honest I just went over to it now and decided that I was too tired to unscew the panel to look
@@mrlovemuscleable No, TN-C-S is the common in the UK. TT means that the ground is provided locally and has no connection to neutral. On TT RCSs/GFCIs are important as the breaker will not trip.
I was able to pull a permit in my city to do wiring in my garage as the homeowner. I learned that ground and neutral had to be isolated in the garage sub-panel but didn't really know why. This video was very helpful. Interestingly enough, this was the FIRST thing the inspector looked for and commented on. In the end I passed rough and final inspection. I will share this with my friends. Thank you!
Forgive me if I'm missing something obvious, but it still seems to me like "ground" and "neutral" would both carry current. I know they don't or else GFCIs would constantly trip! But since they're tied to the same potential in the main panel, and I'm assuming that the load connects its return (neutral) to its own chassis (earth ground), then the two wires between the load and the main panel are in parallel. Wires in parallel share current, so unless the impedance of the ground wire is really big relative to the neutral wire, then both wires would carry appreciable return current back to the main panel. What am I missing??
I guess there must be requirements for consumer electronics to isolate their return from chassis internal to their design huh? Everything would work fine as long as they do this. They'd probably want to do this anyway functionally, to control where currents are flowing.,
+Adeota 1 The neutral and ground wires aren't connected in parallel in this circuit. They are only connected at one point in the circuit, that is at the main panel...whereas if they were in parallel, they'd need to be connected at two points. Hence, the ground doesn't carry any current, unless a ground fault occurs and it comes in contact with either or both the hot and neutral conductors...in which case the gfci and/or overcurrent protection device will open the circuit (hopefully).
Agreed, I would also add that the diagram could be more clear if the neutral were shown between L1 and L2, with it grounded at the transformer. Show the transformer as center tapped. This will further solidify the concept that current must complete a circuit... it just doesn't get dumped in the ground....it goes somewhere in the ground, still (transformer).
If you follow the diagram above, the ground never completes a circuit. The current will follow the path to the utility pole to complete the circuit. Once the circuit breaker trips then the current will make its way through ground to the earth.
Something you don't make clear (perhaps because you don't know it?) is that at least one reason why you should not connect ground and neutral at the sub-panel is that current flowing from the load back to the transformer would then be *split* between the neutral and the ground wires between the sub-panel and the main panel (that split will be dependent upon the relative resistance of each path). This breaks a fundamental law of the ground connection: that is, it should not carry current under normal circumstances - only the neutral wire should carry that return current. I believe there are at least 2 issues with this video: - At 5:01, even if the ground and neutral connections are disconnected, it does *not* mean that "this entire box" is energized or at some high potential resulting in a shock, *unless* there is also a fault within that device, causing the live or neutral sides of the load to contact with the exterior metal (or other conductive) components of the device - i.e. regardless of the type of device this is, the exterior metal portions of it should not in any way be connected to the live or neutral wires (unless there actually is a fault in that device). - At 07:50 your description of the circuit flow is wrong. If the neutral wire failed between the sub-panel and the socket, as you describe, then *no current will flow*. The current can't simply jump from the neutral side of the load to the chassis as your mouse movements (at 08:14) suggest. In both of these cases your logic suggests that the neutral side of the load is connected to the chassis of the load - I would consider that a fault in the load device. While I appreciate that "grayfurnaceman" is trying to be helpful, I'm not sure what qualifications and formal training he has (his www.grayfurnaceman.com website suggests he has 35 years in the HVAC business, but no mention of formal training or qualifications), and it can be concerning when videos such as this are misinterpreted as professional advice - especially where safety is involved. No offence intended grayfurnaceman, but I would be very careful providing advice, involving safety, which may be wrong, incomplete, or open to misinterpretation.
Thanks for the thoughts. As you probably know, up until around 1995, 240 volt residential appliances that included 120 volt loads, used the chassis ground as the neutral for those loads. It was approved to energize the chassis ground under normal operation. Not quite a fundamental law. As for the circuit flow, you need to rewatch the video. If the neutral and the chassis ground are not separated, and the neutral has an open, the chassis will become a current carrying conductor. (I will admit the point at which the neutral opens determines whether or not the the current will flow which may be unclear in the video). If then, the chassis ground conductor fails open, (a most common incidence with loose fittings etc), the chassis will be hot because it is feeding thru the load. There is a video linked in this video that gives a further demonstration. As for my qualifications, I am a licensed electrician. I noticed that there was no easily understood videos on this subject so I provided one. No one video, article, or lecture will give a complete understanding of this or most other concepts. I taught on this and HVAC basics for 9 years and spent most of my time reexplaining in differing ways to get concepts across. GFM
Older appliances may not be double insulated with the full isolation of the chassis to neutral and hot, so that could present the issue of energizing the chassis as soon as it was turned on with a faulty neutral connection. That might be considered a fault in the device nowadays, but things weren't always designed with foolproof safety considerations.
There is a second reason. When you install a personal safety breaker (Don't know the name in US) that measures the load of L1 and N. So they are the same and no current goes to ground. You have to have that breaker in the main panel. And it wont work if N and ground are not separated out to the sub panels.
Robert Shrimpton well put together. I had the same safety concern too and the way he pointed out the neutral wires between the sub and the load. Obviously, there would be a fault and nonetheless, having a broken return conductor will not complete the circuit.
I CANNOT THANK YOU ENOUGH. I'm in high school taking hands-on lessons to be a home technology integration technician and I was killing my brain trying to figure the heck out why we have ground and tie N and G together in the breaker panel.
Thanks for the video! Around here each utility pole appears to have their neutral connected to a ground wire as well. Also, I do believe the illustration of an outlet in your diagram is a mirror reflection of what it actually is. You know, the "hot" is on the left side with the ground on the bottom. Best of luck and thanks for taking the time to save lives.
You are correct. The "system neutral" is indeed connected to the pole ground, usually #6 copper. The ground wire runs down each pole all the way to the base and then is typically arranged in a flat helix at the bottom, or "butt" of the pole as seen here ... i1.wp.com/www.iw5edi.com/wp-content/uploads/2013/09/pole5.jpg As a rule of thumb, a pole is buried for 10% of its length plus 2 feet, so the bottom of a ground wire on a 50 ft pole could be 7 ft deep. Ground wires are now having to be sheathed in some sort of conduit due to people actually cutting out lengths of it directly from the pole to sell for scrap. In one part of Texas several years ago, copper thieves figured out a way to actually cut down the primary neutral lines on old rural lines. Miles of copper wire disappeared over time.
Very well explained, cleared up a mystery for me (I'm a professor, a do-it-yourselfer, and the son of an electrician but it never made complete sense to me until now).
This does make sense...More so than others trying to explain the same thing...I use what I learn from your videos, to help me explain to others...Sometimes, I have had hard times being clear...You make it clear and you, have a gift for teaching....Lucky us, who watch you.
To me, everything this man does and says makes sense...Easiest to understand instruction and information out there...A very knowledgeable man and a great instructor....My thanks to the Grayfurnaceman once again.
Thx. You got me closer to understanding. Still fuzzy on why ground connected to neutral at the main panel doesn't complete a circuit and cause problems all of the time. Hopefully it will sink in sometime soon.
It might help you to understand that a neutral is used as a return for the 120 V or 277 V circuit or the imbalance to a circuit or box and that the ground is there for safety. In other words, a neutral will have a current on it but the ground should NEVER have a current. I realize that I am oversimplifying it but maybe this will help. P.S. I am a retired electric substation construction and maintenance guy and the most important part of the station was grounding.Hope this helps.
Thanks, guys. I guess I get lost in this as I think about AC and go wrong somewhere. To me, Hot and Neutral alternating between neg and pos polarities convinces me that the neutral is carrying current - 1/2 of the time - polarity / 1/2 of the time + polarity. So, in my mind, when neutral is +, and connected to a ground wire (-) at the box, that completes a circuit to me. As for path of least resistance, the bare copper ground is offering the least resistance, so… I'm missing something to simple to grasp, I guess. Appreciate the attempts to help.
Thanks for the video! The "debate" about the "separation" of the neutral and ground has been going on since the Mayflower landed! lol Anyway, as a physics major we look at these things a bit differently as does the Power Company. If you would be kind enough to next do a video about the "extra" ground for the computer power outlets it would be nice to view. Notice where the "extra/dedicated" ground is connected when it returns to the service entrance. Again, thanks for the video.
Ground is the path that the electrons take when a short circuit is created, the neutral is the path that the electrons take to return to it's source to complete the circuit.
Fault current returns to the supply on the neutral, not ground. Everything in this system is designed to provide a low impedance path back to the supply to complete the circuit.
@@MySpace662 I did read your comment. Current during a short circuit does not take the ground path. This is a large misconception in the electrical field. It takes the BONDING path back to the GROUNDED point where the neutral and GROUNDING conductor meet in the service box. This point is provided by either the manufacturer brass screw in the neutral bar that bonds the tub to previously mentioned conductors, or by a supplied bonding strap, or a separately sized bonding jumper. Either way, if fault went to ground, the impedance of the path back through the dirt via the grounding electrode, to the grounding electrode of the supply transformer would not be low enough to trip an overcurrent. Sorry for the long winded response but short circuit current does not go to ground.
@@schulerruler The ground wire offers an additional path for the electrical circuit to flow into the earth so as not to endanger anyone working with the electricity , in the event of a short circuit. Without a ground wire, your body could instead complete the ground path and may cause shock or electrocution.
@@MySpace662 please explain to me where the electrons go once they go into the actual ground. The fact is that without a complete circuit back to the supply, meaning neutral, there is no circuit. Meaning no potential across conductors, meaning the electrons will not move as there is no force imposed upon them. Ground helps us establish equal voltages as well as a larger plane for surges, but it is in NO way a low impedance path. There are many systems that do not even incorporate a connection to ground. Engineered designed approved installations. Look at the secondary on a transformer. If you do not give it a reference to ground, there is still Preciado across the coils, which still operates a load. In this case a contact between hot and ground won't do a thing. Line to line will pop a breaker, but a ground path is not required to trip it. It is the low impedance path established through BONDING that ensures this.
Thank you for this. I lost my dad to cancer last May. He was a master electrician, hell just short of an electrical engineer. I’m moving to his house and know I need to add a sub panel due to a remodel. I learned how to wire an electrical panel from him but he never covered a sub panel install. I’ve learned a lot from him and miss him dearly. Thank you for explaining this.
It would be good to show that every pole transformer is grounded to a ground rod and almost every house after about 1980 has it's ground connected to a waterpipe ground , which is about a hundred times better than a ground rod. Liked the video!
The drawing is not perfect but the discription is exactly how it should be. Not bad from somebody from a country where they shit on ground and neutral. Good job mate. Simple and clear explaination
Carolina Rodrigues Hi Where i come from the most important in the electrical installations is the grounding and taking care the neutral. I had some machines from the us and there was nothing done on neutral and grounding. Before we could start using them we most of the time had to rewire the machine so it could match the standards from my country. When i see the installations in the us many times the ground is used as neutral or visa versa. So my feeling is that in the us they not realy take care neutral and grounding. Where i live now in south east asia its even more worse. If you ask for a ground or a neutral they look verry strange at you. Ground and neutral are always combined. But that can give problems when you have one fase machines where you can turn around the power connector. Or try to buy a 5 pole power plug. 3 phase neutral ground. Or even a 5 wire power cable is hard to get. I hope i am clear in my explanation.
Carolina Rodrigues and btw this guy explains verry good the differents so you can see you cannot combune neutral and ground and you cannot use ground as neutral or neutral as ground.
+J IJzer If you saw an installation in the US where ground and neutral were being used as the same it was done by someone that shouldn't have been doing the wiring. NEC does not allow this and it is not common practice I can assure you. I've been a Journeyman wireman in the US for 30+ years and that is not how we train our people.
Tony Thomas ok i worked for GE in europe before and sometimes we got machines from the US and sorry to say they where bad wired but good to know that there are stil good rules for that. Be safe : )
Excellent video. Another reason for the earth ground is to pull the neutral from the power pole down to ground potential. There is capacitive reactance between the primary and secondary of the transformer on the pole. This couples voltage across to the secondary from the primary. If you didn't have the earth ground then the neutral in the house would be floating up at some voltage level above earth ground. As such touching the floating neutral or anything connected to it and say a water pipe at the same time could give someone a shock. This voltage potential shouldn't be confused with the magnetically coupled power coming from the primary and going to to L1 and L2 on the secondary. Instead it's a product of the capacitive coupling between the primary and the secondary of the transformer on the power pole.
