Reverse Polarity in Electrical Outlets - What, Why and How
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- Опубликовано: 26 янв 2020
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This video explains reverse polarity in electrical outlets and more. It describes, what reverse polarity is, why it's a problem, and how to fix it. It also give a good background about how electrical systems are designed and installed.
If you'd like to learn about more electrical systems, and home systems in general, please visit my website at: houseknowhow.com. 
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Just tested every outlet in my home. My home is at least 30 years old. One outlet in the kitchen, one I plug in the coffee maker, tested reverse polarity. One of my outlets in the living room showed an open ground. You are right, the one in the kitchen seemed to work fine. I didn't know anything was wrong. Fixing it and the open ground this weekend.
This was great, thank you! I hired and electrician to do my fix but the first thing he asked was to suggest testing with the 'cube'. What a cheap great investment, less than $5. After finding reverse polarity in 3 adjacent duplex receptacles, I was able to further talk with my electrician and get a head start on troubleshooting.
The clearest video on reverse polarity I have seen...made simple...great job
Thank You so much for properly informing us DIY'ers on the Theory of electrical polarity in practical terms :)
Thank you! Very informative and clarifies why this is actually a concern. We've had a few outlets in our home with reverse polarity (checked by a plug tester) and have avoided using them because we weren't sure what that actually meant. Glad to know it's likely an easy fix for an electrician, not likely rerunning wire, etc.
Very informative. Thank you!
Very Good! Very precise! Very informative! Thanks.
Thank you so much for taking the time to clarify the information that I was looking for
But it's incorrect from the Title to the end... so what are you thanking him for? Blind leading the blind. This guy is WHOLLY unqualified to speak on this subject and should stop. Polarity? In an AC system? Pressure side? SMH
Thank you. It was very beneficial for me.
THANK YOU FOR YOUR VIDEO Y CLEAR EXPLANATION.
Thank you Sir! Great information!!
Great explanation sir
Thank you
Excellent and useful content. The delivery was fine. Thanks
Too bad it almost all BS.
Baffling you with the wrong information? There is NO POLARITY in an AC system and there is no "pressure" side in AC or DC. This guy is wholly unqualified to be making videos on electrical system testing or understanding. Ugh.
TY so much I learned something from the video and how to setup an outlet.
For what? Baffling you with the wrong information? There is NO POLARITY in an AC system and there is no "pressure" side in AC or DC. This guy is wholly unqualified to be making videos on electrical system testing or understanding. Ugh.
@@DiffEQ don't care my tester show the polarity reversed as well. your opinion is unwanted period
Thank you. Well done.
Thank you so much. Very easy to understand.
Too bad it almost all BS.
Baffling you with the wrong information? There is NO POLARITY in an AC system and there is no "pressure" side in AC or DC. This guy is wholly unqualified to be making videos on electrical system testing or understanding. Ugh.
thank you for this
What. You can't cook pizza in a toaster? Learnt something new!
Thank u for ur kind information
Your toaster drawing is awesome!! :) great job though. Thank you
For what? Baffling you with the wrong information? There is NO POLARITY in an AC system and there is no "pressure" side in AC or DC. This guy is wholly unqualified to be making videos on electrical system testing or understanding. Ugh.
@@DiffEQ One of the wires in AC is at the ground potential and another has alternating voltage compared to the ground. On a properly working system you will not get shocked from the neutral (grounded) wire. This is basic electrics.
Great explanation. Thank you.
Too bad it almost all BS.
Baffling you with the wrong information? There is NO POLARITY in an AC system and there is no "pressure" side in AC or DC. This guy is wholly unqualified to be making videos on electrical system testing or understanding. Ugh.
Logical system. Clear explanation. Thank you.
Too bad it almost all BS.
Baffling you with the wrong information? There is NO POLARITY in an AC system and there is no "pressure" side in AC or DC. This guy is wholly unqualified to be making videos on electrical system testing or understanding. Ugh.
@@DiffEQ To bad you have no content or followers.
thank you great tutorial
Great job thank you
How about more videos? I love these topics!
I'll be doing more soon. Checkout my website HouseKnowHow.com. I'm writing articles for the electrical section now.
Thanks a lot Mark!!
Sir: Wonderful explanation of the DANGER of reverse polarity in/of a toaster.
Thank you.
In Europe toasters cut both wires. I would be amazed if they did not do that in the US.
@@okaro6595 Double throw switch in the appliance?
@@tedlahm5740 I have not opened but the both sides cut when the tray comes up.
Thank you so much!
When I learned about polarity decades ago I quickly tossed some of my mom's ancient extension cords and replaced them. A few years back one of my nephews called me with a problem. He had rearranged his living room and the computer no longer worked in its new location. Different receptacle, I asked? Yep. You probably have a reverse polarity problem. Went over there to fix it, showed him how it was screwed up. Now he helps me with MY computer issues.
Computers work perfectly well with reversed polarity. Maybe if there is an UPS it might not work.
This was a great video amongst thousands. Much clarity than ever. First time I got the inside real story of polarity reversal. In DIY, I did install one outlet and I have to check its polarity ASAP. Thanks for this video.
ut it's incorrect from the Title to the end... so what are you thanking him for? Blind leading the blind. This guy is WHOLLY unqualified to speak on this subject and should stop. Polarity? In an AC system? Pressure side? SMH
Very informative video, thank you
Informative... but WRONG.
Thank you milord!
But why most of devices working normaly with any poliarity?
It's because they have at the beginning of their circuit mechanism that switches to proper polarity?
Or its because the nature of AC? Like it always jumps from negative to positive charge and thats why the direction not always important?
Thank you!
You just told me what I've asked a lot of people. The slots being different. We had 3 licence electricians give up. The HVAC man knew right off what was wrong. The steel neutral cable had broke about 10 feet from the pole. This causing two appliances to catch fire.
Toaster schematic was an excellent example....great job.
Too bad it almost all BS.
Baffling you with the wrong information? There is NO POLARITY in an AC system and there is no "pressure" side in AC or DC. This guy is wholly unqualified to be making videos on electrical system testing or understanding. Ugh.
@@DiffEQ A textbook example of the problem of having little information (as opposed to none). There are two wires, one of them is grounded and the other is ungrounded. The grounded wire is of course always at the ground potential.
Now there is a problem as any properly designed toaster would cut both wires when the tray is up.
5:50. There are a few situations where a white wire is used as a hot wire and is safe and up to code. A common example is a 12/2 NM cable powering the 20 amp 240 volt receptacle for a large window air conditioner, or sometimes usually in homes more than 25 years old, as the supply to a switch when the switch is the end of run; this method is no longer compliant as of the 2011 NEC, an available neutral is required in the switch box to facilitate future installation of electronic switching devices requiring a neutral to function properly. In these situations the white wire should have been re-identified as a hot wire with black or red tape near the end at all termination points, but sometimes this isn't done.
What the hell! I paused it right when you said I could cook pizza in my toaster. I was like "no way, I gotta try this"! Unfortunately I waited to finish watching your video until after I ruined my toaster. Thanks a lot!!! 😤
Awww, that poor toaster! Now, SUBSCRIBE, for more of my handy tips!
You are joking, right?
Just what i was looking for today, thanks young man. one question: on the household electrical cord one side has a ridge, the other side is smooth. Which side is the hot side, which is the neutral?
Assuming there's a plug on the end of the cord, look at the width of the blades on the plug. The wide blade is the neutral blade, the narrow blade is the hot blade. Then look for where the cord comes out of the plug. If the ridge is on the wide blade side it's the neutral side. If it's on the narrow blade side it the hot side. If the blades are the same width then the plug does not enforce polarity and the ridge on the wire doesn't indicate polarity either. I hope that helps!
How do you test the GFCI wires to verify you shut off the correct breaker so I don't have to flip the main off? I own both a multimeter and a car test light (for fuses)
Hopefully you can test for AC voltage with your multi-meter. Put one lead on a hot (black/red) wire and the other on a neutral. Test it on something you know is live so you know what you're doing. Be careful!
@@HouseKnowHow Many electricians use a non-contact voltage tester as it is much safer than other types of test equipment. Your caution about testing it on a known live circuit still applies.
Hi my four pin plug was damaged (clips snapped) on my car radiator fan motor my friend put a new plug on on the car rad loom which is 12 V car electrics- three settings on fan 100 250 450 - anyway he got the red and brown wire incorrect way into plug so I guess reverse polarity - it started smoking the motor and unplugged it after a few seconds - question is the cables where changed back to the right sockets and the fan now works perfectly - iy was a £400 fan my question is please the fan is working good but would he of damaged it as went very hot and smoked- the plugs were perfect and not burnt - thank you.
I'm sure your friend damaged the fan in some way if there was smoke. How bad I can't say. I don't know what the risk is if he continues to use it. The thing is cars run on DC (direct current) and homes have AC (alternating current). They are very different. If you run an AC motor with reverse polarity it will likely run fine. Whereas with a DC motor if you run it with reverse polarity, well in some cases, as your friend found out, you get smoke! Good luck with the car!
There are brass terminals for hot silver terminals for neutral and a green terminal for the ground wire. If installing a GFCI outlet or receptacle do not get the line and load mixed up and if there are multiple GFCI outlets on a circuit then do not use the load
All good points. Thanks.
I have a gfci outlet to the left of the kitchen sink and another gfci outlet to the right of the sink and i have a non-gfci outlet downstream on the kitchen island. Are you saying that i should not put any wires on the load of the two gfci outlets and no wires on the load of the non gfci outlet on the island? Help, please!