So, Joe, I have the typical Ontario 3 wire and ground supply and am showing up to 40V between grounded equipment; furnace, boiler, sump pump, and the cement floor. I have several standard galvanized ground plates; garage, hydro pole, solar panel array and horse barn. Power is coming from somewhere!!!!!!!
The big question is where is all the "grounded" equipment actually grounded. If your barn has it's own separate sub-panel and it is grounded through a long piece of wire to somewhere else far away then that could be the problem. You might have to drive a metal rod into the dirt under the cement floor and "locally" ground the sub-panel to the rod. I posted a separate comment about this issue. It is different from the comment you replied to. I'd suggest you read the other comment.
Again Joe, I have read your other post too and what you say makes sense, I agree. My barn has it's own buried ground plate as well as the incoming supply ground from the pole. The concrete slab (26' X 36") has re-mesh which is also bonded to the ground plate. To add to the confusion my COMPETENT electrician is also baffled and suggests taking readings between house ground and various remote test grounds. The condition fluctuates depending on how much load is applied by my dairy farm neighbour a little over a quarter mile away! We have the same electrician who, by the way has many years of industrial experience too. JPP2672 confuses me!
I'm NOT an electrician, but I tend to agree with the comment that current doesn't only take the path of least resistance. It takes all possible paths, just at different rates. From comments I have read, if your neighbor's dairy farm has a loose or open neutral somewhere, then his current is going to travel back on his ground and energize the earth. Current could then travel up from earth via your ground rod and into your panel and then through your neutral while trying to find a way back to your power pole/transformer. The catch is, if he is 1/4 mile away, I think that would be very unlikely.
@ munsters2 - Correct. The ground is like a huge carbon resistor and as such it can be thought of as an infinite number of carbon resistors all running in parallel. Accordingly, you can apply voltage to it anywhere and draw current out of it anywhere else to complete a circuit. And as you have stated all the current won't necessarily flow in a straight line between the two points. You can also have additional current flowing along curved paths on each side of the line as well. Also remember that the water content in the soil and how densely the soil is packed affects the resistance. So even a quarter of a mile might be carrying a substantial amount of current.
When it comes to power transmission, there is no difference between the neutral and one of the hots in an American residential installation. The neutral wire does not "return" power any more or less than the hot wire does. The actual difference between a neutral and a hot is that the neutral is connected to earth through the main panel. That connection to earth gives it zero potential between itself and earth. That should not surpise anyone. What is surprising is how many people never made the transition in science class when they stopped talking about D.C., and started talking about A.C. The whole circuit from the generator at the power plant to your light bulb and back again are connected. The electrons shove each other (but each electron only moves a tiny, tiny, distance) all the way through those wires in a loop and they switch directions and move in the reverse direction. Back and forth, that's alternating current. The flow reverses because the generator uses slip rings and not a commutator, the flow reverses as the rotor turns through the magnetic field. The multiple transformers between the power plant and your house do not change the fact that electrons are shoved by the generator and that moves them at your house in a back and forth motion.
The Exploratorium in SF used to have an exhibit where you could sit and pedal a generator like a bicycle and then flip on connected incandescent lamps one at a time. Man, it got super hard to pedal as each light was switched on! Great way to get an intuitive understanding of "work" -- and how powerful electricity really is -- but also the "connection" between the generator and its loads.
@@okaro6595 Yes, each electron only moves a tiny distance, then it goes back. I just re-read my original post and see that it could be misunderstood in that detail, so I'll rewrite that portion. Thanks.
It is good to point out that the Neutral to ground point in the main panel is isolated from chassis ground!!! Great explanation and very concise. Thank you!!!
I work on the distribution lines, so we don't typically work in breaker panels. I've struggled to remember difference between neutral and ground, but when you clarified neutral is a load carrying conductor, and ground is just that (shortest path to earth) it simplified things.. I would imagine grounding onto a water-pipe would be great idea in the perfect world. However I have been on calls where plumbers have been shocked, or experienced balls of fire from disconnecting the ground. Typically due to a damaged neutral line on the house service. Electricity is invisible, and if you see the fire, it may be to late.. This video is very informative with my trouble shooting.. Thank You..
Good explanation - thank you! Perhaps a minor point but... at 8:00 you say "if this wire failed" and point to the neutral wire from subpanel to receptacle. I'm about 99.9% sure that you actually meant to point to the neutral from main panel to subpanel. Breaking the neutral after the subpanel wouldn't create the "neutral fished thru ground" scenario you are describing. Breaking it ahead of the sub would. Maybe an annotation needed?
The "Neutral" that is coming in from the pole is NOT a neutral. It is called the messenger cable. Utilities do NOT want neutrals. We send power. The neutral is formed by the homeowner, at the panel, by bonding the neutral and the ground together at the panel, and then to generally a cold water pipe..this is the primary ground. Ground rods have nothing to do with the primary service ground. The reason we don't "bond" a sub-panel i.e. neutral, ground is because we need for the un-balanced load to go to a designated location and stop.. I repeat stop. Otherwise you'll have a condition called a "ground loop". All bonding is to be preformed at the load center, hence 4 wire connection. Other than that you were dead on. Remember, don't disturb the electrons while they are working...you will not be forgiven.
JPP2672 .. Thank you. why would I not get voltage between black and white but I will between black and bare and on a nearby Outlet white and bare. can you give me any help at all
It sounds to me as though you might have an "open neutral." That is to say you don't hand a compete circuit for the GROUNDED conductor. Neutral. Neutral. a current carrying conductor that carries the UN-balanced load to ground.
In a typical 4 wire home setup, there are two hot wires having AC current but offset by 180°. Messenger cable (aka neutral) is bonded to earth ground. Does all the current that comes in from the hot wires exit the house via neutral? I can't envision all the power going into a copper pipe to enter the earth. It's a long way back to the power plant.
The neutral is kind of a gathering place for 120 volt circuits. When a load, say 10 amps, passes power thru, it goes to the neutral. If another 10 amp load is energized from the other hot line, the power passes from one hot thru the 2 loads to the other hot line with no power passing to the power pole thru neutral. If the the loads are unequal, say one is 10 amps and the other is 5 amps, 5 amps goes to the power pole thru neutral. I have more videos on grounding and bonding on my channel. Virtually no power passes thru the earth ground. Hope this helps. GFM
When I look at the plugs, I say "Wide White". The neutral wire goes to the wide slot. "Wide White" is what I get from high school foot ball where we were taught "Wide Right" meant the wide received on Right Side. This helps me remember. The ground connection is easy to remember. I also, use a black transparency pen to mark the hot on a new plug that I am installing. Ink from the pen comes off with plane water and no soap.
yes, good. I had a range in an old apartment using the ground as a neutral and if you touched it AND the faucet, LIGHTNING! The chassis was energized..Ive also had electricians in a fire repair (under my General contractor work) fail to wire this properly and the inspector passed it, but when I called and reported the issues he returned in flames and kicked asses! Good job. Important clarification. The meter will read the G and N to be in common but they are different in function! Thanks for the good work here!
What a great video, this normally confuses people because it is hard to rap your head around until it is explained very clearly. Main panel , sub-panel, whether to bond sub- panel is something very important that everyone dealing with this had to learn at some point. I'm sure you just helped a lot of people with your clear explanation and graphics!!
why can it be ok to bond neutral and ground in main panel, but not in sub-panel. When it uses the same power. In other words, whats the difference if you have a short in a main panel where ground and neutral are bonded vs a sub-panel where ground and neutral are not bonded, or why not wire the main panel like a sub-panel having the ground separate from the neutral or wire the sub-panel like the main panel by bonding the ground and neutral in sub-panel. I mean if the electric short will travel properly in main panel why won't it do the same in the sub-panel if it's bonded the same as the main power?
+gtmustangcobra We need the convenience of sub panels, but at the same time we realize they add risk. It is not a perfect world. So we don't want to push our luck beyond the main service panel as far as neutral bonding goes.
+gtmustangcobra LOL..My question also!! I have asked electricians' this same question and I got nothing but shrugs or.. 'just because' for an answer. I think it's got something to do with the uncertainties of sub-panels in terms of grounding and the higher risk of introducing potential (think ohms law...) of the neutral (grounded wire) and the grounding wire to ground.If you get a definitive answer, please let me know and vice-versa.... :)
+gtmustangcobra Neutral is only grounded at the very start, before passing through any circuit breakers (particularly leakage protection), usually at the step-down transformer. If neutral is grounded at consumers' side (sub-panel, etc.), then it will mainly result in nuisance tripping of leakage protection devices (if any), because neutral current is "leaking" to ground.
steve jones if your breakers tripped automatically you would very quickly become annoyed by that. Every time your air conditioner, or refrigerator cycled on you'd be resetting the breaker. Because loaded motors require surge current to start. But it is very difficult for simple mechanisms to differentiate between those allowable surges, and fault conditions.
Good point, and actually 0 Hz is DC. Once you go to 1 Hz or more it's AC. The main reason NOT to use that terminology is to avoid confusion because they behave so different. There was a time in the USA where utility power might have been DC (NYC started out that way) and since they were pioneered by different people with different schools of thought they didn't use the same terminology.
Thanks for the clarification. Now, how does changing the plug you illustrated to a GFCI plug change the wiring coming from the sub-panel?....Or does it? Well it would have to because the GFCI plug uses a solenoid switch to keep the circuit closed, & it doesn't use a ground. This is why you can upgrade a 2 prong plug to a GFCI. But also, we have to remember that the GFCI plug protects us (people) from Ground Faults by detecting a current imbalance of 5 milliamps. Where a regular circuit breaker trip if temperature reaches a certain point because of a direct short, or a short to ground situation, or a power surge (due to dirty power, lightning strike, etc) So a regular circuit breaker's design is geared toward protecting equipment for electrical damage from excess amperage; & to protect against electrical fire. But it does NOT protect people from over-current faults. This is why the GFCI circuit breaker & the GFCI plug is the best method of protection. You can replace an appliance, but you can't replace a person.
My brief stint as a maintenance electrician did not help me understand this completely. There are many discussions on forums as to Bonded Grounds, etc... Your diagram and explanation makes it clear for me -- 45 years later!! I have encountered stories as to how current, denied a neutral return, can travel along water pipes to other residences to reach a neutral-to-pole return. There is a lot more to say about the subject... Thanks much!
Great video! I've been working as an electrician for quite some time, and I miss several of our foreman why you only Bond the ground to the neutral in the main panel and I have not gone to clear concise answer such as you have shown in this video. Thank you very much, I greatly appreciate it! May Jesus greatly bless you!
Try putting a meter on L1 and another on L2. You will see how you are paying for the use of power that goes back into the system to go to the next meter. Why do you think you have to complete the circuit.
The neutral of the 240 phase winding that is center tapped carries the unbalanced load. Balance the loads on L1 and L2 and your meter will read the same. The power company is not stealing it from you. The next meter down the road on the same delta transformer is not sharing with your phase winding. It has its own.
True!! you send the power back to the electric pole indeed back to the electric company but is thru the neutral not the L1 or L2 legs. ruclips.net/video/cMzevUC4sao/видео.html This guy in this video is almost dead on but you dont send it back to the transformer to balance a load thats why there's L1 and L2 and also in South America theres only 2 wiring at the houses: the common wire and ground! That's it...I am not saying that is safe but even here in the States old house used to use the 2 wiring system back in the days....
Drink some water before speaking, all the smacking is gross. And mention the country which you are talking about, where i live there is only one panel in each house, and connecting the earth to neutral is not allowed here.
Thank you very much. I was trained for ten years in the service with DC circuits. We had very little almost non-existant training with AC circuits. You cleared up a lot in ten minutes that I had been struggling with for ten years. lol! Thanks again sir,
Being a master electrician for 10 plus years most of what this man is saying is not correct. He is trying but this information is misinformation. Do not do what is told to you here. The terminology is wrong and he is not an electrician. Its called the grounded conductor and the equipment grounding conductor. I didnt hear either of those terms mentioned. Maybe you should take an electrical class before you misinform 1.2 million people. Please go to school
Amen!! Grayfurnaceman IS a good man but should stick to his area of expertise which is HVAC. People should check this out : ruclips.net/video/mpgAVE4UwFw/видео.html
From what I'm now understanding ground doesn't really protect you,I watched Mike Holt videos and ground will carry a load because of the resistance of the soil,won't trip a breaker
Eric Van I had the same thing happen to me, someone tried to tell me that when incoming voltage drops current goes up and destroys equipment, they were thinking about how a transformer works, I explained ohms law of I = E over R, and I decided to move on myself after all the reteric
Tony66777 dude… are you serious? Everything he said is correct for anyone trying to understand how the system works….not for someone trying to wire a house. Don’t come in with this 10 year bullshit. Blah blah blah.