Small but important tip! Wattage is always the most important factor as the myth about low amperage is wrong as voltage and amperage are factors of sine wave which voltage x amps equals wattage or joules per second!
Dice Roll. Extremely well written. As the amperage goes up (because the resistance goes down) the wattage goes up. Thank you for keeping us informed.
thanks
I just changed a GFCI 5 wire, a ground, 2 lines and 2 loads and my "8-ball" reads hot neutral reversed, . This outlet runs a garage- located refrigerator and 2 2nd floor bathroom outlets. Are my line wires reversed or my load wires to get a "hot neutral reversed" reading? I know for certain my lines are up top and and loads are on the bottom, I just didnt realize the left and right could be reversed. Can I run into any problems if it takes me a day or two to address this? Thanks much
I would hope 2 days doesn't matter too much since it's been that way for a while. And, I don't know all your details. If you'd like a little help solving this to to chat for a very reasonable fee, please contact me via the HouseKnowHow.com contact page. Thanks, Martin
What was the fix? What happened to cause the hot/ neutral reverse?
I have the same problem: I have the main wires coming from the main breaker box then three runners; one outside one inside the kitchen outlet and one to the dishwasher and I check the wires and reconnect with a new GFI and same thing take everything a part thinking something was wrong in my part but seems right. Any suggestions? It will be appreciated :)
@@cpsadp99 reverse polarity on any fixture (light or switch or outlet) will charge neutrals on all fixtures downstream of that fixture.
See 👆🏻
Hi, thanks for making this video. I understand what you've explained but something still bugs me. Why is polarity an issue in an AC system? Isn't the polarity in a typical 115 V 60Hz house always switching from (-) ve to (+) ve 60 times every second? If so why then does it matter which wire is "hot".....aren't they both hot??
The neutral wires are never hot. They should always be a 0 'potential' or voltage because in modern buildings the neutral wires are grounded (connected to the Earth). And the ground (Earth) is defined as 0 potential. The hot wire voltage oscillates from +120 volts to -120 volts 60 times a second. So the hot wire whether it's at +120 or -120 is the dangerous one. I hope that helps.
@@HouseKnowHow thanks for the reply. It is helpful. I'm not trying to be "cheeky" but I'm really trying to understand this concept clearly. So are you suggesting then, that if we assume that a house is properly wired and a child sticks a metal object into the NEUTRAL slot of a wall outlet while barefooted standing on a bare concrete floor, he will NOT be electrocuted? After all by this explanation both the neutral wire and the child are both grounded and at the same "0 potential".
Theoretically your are correct. But I won't be testing this theory with my child! ;-) Inside a main electrical panel the neutrals and grounding conductors are 'bonded' (connected) together. This forces the neutral to be at ground potential which is defined as 0. This is also why when you drag your feet around on a carpet in dry air and you build up a static charge that it is dissipated (and you get a shock) when you touch something that is grounded like the screw holding a cover plate on an outlet or switch.
For the most of the world it does not matter. Here toasters have double pole switch. In Europe most plugs are not polarized. Where they force polarity (grounded plugs in France, Belgium, Poland and Czechia & Slovakia) there can be different standards or no standards in different countries on the polarity.
No both are not not. Neutral is always neutral, It is grounded. The other one is hot it varies in the US between +170 and -170 volts 120 times a second. Note that the equipment does not care winch one is grounded or even if neither one is. It cares of the voltage between the lines.
Polarity is a function of a Direct Current Circuit - think battery power.
Alternating Current (A/C) - in the US - consists of two 'HOT' wires (RED & Black) and a neutral (White) wire and a (Bare Copper) Ground Wire entering your Electrical panel. The ground is actually connected to the ground your house/home sits on (either by a grounding connection to buried metal water pipes or to a ground rod buried six feet or so into the ground.
Hot and Ground are appropriate terms when discussing alternating current - rather than POLARITY (the relative orientation of poles; the direction of a magnetic or electric field) which is a term that has meaning when discussing Direct Current (think battery powered) circuits.
Incorrect.
Neutral is bonded to Earth ground only at the first Service Entrance. It is never bonded downstream. Secondly, you either have a phase (hot) conductor or a neutral (grounded conductor), not a hot and a ground. Ground is not required for power distribution and many appliances don't use a grounded plug. The US is not 120VAC, it is split-phase 240VAC. 240V devices do not require or utilize the neutral (split phase) conductor so BOTH conductors are hot and there is no neutral.
Stay in your lane is my advice.
Polarity is the established term for it. It was used already in the patent application of the sockets.
I don't know if this applies for the EU. We do have a common rule of thumb where the hot should be, but loads could be connected eather way. Sooo.... idk
Some countries have standards on how the outlet is wired like in Finland the phase is on the right but having it on the left is not serious enough an error that one should call an electrician to fix it as you can insert the plug either way. Toasters here cut both wires.