"Electric current, after passing into the earth travels to the diametrically opposite region of the same and rebounding from there, returns to its point of departure with virtually undiminished force. The outgoing and returning currents clash and form nodes and loops similar to those observable on a vibrating cord. To traverse the entire distance of about twenty-five thousand miles, equal to the circumference of the globe, the current requires a certain time interval, which I have approximately ascertained. In yielding this knowledge, nature has revealed one of its most precious secrets, of inestimable consequence to man. So astounding are the facts in this connection, that it would seem as though the Creator, himself, had electrically designed this planet just for the purpose of enabling us to achieve wonders which, before my discovery, could not have been conceived by the wildest imagination." Dr. Nikola Tesla
We have all marveled at what Dr Tesla discovered. However, he was never able to make his high frequency, ultra high voltage power system work. And how lucky we are that it did not. No electronic device we now use would operate with all the earth as a conductor. However, we would not need lights outside at night as the entire earth would glow. In any case, the voltages we are using in these panels are far too small to travel through ground effectively. Thanks for the comment. GFM
Pretty deep stuff from Tesla, which I'm sure is fascinating study, but as far as this video is concerned, it's more practical knowledge. Understanding the difference between neutral and ground, even though they are tied together in the main panel, and are at the same electrical potential, but are not tied together in a subpanel, can be a challenge to wrap your head around. The main thing to remember is that neutral is the return path, and ground is protection.
Hope you're not asleep when you stick your hand into a panel. Unfortunately this info doesn't work well as dog and pony show entertainment. Stay awake, don't die, pretty simple.
excellent resource, I found and resolved this issue in a house yesterday .found neutral bar in subpanel included bare ground wires, I screwed a separate bar to the subpanel box to isolate ground wires. also replaced breakers with new ones. + GFCI plug next to the sink
Say you want to add a couple rooms to your house or send electric to your garage you would install a sub panel there. Make sure your sub panel is actually designed to be used as a sub panel. You can use 12/3 for instance (depending on amps drawn and placement of wire, up on a pole or buried require different types) to the sub panel instead of 2 lengths of 12/2. 12/3 black is line one and red is line 2 so you can have 240v receptacles out of the sub panel and two separate circuits for receptacles and lights. The bare ground wire buss bar is not to touch or connect to the subpanel but rather connect to the service/main panel. The neutral/white goes the neutral buss bar and bonding screw (green screw) removed so that it does not connect to the sub panel either. Double check all codes and rely not on what I said here, code changes everywhere. Safety first and second then double check
***** Studies have proved that talking fast while teaching a subject keeps us alert and therefore improves comprehension; whereas speaking slow induces daydreaming, loss of focus, and reduces comprehension. Besides, for all you slow folks, its a youtube video. You could always play it over as many times as it takes to get the subject....duhhh!
Lawrence Ballack Studies have shown that people who find reasons to bitch about free well layed out and easily understood informational youtube videos are complete twats. This video helped me understand things that my teacher couldnt! Thanks man
I appreciated your video, and your explanation which sadly too many idiots can't seem to understand. No matter how much you try, or how much effort you give in order to explain something, you will never be able to educate the fools who think they already know more than anyone else. I was born and raised in the U.S. but have lived in the U.K. for 25 years, and although we only have 240 volt supply ie Live and Neutral instead of a center tapped transformer which would give 120V capability, the grounding principle is the same. I wish that our plugs weren’t so damned big and awkward! Keep up the good work!
This is the explanation I have wanted and needed for 45 years. I always had a rough idea about this, and that's all I needed for telecomm work. Thanks for the diagram AND the explanation.
I've watched this guys video's on several occasions and on several subjects...I have learned from every one of them....My thanks again to the gent that makes these. Vern
Nice video. One very important concept to take from this is the primary purpose of ground is to provide a low impedance path for fault current to flow so the breaker will turn the circuit off. That is pretty much its entire purpose - blow the breaker as quickly as possible.
That depends on if you mean earth ground or neutral. If you mean chassis ground to neutral in the panel, correct. If you mean earth that is not correct. Earth ground will not kick the breaker. I have a playlist on these issues: ruclips.net/p/PLItXrh64d2JNJOjSivaYXeX88i8MNWgwu One of the videos there is from Mike Holt about grounding myths. It is very good and explains it well. GFM
Too add to that, the ground wire also serves to short circuit your body so that little or no voltage appears across it before the breaker blows. So your body won't feel anything since the ground wire bypasses it providing a low impedance path for the fault current. So even if the breaker failed to blow, you would still be safe until the ground wire burned up.
Huge thanks for this video. I have a 2 year tech diploma in electrical engineering and power system electrician journeyman ticket plus 7 years in the field and I couldn't explain it that clearly
super important.....me and my buddy upgraded the service at my apartment building few years back....im a licensed contractor and he has his journeymans license....the only thing the inspector really checked was grounds and neutrals separated in subpanels...2 ground rods and water pipe..he was there 5 minutes tops..
I'd like to say thanks for taking the time to fully explain it. I've been in the field for 8 years and have a strong background already, and this just solidified it. Even a lot of electrician dont know why you dont bond subs or what a ground rod does. They just know the nec says so.
Ryan You are correct! NEC only tells you what you may or shall do. It does not tell you why. So, why are all the equipment grounds connected to the neutral in the main panel? Just want to make sure you understand that part. Respectfully, Kevin
@@KevinCoop1 in a nutshell, you want the ground and nuetral bonded to clear lightning strikes or line to line shorts on the utility side. In a sub you dont want them connected. If you were to lose a nuetral, it would use the egc as a current carrying conductor and put a potential on anything grounded. Including cases and exposed metal.
Ryan The question was why equipment grounds are bonded to neutral. In your comment, line to line and line to neutral faults have nothing to do with grounding. Also, grounding Electrode conductor is connected to the neutral to dissipate lightning. So, if you have a line it ground fault in a utilization equipment, you will have higher amps flowing on the equipment ground system. What is the path of the high amps or where do the travel to. This is very important to understand most of the Article 250.
I am not an electrician but was told that there are additional reasons why power generation stations and line stepdown transformers are grounded that do not involve lightning strike mitigation. It is still a head scratcher to me but it involves autobalancing of the two sides of 2 phase power. Supposedly if a residence used a large portion of their power from one phase while using little power from the other phase then some problems would result but for the grounding on the stepdown transformer. Anyone have any further info?
Think you for explaining this to a left hander. It makes it a lot easier to understanding with the diagram. I do believe I have a breaker box with the N. and Ground all together. It is a 40 year old box with circuit breakers. Your Audio is good and the camera was stable. Thanks!!
Thanks - I don't like messing with electricity (since getting a good shock @ 6yrs old..) but being a home owner means I sometimes have to. This clearly illustrated something I never understood .. and for teaching me this lesson I truly say THANK YOU.
Great video, One thing to explain however, there are many house built today that have the main disconnect at the meter. The example you gave indicated the main disconnect is in the "main panel". When you the main disconnect is at the meter, the load panel acts as a sub and the grounds and neutrals are separate at that location and not tied together. As a home inspector this is one of the main items we look for when we have a main disconnect at the meter, usually outside the house. One very important thing to remember, if you don't understand this issue, DO NOT OPEN your panel box. Call a licensed master electrician. This can Kill you if you touch the wrong wire or bus bar.
Very clear and through explanation. In some countries the ground is made at every pole so instead of using a earths ground in the house if lighting hits the pole it doesn´t make it inside the house at all. If the power company doesn´t ground every pole then if lighting hits the house and makes its way into the electrical system in your house it could blow things up.
Thank you very much for this explanation. Makes perfect sense to me. This comes at the right time. At some time I want to put in a sub panel. In the sub panel separate the ground and neutral. DO NOT tie them together. You just made life easier for a great many people. Thank you!
Thanks very much!! For more than 59 years; {Nor was it explained to me in college.} I could not figure this out on my own. Now I know! I Worked as a mill-write some years ago. I never knew why the panel was live with electricity, yet there was nothing shorting out.
Nice job it makes more sense. It can be summarized for memory by: the ground in the main breaker is for lightning strikes. And. Ground is not attached to neutral in sub panel incase neutral breaks causing a shock hazard at appliance case.
This video really help me to understand the whole concept of how neutral and ground works. Great explanation and very verbally clear on every single words. Thanks
Thank you for posting this simple to understand, and very informative video. Albert Einstein said; "If you can't explain it simply, you don't understand it well enough." I say; " If 'I' can understand you,... well, you possess a comprehensive understanding of it. ; )
This helped me greatly....we had to wire up panels in my HVAC class and I was like "what's up with the green jumper"? I use to do electrical work and always thought that the ground was separate completely from everything else and just went into the earth from the panel. When I saw it connected to the neutral I was almost certain my classmates wired it up wrong because the neutral carries the load back to complete the circuit; but if there's a surge then there has to be a place for it to go or it will burn up everything like you said. You're video's are a life saver.
Awesome explanation. Simple, slow, easy for me to understand. It answered questions I had. I have been doing it right for some time (I am not a electrician, but am in electronics and appliance repair). This answered many things I needed to know. Good job.
The reason we don't connect ground to neutral is because when current is flowing through it you will have a voltage above ground because wire has restance. It is possible to get shocked by touching the neutral wire if your far enough away from the main pannel and current is flowing through it. However in the 70s before this was added to the electric code they often grounded the sub a pannels using bonding clamps just like the main. Also 3 wires were allowed in all dyers and ovens. This was all changed but many old timers still do it that way. If your house is from the 70s it's likely your dryer is wired thus way without a extra ground wire.
You did a better job of explaining this than either the edison guy or my inspector. It's not terribly complicated but it takes some of us, and by that I mean me, more than once to get it. Good job and thanks for posting
I appreciate your attempt to explain the difference between ground and neutral in a panel. The NEC codes in the 300 chapter explains in detail what and where grounds are required and when they have to be separate such as sub-panels. One important thing that I think you left out is the fact that the ground has to be separate from the neutral in sub-panels so that, in the case of our fault, it will create a high current situation which will cause the breaker to trip there for protecting life if someone happens to touch it. Of course, in a normal situation the line would come in, power the load and then return to the source on the neutral.
Braeburn Hilliard's Channel The NEC tells you what you may or shall do. It does not tell you why. Can you tell me why the ground and neutral are connected together in the main panel? What happens in the main panel when the short to ground gets to that point? I'm hoping you know the answer. Respectfully, Kevin
@@KevinCoop1 yes. Main panels are grounded because it provides an alternate pathway for current to follow if there is a breakdown between the neutral and hot wires in the normal operation of the system.
Braeburn Hilliard's Channel Not really. Earth ground (Grounding Electrode Conductor) is for lightning and intended to "ground" neutral called "grounded conductor". That part of grounding is done. Equipment ground conductors are installed with feeders and branch circuits to cause a short circuit if metal parts not intended to be energized are energized. A high number of amps travel back to the main panel, onto the neutral, out to the utility transformer, through the transformer coil, back to main panel, to the branch circuit breaker(hopefully) and have enough amps to create a magnetic field strong enough to cause breaker to trip. If this makes sense to you and you start applying it to Article 250, it will make a lot more sense of why it says to do certain things. Respectfully, Kevin
@@KevinCoop1 yes, that's exactly what I mentioned in my very first comment. I thought you were asking about any additional reasons why main panel would require being grounded. That's the only other thing I knew. Of course, a lightning strike may cause failure of the install circuits in which the ground would provide a route for current to travel just like I mentioned. I kind of think we're saying the same thing.
Thank you for this excellent video. In most cases, however, the only place that the neutral and ground are joined is at the incoming power meter. There should be one or more ground rods at the meter pedestal. The ground (green) and neutral (white) should not be joined anywhere inside the house. It depends on your definition of "main panel". The main panel and first breaker on any recent electrical services is at the meter. Your video is an excellent illustration of why there is a "stray voltage" problem at many dairy farms where the neutral and green are routinely connected at various panels around the farm. In too many cases, one old motor or pump wears out, shorting some current to the housing, etc and this sends current back through the ground, giving the cows a shock every time they try to take a drink of water. Cows then drink less water, give less milk and the dairy farm goes out of business. Neutral (usually white) and green wires should not be joined anywhere except the power meter. Each panel should have its own ground rod and separate ground bar inside each panel for the green ground wires. This is now code in many areas.
Thanks for the video. Informative. I'd also add that another reason for NOT bonding neutral and ground at sub-panels is due to the different cable gauge size between ground and neutral/power. If there was a problem and ground had to be substituted for neutral, generally ground is a smaller(high numbered) gauge cable relative to the installed neutral cable. For example, in a 30 amp scenario, the 10 gauge neutral cable, if lost, and electrically replaced by a 'standard' smaller size ground cable, the substituted ground cable could not handle the current/amps and could heat/burn in a situation where for whatever reason the neutral cable is lost. Basically ground wires are not designed to carry all the larger currents/amps in residential/commercial set-up.
Excellent video. I would like to emphasize that the ground in the main box goes to a rod or metal pipe that is actually buried in the ground. The chassis ground is just a symbol to indicate that the incoming ground wire is connected to it. It does not otherwise go anywhere. The main goal is that the ground wire does not conduct current under normal use. If there is only one connection between ground and neutral in the main box, this will be done. So two different grounded items will have the same zero volts between them and you would not get shocked when touching both at the same time.
heres my take away- sub panels separate ground bar bonded to box. this makes me crazy now cause on current job added 6 lines to a 60's or 70's sub panel where nuets and grounds share same bar well there is a water pipe near ill see if its good. hope no one repaired something with pex or some interrupter. great video!!! like you said it was always rolling around in my mind.
Its not the end of all times if neutrals and earth ground are connected. Consider the dryers and stoves connected with 3 wire that used the ground as neutral. Not the best way but done forever. Its just better to separate. GFM
You are correct in your explanation of why the neutral line is not also used as a ground but further explanation is needed. In order for the chassis to be hot two things need to happen one the neutral wire has to be open, which in this scenario is also the ground and secondly the hot side be shorted to the chassis correct?
David Heins Why would the neutral need to be open? If the hot gets pinched while putting the metal cover or case back on, and everything else is still connected, it is a short circuit with most of the current going through the case to the equipment ground. Less resistance than the load. Respectfully, Kevin
Excellent !!! What I don't understand is that ground line connection returning back from the sub panel to the main panel. We don't have that configuration in our house. We have just a ground bar in the sub panel gathering the house ground wires together and from there there is a thick ground cable going to the earth of the backward. Is it ok with this ? Thanks
Gray I worked for a electric utility as a contractor and one of the first things the utility told us in are orientation was do not assume that the coating on overhead wires is insulation some coatings are just weather proofing and do not offer much if any protection
If you are using cable (as you would when wiring a house) the conductors will be insulated, except the ground. Two conductor cable has a black (line) and a white (neutral), plus ground. Three conductor cable has black (L1), red (L2), and white (neutral), plus ground.
I'm new at all of this. It would be helpful if you could explain the part that the L2 wire (leading to the main panel) plays in all of this, since power flowing to the load is traveling through the L1 and the neutral. Thanks.
Isaac, What might help to clarify is that typically, both L1 and L2 would be run to a true sub-panel, not just the one drawn in the video. L1 and L2 are legs of the split phase system. They are your 'hots.' They have 120V with respect to neutral, and 240 volts with respect to each other. If you didn't run both, you could not utilize 240 volts and you could not balance your loads running through the sub panel.
I asked this question to our experienced handyman if our homes are protected against lightening, & the answer was no. Today I learned u our homes have a jumper from the neutral to the ground. Thank you so much for explaining how it works so clearly, other it would have remained mystery. Do we get 3 phase power supply in homes & why, either way? Thanks
Thanks for the explanation of neutral and ground. It is so easy to understand too just not obvious. The images helped a lot to understand connectivity of the circuits.
Thank you your explanation makes clear sense. Wondering if you could do one on grounding and earthing of an ac subpanel and solar concentrator dc panel that includes an ac inverter. I believe two ground rods are in play there at the subpanel and cannot be more than 6 feet apart.
For those that have a "decent" understanding of domestic power design- this is clarifying- dare I say "enlightening". For most/all others (please listen: DIYers...) this can literally save lives. Thank you from those of us still walking the planet. PLEASE: if you are unsure or confused- call an electrician. It's much less expensive. Much. much less.
Thanks for the support.
GFM
I have L1 and L2 with N so L1 has 120w but L2 doesn't have any electricity
Do you happen to know if I can put a new breaker in the panel for the other (L2) I don't even know if I have L2 already in the panel
Thanks
I think you need an electrician.
GFM
ahmad sherzai:
L1 should have an rms voltage of 120VAC. L2 should have an rms voltage of 120VAC. L1 & L2 Voltages are 180 degrees out of phase at their peaks.
The rms voltage across L1 & L2 should have a rms voltage of 240VAC.
re: "Do you happen to know if I can put a new breaker in the panel for the other (L2) I don't even know if I have L2 already in the panel"
No one on YT can accurately answer that ^^ question with any degree of confidence without examining your panel in detail.
A B....... the guy doesn't seem to even know how to identify the parts in his distribution panel, and you're hitting him with phase angle separation and RMS voltages..........LOL!!!
This is the best explanation I have found online. Seriously, out of hundreds of videos and forums, this is absolutely the best video. Thank you for being thorough with the visual and the explanation.
Best explanation of the neutral, hot and ground I have ever seen.
Welcome
GFM
+roomba AGREED
Not to get off topic but when I was just young and dumb taking a three basic electricity and electronic course in high school, my instructor spoke about dirty electricity. I did not fully understand it until I started working on Digital Imaging equipment, Copiers, Printers, Fax Machines and so forth. We had serviced this equipment in old home offices and old buildings. Sometimes having weird problems on equipment, anywhere from a paper jams, dirty copy and a whole bunch of strange problems, false error codes, etc.... The first things usually checked was the voltage hot to ground to see if there was any voltage present. In some cases 30-60 Volts. Hot to Neutral should be 120 and neutral to ground also 120V. The problem was either bad ground outside, or a problem in the panel / Case. It was unreal the strange problems you can have in electronics with a bad ground to hot. Hope this shed some light. Good Video.
"Hot to Neutral should be 120 and neutral to ground also 120V. "
Did you mean to say hot to ground also 120V?
Nice clear description. As a lectrician who became an engineer I used to draw simple diagrams for engineers with PE license about how the neutral carried no or little current if the load was balanced on a 3 or 4 wire system. I am retired and buying a stand by generator. I was looking here to see the 2 buses in the main panel, a ground bus and a neutral bus bonded together at the main panel only. Note: doing short circuit studies the max fault current for CB trip is along the path of the source circuit, so running the grond wire with the circuit is important. Learning ohms laws as a lectrician by heart, it helped me throughout my career analyzing problems. My specialty later became protective relaying and switch gear. Did my last project at age 80. Loved my work.
An older video but an excellent and explanation. You broke it down for everyone to understand. I reviewed this because I'm having trouble explaining to some newbies and all their hearing is "don't do it" as opposed to "why". Thanks.
I don't know how many electricians that simply follow the code without knowing why.
GFM
Some clarifications: Neutral at the utility's (Power Company) distribution transformer is the center tap on the 240/120V transformer secondary. It's needed for the user to have 120V power and it does carry the imbalance current. Most utilitys ground neutral at the pole and most codes require the neutral to also be grounded at the service entrance of the building. If the neutral conductor between the transformer and the service entrance should break, you will probably get current flowing through the earth which can cause abnormal voltage fluctuations. The main reason a ground wire is run in all the premise circuits and connected to metallic enclosures is safety. If you have a hot wire insulation failure, you want a good, low-resistance path back to the source so that the breaker will trip. M. Perry, EE, PE Ret.,
Very clear video explanation of the circuits and ground requirements. The sub panel explanation was well done! Thank you!!
Thanks for the support.
GFM
Play at 1.5 speed, you'll thank me :)
Jason Johns yoooo so much better thanks!
thank you
Ha! It sounds normal.
Make sure you are able to listen and comprehend at that speed. Just saying.
👍
Absolutely best explanation on a ground vs. Neutral in a sub panel. I can't tell you how many homeowners wire the sub-panel incorrectly.
Thanks for the support.
GFM
Thank you for this video. In my younger days as an electrician (pre GFCI days) I didn't understand the point of a separate ground and neutral, since putting a voltage meter on the hot and neutral wires would produce the same reading as between the hot and ground. It's all about safety, and having been zapped a few times I can appreciate the concept.
Hey grayfurnaceman, I'm one of those people with a BSEE degree but only recently have I HAD to actually learn what we call Bonding (the connections of Neutral/ Grounds/ ground bars/ pipes/ enclosure boxes, etc). I also came to understand, after working 24 years as a EE mostly on electronic (DC) circuit design, the need for knowing that ground and neutral are NOT the same thing. I also had to trace wiring on a circuit diagram of the type you have drawn here, and talk my way multiple times through the reasoning. I also had to see the reasoning in my own way and then understand the explanation of neutral & Grounds connections by reading the NEC handbooks, but this time it was not Brute Force reading, but a more practical understanding of the kind you went through on the video. Thank you for putting this excellent explanation into a concise video.
Yes...but TMI. You lost most of the audience at the fire station...
It is indeed alarming how poorly many EEs and licensed electricians really understand "ground, " let alone everyone else. It leads to all sorts of unsafe design,maintenance practices, and installation, and tons of garbage documentation that confuses grounding issues with sloppy references to "ground". I try to instill in Electronic Engineering Tech students the importance of being clear on schematics and with terms. It is better to call anything that is NOT EARTH ground, and NOT AN EQUIPMENT GROUNDING CONDUCTOR a circuit reference, 0V, etc. If we could only stop engineers from calling everything "ground" when they mean "return path", circuit common point" or "reference point" in a circuit, and stop using the same generic "earth ground" symbol for everything! All "engineers" should have to study the electrical code and learn about actual machine installation in the real world. See Mike Holt's Videos.
Secondary of power pole transformer is center tapped, and that tap is the neutral point in the system, whether grounded or not. Center tap is connected to neutral bus in main box by third wire from pole. L1 and L2 are each 120 volts to neutral (center tap), but 240 volts between them, due to being on opposite ends of the secondary, therefore 180 degrees out of phase with each other. L1 connection in box supplies breaker loads with 120 volt current that returns from loads through white wires to neutral bus in main box, L2 does same, but 180 degrees out of phase with L1. When L1 and L2 neutral currents combine at the neutral bus in the main box, they cancel each other completely if they are equal at that moment (Kirchhoff's Current Law). Unbalanced current (difference between L1 and L2) flows from neutral point in main box, through neutral wire back to center tap of pole transformer secondary, not to ground. Current in the 240 volt loads are exactly equal in L1 and L2 (series circuit) as long as there are no shorts to ground or ground circuit through load or chassis. No neutral current flows in 240 volt loads because there is no neutral connection, only L1, L2, and ground. Absent faults, the ONLY current flowing from the main box neutral bus back to the center tap of the transformer is the difference current (unbalance) between L1 and L2 120 volt loads, with NO neutral current from 240 volt loads, and no current flowing through ground. Of course, all this leaves out switching transients and static discharges, which can affect fault protection devices.
+Hopelessand Forlorn but what potential is neutral at if it is not earth bonded? With all of those miles of transmission cables to build up a charge.
Hope my post was not misleading. Neutral is earthed at the mains box, and neutral does frequently carry current in most all systems. With separate 120-volt loads on L1 and L2, a perfectly balanced load with no neutral current would be a momentary state of changing loads, in most cases. There is a lot more to utility distribution than I know about so far, particularly in bonding and actual amounts of earth current in different parts of the system. My background is in aircraft electrical systems, and I am still working out the similarities and differences with what info I can gather on line. No big surprises so far--3 phase is 3 phase, and center tapped xfrmrs all work the same. Ungrounded 3 phase loads and single-point grounded signal circuits are more common on aircraft than you might expect, as are sophisticated distribution fault detection and protection circuits.
Hopelessand Forlorn
airplanes are a lot smaller than national electrical grids. Much like birds perched on power lines you don't have to worry about the earth ground on them much either.
I disagree. The same considerations apply. If you are distributing large amounts of power (I suspect the 787 operates with total loads of around half a MW), short circuits to ground are always possible in the absence of a totally floating system, and can have serious consequences. Even in a totally aluminum airframe, bonding between skins and from airframe to components is critical. Unbalanced currents return to generators through the airframe, and poor bonding or grounding would be as hazardous as the ground around a downed and live power wire in a utility system. Aircraft data and communication wires are usually balanced and frequently shielded with single point grounding on the shield. Sometimes double shielding is used with the inner shield grounded at one end, the outer shield grounded at both ends, and no continuity between the two shields. Even in a well-bonded aluminum airframe, low levels of stray voltage are common due to ground current through airframe resistance.
Hopelessand Forlorn
while the same considerations may apply the scales are completely different.
This is my second time watching this and I understand it so much more than the first time!
You sir are spot on. If you're not a teacher I think you should be. Super easy to understand.
I'm 51and I've been doing electrical and electronic projects since I was ten, and that was the most succinct explanation of neutral vs ground I've heard. Now I can repeat and explain the concept to anyone with half a brain. Thanks
Neutral carries current, ground doesn't except if there is a fault. Neutral is a system ground, the green wire is a safety wire.
+Bri G. Quite accurate. Thanks for the thoughts.
GFM
What about the main difference B/w Grounding and Earthing????
+Android World Earthing means it goes to a ground rod. Grounding is usually the chassis of a component that goes to a ground rod and the neutral in the panel.
GFM
grayfurnaceman ;, will n
Bri G. my fluke meter agrees with this statement.
Per national code here in the USA the ground and neutral are "bonded" together at the main panel or wherever the first point of disconnect is. (meter with a main breaker or similar) Once you get beyond that point the ground is redundant for safety sake. IOW, any shorts have an alternative path, which is why code calls for separate ground and neutral wires from any sub-panel all the way back to that first point. Some local codes may ask for bonding at both the meter pan and the main (first) panel.
Further, the neutral here in the USA / Canada goes to another ground rod out at the pole transformer. IOW, you have one (or two for new code) ground rods at the house plus another at the transformer location. Why? Because we have what is known as an unbalanced feed for most residential power. We use a double tap transformer at the pole and that supplies each leg with 120 volts. (240 volts across both legs) The other half of the power path for 120 volts is an earth ground, which code calls a neutral because it carries part of the load. The ground rods at the house are for safety in case something fails. The safety is always redundant so YOU (or your appliances) don't become part of an accidental circuit. (ouch!)
Why so many ground rods? Considering how many variables are in the earth, sand, organic matter, moisture, lack of moisture, rock, gravel, etc. Not all of it conducts well so more rods at more locations mean a better chance for conducting electricity. Again, redundant for safety. (and reliability)
In countries where they use only 240 volts (Europe, etc) they don't have a neutral and that's called a balanced main. Yes, they do have a ground wire for safety! (same as us) The reason they call it "balanced" is because you never have to worry about having too many items on one leg of a panel. With 240 volts everything is on both legs already. With an unbalanced system (pair of 120 volts and neutral) one most consider how much of the load is on each leg when planning a new system.
BTW, if for some reason one of the load carrying wires has a bad connection usually the load fails to operate properly because the load causes the voltage to drop. A short circuit will only go to ground if a hot wire touches the chassis of the tool appliance... AND... nobody fooled with that 3rd prong. Of course a GFI outlet may trip if one of the load wires has a poor connection, but that might cloud the issue for this discussion. At any rate, all of this is beyond the wall outlet, which should be up to code. A shorted wire in a wall should go to neutral or ground, which will cause the breaker to trip. That's why metal conduit is always grounded, along with metal boxes.
Oh, one flaw in the diagram on the video is the hot prong on an outlet is on the right side. If it's a polarized outlet (or extension cord) the smaller slot is hot and the wider slot is neutral.
I wonder how many have to point out this error in the diagram before GFM corrects it? I find the error mentioned by very few commenters. Let those who believe the receptacle polarity in the diagram take their VOM and check voltage from the ground opening at the bottom to the (usually wider) hole on the left. They will get close to zero voltage difference if not exactly zero volts and hopefully believe there is an error in the diagram. We will see how long it takes to get this simple but VERY dangerous error corrected in an otherwise excellent and valuable presentation.
rupe53 So there are many connections in a system where neutral is ground-bonded ( the pole and at every household main panel on the same transformer secondary)? Could that not cause extremely large neutral conductor current when the grounds are at different potential s? ( I can now only think of a wiring problem or a lightning strike to cause large ground differentials). I don't think my main panel has the neutral ground bonded, but to be honest I just went over to it now and decided that I was too tired to unscew the panel to look
In the UK and other commonwealth countries, we follow a type of earthing system called the TT system. We do have neutral conductors, split phase
rupe53 Wow! A whole lot of writing that has numerous mis conceptions on how electricity works. I hope you have learned differently in two years!
@@mrlovemuscleable No, TN-C-S is the common in the UK. TT means that the ground is provided locally and has no connection to neutral. On TT RCSs/GFCIs are important as the breaker will not trip.
I was able to pull a permit in my city to do wiring in my garage as the homeowner. I learned that ground and neutral had to be isolated in the garage sub-panel but didn't really know why. This video was very helpful. Interestingly enough, this was the FIRST thing the inspector looked for and commented on. In the end I passed rough and final inspection. I will share this with my friends. Thank you!
Welcome
GFM
I have 34 years experience and this is the best explanation I ever heard. Thank you.
Thanks for the support.
GFM
Forgive me if I'm missing something obvious, but it still seems to me like "ground" and "neutral" would both carry current. I know they don't or else GFCIs would constantly trip! But since they're tied to the same potential in the main panel, and I'm assuming that the load connects its return (neutral) to its own chassis (earth ground), then the two wires between the load and the main panel are in parallel. Wires in parallel share current, so unless the impedance of the ground wire is really big relative to the neutral wire, then both wires would carry appreciable return current back to the main panel. What am I missing??
I guess there must be requirements for consumer electronics to isolate their return from chassis internal to their design huh? Everything would work fine as long as they do this. They'd probably want to do this anyway functionally, to control where currents are flowing.,
+Adeota 1 The neutral and ground wires aren't connected in parallel in this circuit. They are only connected at one point in the circuit, that is at the main panel...whereas if they were in parallel, they'd need to be connected at two points. Hence, the ground doesn't carry any current, unless a ground fault occurs and it comes in contact with either or both the hot and neutral conductors...in which case the gfci and/or overcurrent protection device will open the circuit (hopefully).
Agreed, I would also add that the diagram could be more clear if the neutral were shown between L1 and L2, with it grounded at the transformer. Show the transformer as center tapped. This will further solidify the concept that current must complete a circuit... it just doesn't get dumped in the ground....it goes somewhere in the ground, still (transformer).
That's true only if the load isolates its neutral from chassis internally, as I stated above. Otherwise, the two are indeed in parallel.
If you follow the diagram above, the ground never completes a circuit. The current will follow the path to the utility pole to complete the circuit. Once the circuit breaker trips then the current will make its way through ground to the earth.
Something you don't make clear (perhaps because you don't know it?) is that at least one reason why you should not connect ground and neutral at the sub-panel is that current flowing from the load back to the transformer would then be *split* between the neutral and the ground wires between the sub-panel and the main panel (that split will be dependent upon the relative resistance of each path). This breaks a fundamental law of the ground connection: that is, it should not carry current under normal circumstances - only the neutral wire should carry that return current.
I believe there are at least 2 issues with this video:
- At 5:01, even if the ground and neutral connections are disconnected, it does *not* mean that "this entire box" is energized or at some high potential resulting in a shock, *unless* there is also a fault within that device, causing the live or neutral sides of the load to contact with the exterior metal (or other conductive) components of the device - i.e. regardless of the type of device this is, the exterior metal portions of it should not in any way be connected to the live or neutral wires (unless there actually is a fault in that device).
- At 07:50 your description of the circuit flow is wrong. If the neutral wire failed between the sub-panel and the socket, as you describe, then *no current will flow*. The current can't simply jump from the neutral side of the load to the chassis as your mouse movements (at 08:14) suggest.
In both of these cases your logic suggests that the neutral side of the load is connected to the chassis of the load - I would consider that a fault in the load device.
While I appreciate that "grayfurnaceman" is trying to be helpful, I'm not sure what qualifications and formal training he has (his www.grayfurnaceman.com website suggests he has 35 years in the HVAC business, but no mention of formal training or qualifications), and it can be concerning when videos such as this are misinterpreted as professional advice - especially where safety is involved.
No offence intended grayfurnaceman, but I would be very careful providing advice, involving safety, which may be wrong, incomplete, or open to misinterpretation.
Thanks for the thoughts. As you probably know, up until around 1995, 240 volt residential appliances that included 120 volt loads, used the chassis ground as the neutral for those loads. It was approved to energize the chassis ground under normal operation. Not quite a fundamental law. As for the circuit flow, you need to rewatch the video. If the neutral and the chassis ground are not separated, and the neutral has an open, the chassis will become a current carrying conductor. (I will admit the point at which the neutral opens determines whether or not the the current will flow which may be unclear in the video). If then, the chassis ground conductor fails open, (a most common incidence with loose fittings etc), the chassis will be hot because it is feeding thru the load. There is a video linked in this video that gives a further demonstration.
As for my qualifications, I am a licensed electrician. I noticed that there was no easily understood videos on this subject so I provided one. No one video, article, or lecture will give a complete understanding of this or most other concepts. I taught on this and HVAC basics for 9 years and spent most of my time reexplaining in differing ways to get concepts across.
GFM
Older appliances may not be double insulated with the full isolation of the chassis to neutral and hot, so that could present the issue of energizing the chassis as soon as it was turned on with a faulty neutral connection. That might be considered a fault in the device nowadays, but things weren't always designed with foolproof safety considerations.
There is a second reason. When you install a personal safety breaker (Don't know the name in US) that measures the load of L1 and N. So they are the same and no current goes to ground. You have to have that breaker in the main panel. And it wont work if N and ground are not separated out to the sub panels.
Robert Shrimpton well put together. I had the same safety concern too and the way he pointed out the neutral wires between the sub and the load. Obviously, there would be a fault and nonetheless, having a broken return conductor will not complete the circuit.
Robert Shrimpton p
good video and explanation
Thanks
GFM
What the hell u doing here . Its Thursday October 15
I CANNOT THANK YOU ENOUGH. I'm in high school taking hands-on lessons to be a home technology integration technician and I was killing my brain trying to figure the heck out why we have ground and tie N and G together in the breaker panel.
Thanks for the video! Around here each utility pole appears to have their neutral connected to a ground wire as well. Also, I do believe the illustration of an outlet in your diagram is a mirror reflection of what it actually is. You know, the "hot" is on the left side with the ground on the bottom. Best of luck and thanks for taking the time to save lives.
You are correct. The "system neutral" is indeed connected to the pole ground, usually #6 copper. The ground wire runs down each pole all the way to the base and then is typically arranged in a flat helix at the bottom, or "butt" of the pole as seen here ...
i1.wp.com/www.iw5edi.com/wp-content/uploads/2013/09/pole5.jpg
As a rule of thumb, a pole is buried for 10% of its length plus 2 feet, so the bottom of a ground wire on a 50 ft pole could be 7 ft deep.
Ground wires are now having to be sheathed in some sort of conduit due to people actually cutting out lengths of it directly from the pole to sell for scrap. In one part of Texas several years ago, copper thieves figured out a way to actually cut down the primary neutral lines on old rural lines. Miles of copper wire disappeared over time.
Thats why we install an EARTH LEAKAGE protection , circuit breaker .
it will trip when Ground/Earth makes contact with Neutral (Max 0,3 A)
Very well explained, cleared up a mystery for me (I'm a professor, a do-it-yourselfer, and the son of an electrician but it never made complete sense to me until now).
I'm glad you posted this video... wow... thanks
This does make sense...More so than others trying to explain the same thing...I use what I learn from your videos, to help me explain to others...Sometimes, I have had hard times being clear...You make it clear and you, have a gift for teaching....Lucky us, who watch you.
Glad I could help.
GFM
To me, everything this man does and says makes sense...Easiest to understand instruction and information out there...A very knowledgeable man and a great instructor....My thanks to the Grayfurnaceman once again.
Thx. You got me closer to understanding. Still fuzzy on why ground connected to neutral at the main panel doesn't complete a circuit and cause problems all of the time. Hopefully it will sink in sometime soon.
Surging Circuits l
+Mike Schmidle -- ???
Path of least resistance theory.
It might help you to understand that a neutral is used as a return for the 120 V or 277 V circuit or the imbalance to a circuit or box and that the ground is there for safety. In other words, a neutral will have a current on it but the ground should NEVER have a current. I realize that I am oversimplifying it but maybe this will help. P.S. I am a retired electric substation construction and maintenance guy and the most important part of the station was grounding.Hope this helps.
Thanks, guys. I guess I get lost in this as I think about AC and go wrong somewhere. To me, Hot and Neutral alternating between neg and pos polarities convinces me that the neutral is carrying current - 1/2 of the time - polarity / 1/2 of the time + polarity. So, in my mind, when neutral is +, and connected to a ground wire (-) at the box, that completes a circuit to me. As for path of least resistance, the bare copper ground is offering the least resistance, so… I'm missing something to simple to grasp, I guess. Appreciate the attempts to help.
Thanks for the video! The "debate" about the "separation" of the neutral and ground has been going on since the Mayflower landed! lol Anyway, as a physics major we look at these things a bit differently as does the Power Company. If you would be kind enough to next do a video about the "extra" ground for the computer power outlets it would be nice to view. Notice where the "extra/dedicated" ground is connected when it returns to the service entrance. Again, thanks for the video.
I think you are referring to what is called an Isolated Ground. The same feature is found on a lot of hospital equipment.
Ground is the path that the electrons take when a short circuit is created,
the neutral is the path that the electrons take to return to it's source to complete the circuit.
Fault current returns to the supply on the neutral, not ground. Everything in this system is designed to provide a low impedance path back to the supply to complete the circuit.
@@schulerruler I don't think you read my comment properly, I said when there is a short circuit.
@@MySpace662 I did read your comment. Current during a short circuit does not take the ground path. This is a large misconception in the electrical field. It takes the BONDING path back to the GROUNDED point where the neutral and GROUNDING conductor meet in the service box. This point is provided by either the manufacturer brass screw in the neutral bar that bonds the tub to previously mentioned conductors, or by a supplied bonding strap, or a separately sized bonding jumper.
Either way, if fault went to ground, the impedance of the path back through the dirt via the grounding electrode, to the grounding electrode of the supply transformer would not be low enough to trip an overcurrent.
Sorry for the long winded response but short circuit current does not go to ground.
@@schulerruler The ground wire offers an additional path for the electrical circuit to flow into the earth so as not to endanger anyone working with the electricity , in the event of a short circuit. Without a ground wire, your body could instead complete the ground path and may cause shock or electrocution.
@@MySpace662 please explain to me where the electrons go once they go into the actual ground.
The fact is that without a complete circuit back to the supply, meaning neutral, there is no circuit. Meaning no potential across conductors, meaning the electrons will not move as there is no force imposed upon them.
Ground helps us establish equal voltages as well as a larger plane for surges, but it is in NO way a low impedance path.
There are many systems that do not even incorporate a connection to ground. Engineered designed approved installations.
Look at the secondary on a transformer. If you do not give it a reference to ground, there is still Preciado across the coils, which still operates a load. In this case a contact between hot and ground won't do a thing. Line to line will pop a breaker, but a ground path is not required to trip it. It is the low impedance path established through BONDING that ensures this.
Thank you for this. I lost my dad to cancer last May. He was a master electrician, hell just short of an electrical engineer. I’m moving to his house and know I need to add a sub panel due to a remodel. I learned how to wire an electrical panel from him but he never covered a sub panel install.
I’ve learned a lot from him and miss him dearly. Thank you for explaining this.
Sorry about your father. I still miss mine 18 years later. Glad it helped.
GFM
It would be good to show that every pole transformer is grounded to a ground rod and almost every house after about 1980 has it's ground connected to a waterpipe ground , which is about a hundred times better than a ground rod. Liked the video!
The drawing is not perfect but the discription is exactly how it should be. Not bad from somebody from a country where they shit on ground and neutral. Good job mate. Simple and clear explaination
+J IJzer care to elaborate on the "somebody from a country where they shit on ground and neutral"?
Carolina Rodrigues Hi Where i come from the most important in the electrical installations is the grounding and taking care the neutral. I had some machines from the us and there was nothing done on neutral and grounding. Before we could start using them we most of the time had to rewire the machine so it could match the standards from my country. When i see the installations in the us many times the ground is used as neutral or visa versa. So my feeling is that in the us they not realy take care neutral and grounding. Where i live now in south east asia its even more worse. If you ask for a ground or a neutral they look verry strange at you. Ground and neutral are always combined. But that can give problems when you have one fase machines where you can turn around the power connector. Or try to buy a 5 pole power plug. 3 phase neutral ground.
Or even a 5 wire power cable is hard to get. I hope i am clear in my explanation.
Carolina Rodrigues and btw this guy explains verry good the differents so you can see you cannot combune neutral and ground and you cannot use ground as neutral or neutral as ground.
+J IJzer If you saw an installation in the US where ground and neutral were being used as the same it was done by someone that shouldn't have been doing the wiring. NEC does not allow this and it is not common practice I can assure you. I've been a Journeyman wireman in the US for 30+ years and that is not how we train our people.
Tony Thomas ok i worked for GE in europe before and sometimes we got machines from the US and sorry to say they where bad wired but good to know that there are stil good rules for that. Be safe : )
Excellent video. Another reason for the earth ground is to pull the neutral from the power pole down to ground potential. There is capacitive reactance between the primary and secondary of the transformer on the pole. This couples voltage across to the secondary from the primary. If you didn't have the earth ground then the neutral in the house would be floating up at some voltage level above earth ground. As such touching the floating neutral or anything connected to it and say a water pipe at the same time could give someone a shock. This voltage potential shouldn't be confused with the magnetically coupled power coming from the primary and going to to L1 and L2 on the secondary. Instead it's a product of the capacitive coupling between the primary and the secondary of the transformer on the power pole.
So, Joe, I have the typical Ontario 3 wire and ground supply and am showing up to 40V between grounded equipment; furnace, boiler, sump pump, and the cement floor. I have several standard galvanized ground plates; garage, hydro pole, solar panel array and horse barn. Power is coming from somewhere!!!!!!!
The big question is where is all the "grounded" equipment actually grounded. If your barn has it's own separate sub-panel and it is grounded through a long piece of wire to somewhere else far away then that could be the problem. You might have to drive a metal rod into the dirt under the cement floor and "locally" ground the sub-panel to the rod.
I posted a separate comment about this issue. It is different from the comment you replied to. I'd suggest you read the other comment.
Again Joe, I have read your other post too and what you say makes sense, I agree. My barn has it's own buried ground plate as well as the incoming supply ground from the pole. The concrete slab (26' X 36") has re-mesh which is also bonded to the ground plate. To add to the confusion my COMPETENT electrician is also baffled and suggests taking readings between house ground and various remote test grounds. The condition fluctuates depending on how much load is applied by my dairy farm neighbour a little over a quarter mile away! We have the same electrician who, by the way has many years of industrial experience too.
JPP2672 confuses me!
I'm NOT an electrician, but I tend to agree with the comment that current doesn't only take the path of least resistance. It takes all possible paths, just at different rates. From comments I have read, if your neighbor's dairy farm has a loose or open neutral somewhere, then his current is going to travel back on his ground and energize the earth. Current could then travel up from earth via your ground rod and into your panel and then through your neutral while trying to find a way back to your power pole/transformer. The catch is, if he is 1/4 mile away, I think that would be very unlikely.
@ munsters2 - Correct. The ground is like a huge carbon resistor and as such it can be thought of as an infinite number of carbon resistors all running in parallel. Accordingly, you can apply voltage to it anywhere and draw current out of it anywhere else to complete a circuit. And as you have stated all the current won't necessarily flow in a straight line between the two points. You can also have additional current flowing along curved paths on each side of the line as well. Also remember that the water content in the soil and how densely the soil is packed affects the resistance. So even a quarter of a mile might be carrying a substantial amount of current.
When it comes to power transmission, there is no difference between the neutral and one of the hots in an American residential installation. The neutral wire does not "return" power any more or less than the hot wire does. The actual difference between a neutral and a hot is that the neutral is connected to earth through the main panel. That connection to earth gives it zero potential between itself and earth. That should not surpise anyone. What is surprising is how many people never made the transition in science class when they stopped talking about D.C., and started talking about A.C. The whole circuit from the generator at the power plant to your light bulb and back again are connected. The electrons shove each other (but each electron only moves a tiny, tiny, distance) all the way through those wires in a loop and they switch directions and move in the reverse direction. Back and forth, that's alternating current. The flow reverses because the generator uses slip rings and not a commutator, the flow reverses as the rotor turns through the magnetic field. The multiple transformers between the power plant and your house do not change the fact that electrons are shoved by the generator and that moves them at your house in a back and forth motion.
Now this is a valuable comment. Thank You.
The Exploratorium in SF used to have an exhibit where you could sit and pedal a generator like a bicycle and then flip on connected incandescent lamps one at a time. Man, it got super hard to pedal as each light was switched on! Great way to get an intuitive understanding of "work" -- and how powerful electricity really is -- but also the "connection" between the generator and its loads.
The distance the electrons actually travel is less than the width of a hair - by a factor of over 100.
@@okaro6595 Yes, each electron only moves a tiny distance, then it goes back. I just re-read my original post and see that it could be misunderstood in that detail, so I'll rewrite that portion. Thanks.
It is good to point out that the Neutral to ground point in the main panel is isolated from chassis ground!!! Great explanation and very concise. Thank you!!!
+Steven Delgado Are you sure the neutral and ground are isolated from each other in the main service panel? Maybe you'd better watch the video again?
I work on the distribution lines, so we don't typically work in breaker panels. I've struggled to remember difference between neutral and ground, but when you clarified neutral is a load carrying conductor, and ground is just that (shortest path to earth) it simplified things..
I would imagine grounding onto a water-pipe would be great idea in the perfect world. However I have been on calls where plumbers have been shocked, or experienced balls of fire from disconnecting the ground. Typically due to a damaged neutral line on the house service.
Electricity is invisible, and if you see the fire, it may be to late..
This video is very informative with my trouble shooting..
Thank You..
Good explanation - thank you!
Perhaps a minor point but... at 8:00 you say "if this wire failed" and point to the neutral wire from subpanel to receptacle. I'm about 99.9% sure that you actually meant to point to the neutral from main panel to subpanel. Breaking the neutral after the subpanel wouldn't create the "neutral fished thru ground" scenario you are describing. Breaking it ahead of the sub would. Maybe an annotation needed?
***** Yeah, I noticed the same thing.
Good catch. Can you explain the circuit loop?
The "Neutral" that is coming in from the pole is NOT a neutral. It is called the messenger cable. Utilities do NOT want neutrals. We send power. The neutral is formed by the homeowner, at the panel, by bonding the neutral and the ground together at the panel, and then to generally a cold water pipe..this is the primary ground.
Ground rods have nothing to do with the primary service ground.
The reason we don't "bond" a sub-panel i.e. neutral, ground is because we need for the un-balanced load to go to a designated location and stop.. I repeat stop. Otherwise you'll have a condition called a "ground loop". All bonding is to be preformed at the load center, hence 4 wire connection. Other than that you were dead on. Remember, don't disturb the electrons while they are working...you will not be forgiven.
JPP2672 .. Thank you. why would I not get voltage between black and white but I will between black and bare and on a nearby Outlet white and bare. can you give me any help at all
It sounds to me as though you might have an "open neutral." That is to say you don't hand a compete circuit for the GROUNDED conductor. Neutral.
Neutral. a current carrying conductor that carries the UN-balanced load to ground.
In a typical 4 wire home setup, there are two hot wires having AC current but offset by 180°. Messenger cable (aka neutral) is bonded to earth ground. Does all the current that comes in from the hot wires exit the house via neutral? I can't envision all the power going into a copper pipe to enter the earth. It's a long way back to the power plant.
Maybe it is a long way back to the power plant then again maybe it's not
The neutral is kind of a gathering place for 120 volt circuits. When a load, say 10 amps, passes power thru, it goes to the neutral. If another 10 amp load is energized from the other hot line, the power passes from one hot thru the 2 loads to the other hot line with no power passing to the power pole thru neutral. If the the loads are unequal, say one is 10 amps and the other is 5 amps, 5 amps goes to the power pole thru neutral. I have more videos on grounding and bonding on my channel. Virtually no power passes thru the earth ground.
Hope this helps.
GFM
The hot is on the right side, The neutral is the wide slot on the left. This diagram has them reversed.
+Skipper Russell it could be an X-Ray view of an outlet. All you have to remember is black is the wire that chars you.
+Skipper Russell
Depends on whether you're looking at the receptacle or the plug end.
+Paul Frederick Go play golf in a thunderstorm , then explain where the ground is.
When I look at the plugs, I say "Wide White". The neutral wire goes to the wide slot. "Wide White" is what I get from high school foot ball where we were taught "Wide Right" meant the wide received on Right Side. This helps me remember. The ground connection is easy to remember. I also, use a black transparency pen to mark the hot on a new plug that I am installing. Ink from the pen comes off with plane water and no soap.
The red wire can char you, too. It's the opposite end of the secondary from the black.
yes, good. I had a range in an old apartment using the ground as a neutral and if you touched it AND the faucet, LIGHTNING! The chassis was energized..Ive also had electricians in a fire repair (under my General contractor work) fail to wire this properly and the inspector passed it, but when I called and reported the issues he returned in flames and kicked asses! Good job. Important clarification. The meter will read the G and N to be in common but they are different in function! Thanks for the good work here!
Welcome
GFM
What a great video, this normally confuses people because it is hard to rap your head around until it is explained very clearly. Main panel , sub-panel, whether to bond sub- panel is something very important that everyone dealing with this had to learn at some point. I'm sure you just helped a lot of people with your clear explanation and graphics!!
Thanks for the support.
GFM
why can it be ok to bond neutral and ground in main panel, but not in sub-panel. When it uses the same power. In other words, whats the difference if you have a short in a main panel where ground and neutral are bonded vs a sub-panel where ground and neutral are not bonded, or why not wire the main panel like a sub-panel having the ground separate from the neutral or wire the sub-panel like the main panel by bonding the ground and neutral in sub-panel. I mean if the electric short will travel properly in main panel why won't it do the same in the sub-panel if it's bonded the same as the main power?
+gtmustangcobra We need the convenience of sub panels, but at the same time we realize they add risk. It is not a perfect world. So we don't want to push our luck beyond the main service panel as far as neutral bonding goes.
+gtmustangcobra LOL..My question also!! I have asked electricians' this same question and I got nothing but shrugs or.. 'just because' for an answer. I think it's got something to do with the uncertainties of sub-panels in terms of grounding and the higher risk of introducing potential (think ohms law...) of the neutral (grounded wire) and the grounding wire to ground.If you get a definitive answer, please let me know and vice-versa.... :)
+gtmustangcobra Neutral is only grounded at the very start, before passing through any circuit breakers (particularly leakage protection), usually at the step-down transformer. If neutral is grounded at consumers' side (sub-panel, etc.), then it will mainly result in nuisance tripping of leakage protection devices (if any), because neutral current is "leaking" to ground.
But if a fault energizes anything metallic, why wouldnt that automatically trip a breaker....is it because the fault current isnt high enough?
steve jones
if your breakers tripped automatically you would very quickly become annoyed by that. Every time your air conditioner, or refrigerator cycled on you'd be resetting the breaker. Because loaded motors require surge current to start. But it is very difficult for simple mechanisms to differentiate between those allowable surges, and fault conditions.
I think people assume gound = negative comes from automotive wiring, where that's actually TRUE.
Brian Fahrlander
those people think a.c. & d.c. are the same too!
how is dc not ac at 0 Hz ?
Because nothing is "Alternating", therefore it can't be called ac at 0 hz.
Viktor Löfstedt ...try it this way, how is it A.C. @ 0hz?.......d.c. Is not a.c. Whether it's 0hz or a Ghz.
Good point, and actually 0 Hz is DC. Once you go to 1 Hz or more it's AC. The main reason NOT to use that terminology is to avoid confusion because they behave so different. There was a time in the USA where utility power might have been DC (NYC started out that way) and since they were pioneered by different people with different schools of thought they didn't use the same terminology.
Thanks for the clarification.
Now, how does changing the plug you illustrated to a GFCI plug change the wiring coming from the sub-panel?....Or does it?
Well it would have to because the GFCI plug uses a solenoid switch to keep the circuit closed, & it doesn't use a ground. This is why you can upgrade a 2 prong plug to a GFCI.
But also, we have to remember that the GFCI plug protects us (people) from Ground Faults by detecting a current imbalance of 5 milliamps.
Where a regular circuit breaker trip if temperature reaches a certain point because of a direct short, or a short to ground situation, or a power surge (due to dirty power, lightning strike, etc) So a regular circuit breaker's design is geared toward protecting equipment for electrical damage from excess amperage; & to protect against electrical fire. But it does NOT protect people from over-current faults.
This is why the GFCI circuit breaker & the GFCI plug is the best method of protection. You can replace an appliance, but you can't replace a person.
I didn't see your email until now we are at work and I'm going out of town
My brief stint as a maintenance electrician did not help me understand this completely. There are many discussions on forums as to Bonded Grounds, etc... Your diagram and explanation makes it clear for me -- 45 years later!! I have encountered stories as to how current, denied a neutral return, can travel along water pipes to other residences to reach a neutral-to-pole return. There is a lot more to say about the subject... Thanks much!
Welcome
GFM
Great video! I've been working as an electrician for quite some time, and I miss several of our foreman why you only Bond the ground to the neutral in the main panel and I have not gone to clear concise answer such as you have shown in this video. Thank you very much, I greatly appreciate it! May Jesus greatly bless you!
Thanks for the support.
GFM
Great video.
Thanks.
GFM
Try putting a meter on L1 and another on L2. You will see how you are paying for the use of power that goes back into the system to go to the next meter. Why do you think you have to complete the circuit.
The neutral of the 240 phase winding that is center tapped carries the unbalanced load. Balance the loads on L1 and L2 and your meter will read the same. The power company is not stealing it from you. The next meter down the road on the same delta transformer is not sharing with your phase winding. It has its own.
True!! you send the power back to the electric pole indeed back to the electric company but is thru the neutral not the L1 or L2 legs.
ruclips.net/video/cMzevUC4sao/видео.html
This guy in this video is almost dead on but you dont send it back to the transformer to balance a load thats why there's L1 and L2 and also in South America theres only 2 wiring at the houses: the common wire and ground! That's it...I am not saying that is safe but even here in the States old house used to use the 2 wiring system back in the days....
Drink some water before speaking, all the smacking is gross. And mention the country which you are talking about, where i live there is only one panel in each house, and connecting the earth to neutral is not allowed here.
you MIGHT have told us what country YOU are in .....?
Thank you very much. I was trained for ten years in the service with DC circuits. We had very little almost non-existant training with AC circuits. You cleared up a lot in ten minutes that I had been struggling with for ten years. lol! Thanks again sir,
Welcome
GFM
Watched Many Videos On This Issue ,I just could not figure it out? The way you presented it makes all sense now,Thank You for your time...
Glad it helped.
GFM
Being a master electrician for 10 plus years most of what this man is saying is not correct. He is trying but this information is misinformation. Do not do what is told to you here. The terminology is wrong and he is not an electrician. Its called the grounded conductor and the equipment grounding conductor. I didnt hear either of those terms mentioned. Maybe you should take an electrical class before you misinform 1.2 million people. Please go to school
Amen!! Grayfurnaceman IS a good man but should stick to his area of expertise which is HVAC. People should check this out : ruclips.net/video/mpgAVE4UwFw/видео.html
u must be the smartest guy in the room
From what I'm now understanding ground doesn't really protect you,I watched Mike Holt videos and ground will carry a load because of the resistance of the soil,won't trip a breaker
Eric Van I had the same thing happen to me, someone tried to tell me that when incoming voltage drops current goes up and destroys equipment, they were thinking about how a transformer works, I explained ohms law of I = E over R, and I decided to move on myself after all the reteric
Tony66777 dude… are you serious? Everything he said is correct for anyone trying to understand how the system works….not for someone trying to wire a house. Don’t come in with this 10 year bullshit. Blah blah blah.
"Electric current, after passing into the earth travels to the diametrically opposite region of the same and rebounding from there, returns to its point of departure with virtually undiminished force. The outgoing and returning currents clash and form nodes and loops similar to those observable on a vibrating cord. To traverse the entire distance of about twenty-five thousand miles, equal to the circumference of the globe, the current requires a certain time interval, which I have approximately ascertained. In yielding this knowledge, nature has revealed one of its most precious secrets, of inestimable consequence to man. So astounding are the facts in this connection, that it would seem as though the Creator, himself, had electrically designed this planet just for the purpose of enabling us to achieve wonders which, before my discovery, could not have been conceived by the wildest imagination." Dr. Nikola Tesla
We have all marveled at what Dr Tesla discovered. However, he was never able to make his high frequency, ultra high voltage power system work. And how lucky we are that it did not. No electronic device we now use would operate with all the earth as a conductor. However, we would not need lights outside at night as the entire earth would glow.
In any case, the voltages we are using in these panels are far too small to travel through ground effectively. Thanks for the comment.
GFM
an awesome paragraph!!
Pretty deep stuff from Tesla, which I'm sure is fascinating study, but as far as this video is concerned, it's more practical knowledge. Understanding the difference between neutral and ground, even though they are tied together in the main panel, and are at the same electrical potential, but are not tied together in a subpanel, can be a challenge to wrap your head around. The main thing to remember is that neutral is the return path, and ground is protection.
So, Tesla was wrong. He was brilliant, but deluded on at least that point.
This guy put me to sleep
anyone? anyone?
Hope you're not asleep when you stick your hand into a panel. Unfortunately this info doesn't work well as dog and pony show entertainment. Stay awake, don't die, pretty simple.
That could end up being a shocking experience in the near future !
Dam! 420 is everywhere....
You can speed it up by 2X then you wont be bored.
excellent resource,
I found and resolved this issue in a house yesterday
.found neutral bar in subpanel included bare ground wires,
I screwed a separate bar to the subpanel box to isolate ground wires.
also replaced breakers with new ones.
+ GFCI plug next to the sink
A quick way to say it is, Neutral ONLY meets Ground (earth) at the Main Power Panel. Your explanation describes why.
Very nice explanation.
Thanks for the support.
GFM
That was horrible
And why have a Have a sub panel
Say you want to add a couple rooms to your house or send electric to your garage you would install a sub panel there. Make sure your sub panel is actually designed to be used as a sub panel. You can use 12/3 for instance (depending on amps drawn and placement of wire, up on a pole or buried require different types) to the sub panel instead of 2 lengths of 12/2. 12/3 black is line one and red is line 2 so you can have 240v receptacles out of the sub panel and two separate circuits for receptacles and lights. The bare ground wire buss bar is not to touch or connect to the subpanel but rather connect to the service/main panel. The neutral/white goes the neutral buss bar and bonding screw (green screw) removed so that it does not connect to the sub panel either. Double check all codes and rely not on what I said here, code changes everywhere. Safety first and second then double check
JeeeZZZZ Why must you talk so SLOW??
Lawrence Ballack Yeeeeesssss
GFM
Better to be slow and clear for those of us with questions than to whiz through it so fast no one can understand. jeezz.
***** Studies have proved that talking fast while teaching a subject keeps us alert and therefore improves comprehension; whereas speaking slow induces daydreaming, loss of focus, and reduces comprehension. Besides, for all you slow folks, its a youtube video. You could always play it over as many times as it takes to get the subject....duhhh!
Lawrence Ballack Studies have shown that people who find reasons to bitch about free well layed out and easily understood informational youtube videos are complete twats.
This video helped me understand things that my teacher couldnt! Thanks man
Lawrence Ballack Could you please repeat that? thx.
I appreciated your video, and your explanation which sadly too many idiots can't seem to understand.
No matter how much you try, or how much effort you give in order to explain something, you will never be able to educate the fools who think they already know more than anyone else.
I was born and raised in the U.S. but have lived in the U.K. for 25 years, and although we only have 240 volt supply ie Live and Neutral instead of a center tapped transformer which would give 120V capability, the grounding principle is the same.
I wish that our plugs weren’t so damned big and awkward!
Keep up the good work!
Thanks for the support.
GFM
This is the explanation I have wanted and needed for 45 years. I always had a rough idea about this, and that's all I needed for telecomm work.
Thanks for the diagram AND the explanation.
I've watched this guys video's on several occasions and on several subjects...I have learned from every one of them....My thanks again to the gent that makes these.
Vern
Welcome
GFM
Nice video. One very important concept to take from this is the primary purpose of ground is to provide a low impedance path for fault current to flow so the breaker will turn the circuit off. That is pretty much its entire purpose - blow the breaker as quickly as possible.
That depends on if you mean earth ground or neutral. If you mean chassis ground to neutral in the panel, correct. If you mean earth that is not correct. Earth ground will not kick the breaker. I have a playlist on these issues: ruclips.net/p/PLItXrh64d2JNJOjSivaYXeX88i8MNWgwu One of the videos there is from Mike Holt about grounding myths. It is very good and explains it well.
GFM
Too add to that, the ground wire also serves to short circuit your body so that little or no voltage appears across it before the breaker blows. So your body won't feel anything since the ground wire bypasses it providing a low impedance path for the fault current. So even if the breaker failed to blow, you would still be safe until the ground wire burned up.
Huge thanks for this video. I have a 2 year tech diploma in electrical engineering and power system electrician journeyman ticket plus 7 years in the field and I couldn't explain it that clearly
super important.....me and my buddy upgraded the service at my apartment building few years back....im a licensed contractor and he has his journeymans license....the only thing the inspector really checked was grounds and neutrals separated in subpanels...2 ground rods and water pipe..he was there 5 minutes tops..
I'd like to say thanks for taking the time to fully explain it. I've been in the field for 8 years and have a strong background already, and this just solidified it.
Even a lot of electrician dont know why you dont bond subs or what a ground rod does. They just know the nec says so.
Ryan You are correct! NEC only tells you what you may or shall do. It does not tell you why. So, why are all the equipment grounds connected to the neutral in the main panel? Just want to make sure you understand that part. Respectfully, Kevin
@@KevinCoop1 in a nutshell, you want the ground and nuetral bonded to clear lightning strikes or line to line shorts on the utility side.
In a sub you dont want them connected. If you were to lose a nuetral, it would use the egc as a current carrying conductor and put a potential on anything grounded. Including cases and exposed metal.
Ryan The question was why equipment grounds are bonded to neutral. In your comment, line to line and line to neutral faults have nothing to do with grounding. Also, grounding Electrode conductor is connected to the neutral to dissipate lightning. So, if you have a line it ground fault in a utilization equipment, you will have higher amps flowing on the equipment ground system. What is the path of the high amps or where do the travel to. This is very important to understand most of the Article 250.
I am not an electrician but was told that there are additional reasons why power generation stations and line stepdown transformers are grounded that do not involve lightning strike mitigation. It is still a head scratcher to me but it involves autobalancing of the two sides of 2 phase power. Supposedly if a residence used a large portion of their power from one phase while using little power from the other phase then some problems would result but for the grounding on the stepdown transformer. Anyone have any further info?
Think you for explaining this to a left hander. It makes it a lot easier to understanding with the diagram. I do believe I have a breaker box with the N. and Ground all together. It is a 40 year old box with circuit breakers. Your Audio is good and the camera was stable. Thanks!!
Welcome
GFM
Thanks - I don't like messing with electricity (since getting a good shock @ 6yrs old..) but being a home owner means I sometimes have to. This clearly illustrated something I never understood .. and for teaching me this lesson I truly say THANK YOU.
I honestly think a lot of the confusion happens becomes the name “neutral” wire is misleading. This was a great explanation! Thank you.
Great video, One thing to explain however, there are many house built today that have the main disconnect at the meter. The example you gave indicated the main disconnect is in the "main panel". When you the main disconnect is at the meter, the load panel acts as a sub and the grounds and neutrals are separate at that location and not tied together. As a home inspector this is one of the main items we look for when we have a main disconnect at the meter, usually outside the house. One very important thing to remember, if you don't understand this issue, DO NOT OPEN your panel box. Call a licensed master electrician. This can Kill you if you touch the wrong wire or bus bar.
Very clear and through explanation. In some countries the ground is made at every pole so instead of using a earths ground in the house if lighting hits the pole it doesn´t make it inside the house at all. If the power company doesn´t ground every pole then if lighting hits the house and makes its way into the electrical system in your house it could blow things up.
+Joseph Nicholas Thanks for the support.
GFM
Thank you very much for this explanation. Makes perfect sense to me. This comes at the right time. At some time I want to put in a sub panel. In the sub panel separate the ground and neutral. DO NOT tie them together. You just made life easier for a great many people. Thank you!
and put a ground rod hooked to
the ground bar on the sub
Thanks very much!! For more than 59 years; {Nor was it explained to me in college.} I could not figure this out on my own. Now I know!
I Worked as a mill-write some years ago. I never knew why the panel was live with electricity, yet there was nothing shorting out.
Glad I could help.
GFM
Nice job it makes more sense. It can be summarized for memory by: the ground in the main breaker is for lightning strikes. And. Ground is not attached to neutral in sub panel incase neutral breaks causing a shock hazard at appliance case.
This video really help me to understand the whole concept of how neutral and ground works. Great explanation and very verbally clear on every single words. Thanks
Thank you for posting this simple to understand, and very informative video.
Albert Einstein said; "If you can't explain it simply, you don't understand it well enough."
I say; " If 'I' can understand you,... well, you possess a comprehensive understanding of it. ; )
Thanks for the great video! I am in Electrical School in the Air Force right now, and this helped clear some things up. Keep up the good work Sir.
Welcome
GFM
This helped me greatly....we had to wire up panels in my HVAC class and I was like "what's up with the green jumper"? I use to do electrical work and always thought that the ground was separate completely from everything else and just went into the earth from the panel. When I saw it connected to the neutral I was almost certain my classmates wired it up wrong because the neutral carries the load back to complete the circuit; but if there's a surge then there has to be a place for it to go or it will burn up everything like you said. You're video's are a life saver.
David Copperfield Thanks for the support.
GFM
this is a good illustration and I think that even the folks out there who have little to no knowledge will understand it as well.
Awesome explanation. Simple, slow, easy for me to understand. It answered questions I had. I have been doing it right for some time (I am not a electrician, but am in electronics and appliance repair). This answered many things I needed to know. Good job.
Thanks for the support.
GFM
Your video is still doing it's job. I'm still a bit confused, but it's becoming clear with your help, thanks.
Welcome
GFM
The reason we don't connect ground to neutral is because when current is flowing through it you will have a voltage above ground because wire has restance. It is possible to get shocked by touching the neutral wire if your far enough away from the main pannel and current is flowing through it. However in the 70s before this was added to the electric code they often grounded the sub a pannels using bonding clamps just like the main. Also 3 wires were allowed in all dyers and ovens. This was all changed but many old timers still do it that way. If your house is from the 70s it's likely your dryer is wired thus way without a extra ground wire.
You did a better job of explaining this than either the edison guy or my inspector. It's not terribly complicated but it takes some of us, and by that I mean me, more than once to get it. Good job and thanks for posting
edstimator1 Glad it helps.
GFM
I appreciate your attempt to explain the difference between ground and neutral in a panel. The NEC codes in the 300 chapter explains in detail what and where grounds are required and when they have to be separate such as sub-panels. One important thing that I think you left out is the fact that the ground has to be separate from the neutral in sub-panels so that, in the case of our fault, it will create a high current situation which will cause the breaker to trip there for protecting life if someone happens to touch it. Of course, in a normal situation the line would come in, power the load and then return to the source on the neutral.
At 1:55 I do explain that the ground and neutral are separated in the sub panel.
GFM
Braeburn Hilliard's Channel The NEC tells you what you may or shall do. It does not tell you why. Can you tell me why the ground and neutral are connected together in the main panel? What happens in the main panel when the short to ground gets to that point? I'm hoping you know the answer. Respectfully, Kevin
@@KevinCoop1 yes. Main panels are grounded because it provides an alternate pathway for current to follow if there is a breakdown between the neutral and hot wires in the normal operation of the system.
Braeburn Hilliard's Channel Not really. Earth ground (Grounding Electrode Conductor) is for lightning and intended to "ground" neutral called "grounded conductor". That part of grounding is done. Equipment ground conductors are installed with feeders and branch circuits to cause a short circuit if metal parts not intended to be energized are energized. A high number of amps travel back to the main panel, onto the neutral, out to the utility transformer, through the transformer coil, back to main panel, to the branch circuit breaker(hopefully) and have enough amps to create a magnetic field strong enough to cause breaker to trip. If this makes sense to you and you start applying it to Article 250, it will make a lot more sense of why it says to do certain things. Respectfully, Kevin
@@KevinCoop1 yes, that's exactly what I mentioned in my very first comment. I thought you were asking about any additional reasons why main panel would require being grounded. That's the only other thing I knew. Of course, a lightning strike may cause failure of the install circuits in which the ground would provide a route for current to travel just like I mentioned. I kind of think we're saying the same thing.
Thank you for this excellent video. In most cases, however, the only place that the neutral and ground are joined is at the incoming power meter. There should be one or more ground rods at the meter pedestal. The ground (green) and neutral (white) should not be joined anywhere inside the house. It depends on your definition of "main panel". The main panel and first breaker on any recent electrical services is at the meter. Your video is an excellent illustration of why there is a "stray voltage" problem at many dairy farms where the neutral and green are routinely connected at various panels around the farm. In too many cases, one old motor or pump wears out, shorting some current to the housing, etc and this sends current back through the ground, giving the cows a shock every time they try to take a drink of water. Cows then drink less water, give less milk and the dairy farm goes out of business. Neutral (usually white) and green wires should not be joined anywhere except the power meter. Each panel should have its own ground rod and separate ground bar inside each panel for the green ground wires. This is now code in many areas.
Thanks for the video. Informative. I'd also add that another reason for NOT bonding neutral and ground at sub-panels is due to the different cable gauge size between ground and neutral/power. If there was a problem and ground had to be substituted for neutral, generally ground is a smaller(high numbered) gauge cable relative to the installed neutral cable. For example, in a 30 amp scenario, the 10 gauge neutral cable, if lost, and electrically replaced by a 'standard' smaller size ground cable, the substituted ground cable could not handle the current/amps and could heat/burn in a situation where for whatever reason the neutral cable is lost. Basically ground wires are not designed to carry all the larger currents/amps in residential/commercial set-up.
John Zimmer Very good point. Thanks for the thoughts.
GFM
Excellent video. I would like to emphasize that the ground in the main box goes to a rod or metal pipe that is actually buried in the ground. The chassis ground is just a symbol to indicate that the incoming ground wire is connected to it. It does not otherwise go anywhere. The main goal is that the ground wire does not conduct current under normal use. If there is only one connection between ground and neutral in the main box, this will be done. So two different grounded items will have the same zero volts between them and you would not get shocked when touching both at the same time.
heres my take away- sub panels separate ground bar bonded to box. this makes me crazy now cause on current job added 6 lines to a 60's or 70's sub panel where nuets and grounds share same bar well there is a water pipe near ill see if its good. hope no one repaired something with pex or some interrupter. great video!!! like you said it was always rolling around in my mind.
Its not the end of all times if neutrals and earth ground are connected. Consider the dryers and stoves connected with 3 wire that used the ground as neutral. Not the best way but done forever. Its just better to separate.
GFM
You are correct in your explanation of why the neutral line is not also used as a ground but further explanation is needed. In order for the chassis to be hot two things need to happen one the neutral wire has to be open, which in this scenario is also the ground and secondly the hot side be shorted to the chassis correct?
Yes. But consider; an open neutral and hot shorted to chassis could easily be a burned wire anyplace in the circuit.
GFM
David Heins Why would the neutral need to be open? If the hot gets pinched while putting the metal cover or case back on, and everything else is still connected, it is a short circuit with most of the current going through the case to the equipment ground. Less resistance than the load. Respectfully, Kevin
Excellent !!!
What I don't understand is that ground line connection returning back from the sub panel to the main panel.
We don't have that configuration in our house. We have just a ground bar in the sub panel gathering the house ground wires together and from there there is a thick ground cable going to the earth of the backward.
Is it ok with this ?
Thanks
Gray I worked for a electric utility as a contractor and one of the first things the utility told us in are orientation was do not assume that the coating on overhead wires is insulation some coatings are just weather proofing and do not offer much if any protection
I'm sure you should not trust any coating, especially on the high voltage.
GFM
I was not trying to offend just heard you say 2 black insulated wires I just didn't want anyone thinking that the 2 hot wires were insulated and safe
None taken and thanks for the thoughts.
GFM
If you are using cable (as you would when wiring a house) the conductors will be insulated, except the ground. Two conductor cable has a black (line) and a white (neutral), plus ground. Three conductor cable has black (L1), red (L2), and white (neutral), plus ground.
I'm new at all of this. It would be helpful if you could explain the part that the L2 wire (leading to the main panel) plays in all of this, since power flowing to the load is traveling through the L1 and the neutral. Thanks.
You might try this playlist: ruclips.net/p/PLItXrh64d2JNJOjSivaYXeX88i8MNWgwu
GFM
Isaac,
What might help to clarify is that typically, both L1 and L2 would be run to a true sub-panel, not just the one drawn in the video.
L1 and L2 are legs of the split phase system. They are your 'hots.' They have 120V with respect to neutral, and 240 volts with respect to each other. If you didn't run both, you could not utilize 240 volts and you could not balance your loads running through the sub panel.
@@spruce_goose5169 thanks. That clears things up for me.
I asked this question to our experienced handyman if our homes are protected against lightening, & the answer was no.
Today I learned u our homes have a jumper from the neutral to the ground. Thank you so much for explaining how it works so clearly, other it would have remained mystery.
Do we get 3 phase power supply in homes & why, either way?
Thanks
3 phase power is not generally available to homes in the US.
GFM
Thanks for the explanation of neutral and ground. It is so easy to understand too just not obvious. The images helped a lot to understand connectivity of the circuits.
Thanks for the support.
GFM
Well done GFM...well done! Very clearly explained and just the right amount of detail...thanks!
Sowshul Media Thanks.
GFM
Thank you your explanation makes clear sense. Wondering if you could do one on grounding and earthing of an ac subpanel and solar concentrator dc panel that includes an ac inverter. I believe two ground rods are in play there at the subpanel and cannot be more than 6 feet apart.