Some type of plugs fit one way like the French grounded socket. Czechia uses the same plug but they wire it differently (phase on the left) so anything grounded designed for French will have reverse polarity in Czechia.
Is it bad to use a power strip in a receptacle with reverse polarity? What happens to the devices?
It's exactly the same as if you plugged your device into the reverse polarity outlet without the power strip in between them.
The power strip has really no issue in it. The only thing I can think that if it has a switch it may break the neutral. Power strips are really very simple devices.
Loved the pizza joke my man
In Germany, the hot and neutral conductors of Schuko plugs can be swapped.
Therefore, both conductors of the devices are switched off. Both conductors are also insulated.
In the usual system the hot conductor is at 230V and the neutral conductor is near ground.
In the system, which is obsolete in Europe, both conductors were 127V to ground and between the conductors 220V.
When the Schuko plug was invented, it was based on the old system with two hot conductors.
Therefore both electrical conductors must be switched off. But today it's hot and neutral. But the Schuko plug is not polarized.
(Three-phase current, 127V x sqr(3) = 220V)
Gotta say, he got me with the pizza in the toaster comment.
House inspectors would have you believe you need to call an electrician to change a light bulb.
😂😂😂
I guess I’d better remove my pizza from the toaster. 😔
What about the round outlet how can u tell which is hot and neutral
I don't know what round outlet you are talking about. Can you refer me to a pictures somewhere?
@@HouseKnowHow in Indonesia standard socket is EU type
@@SyahrilBaharuddinSellangme I don't know about EU type outlets. Do some research on Google.
Instead of answering your question about plugs that have the same sized blades you dodged it by saying not to use it. That doesn’t work when I have old stereo equipment that needs to be plugged in. Is there an easy way to determine the polarity of the plug end on a device before I plug it in without taking the device apart to find the hot side of the plug wires coming down from the device?
I don't know of an easy way to determine this. There may be markings on the wire itself, but how to know what those markings mean is the hard part. If you happen to plug it in backwards and use the device it will likely work fine. Just don't take the thing apart while it's plugged in. To be cautious you could get a voltage sniffer and make sure the box isn't hot after you plug it in. You may want to take it to a high-end stereo shop and ask them to figure out the polarity for you.
👍🏾
Lay the toaster on it’s side when cooking pizza. It keeps the good stuff from sliding off.
Great idea! And, I recommend putting your pizza in an oven. :-)
@@martinnewmark2716 Or in a toaster over or air fryer
I have a question. Since in AC, polarity changes at 50 or 60 Hz, ain't it means that neutral wires also becomes hot during the negative half cycle. And this is not the case the how ac to dc circuit works, because during the negative half cycle we do get current through the other pair of diodes.
No, the neutral wire is always 0 voltage. The hot wire goes from +120 volts to -120 volts 60 times per second. So you could say the polarity is changing but with the neutral always at 0 voltage it's the hot side that is simply switching from + to -. Whether the hot side is at +120V or -120V it's always dangerous to touch. I hope that helps.
The neutral wire is grounded. It cannot become ht as hot is measured relative to the ground. Also the polarity changes 100 times a second in Europe and 120 times in the US. The polarity changes twice in a cycle.
Can you share with gfic
I don't understand your question.
What happens if the white wire is connected to the black wire??
Sparks, heat, possible fire, possibly a flash-bang that knocks you back, makes you blind, etc. The circuit breaker should trip when you do this, but the other things can happen before the breaker trips. So... I don't recommend doing that! :-) I need you alive to watch upcoming videos.
Can you make a circuit that reverses the polarity every 0.5 seconds?
I'm sure you could, but I don't know how to do that. Talk to an electrical engineer.
@@HouseKnowHow DPDT Relay with a multivibrator circuit.
@@EricDavisED A cat detector using a laserbeam breaker circuit connected to an FM transmitter. I could use a 433MHz transmitter and matching receiver relay. That would be better but I figured it out already using the FM radio. I also tried it with the 433MHz modules and an IR sensor module and it works very well. That is more practical.
Don’t the wires switch 60 times per second?
The black wire switches from +120 volts to -120 volts 60 times per second. Hence the 'alternating current'. The White wire is always at 0 voltage relative to ground (assuming the system is wired correctly). That's why the black wire is referred to as 'hot' and the white is referred to as 'neutral'. Note that current still flows through the white wires.
Yes they alternate, but the neutral wire, which originates from the center tap of the transformer secondary windings, is always the current return. The hot wire, which originates from one end or the other (pole or line) of the secondary windings is always the power in. The voltage from each end of secondary windings is 240v and center tap, as the name implies, is 120v. In a 240v line there are 2 hot wires, one originating from each end and there is no neutral wire. The voltage and current alternate direction and polarity symmetrically, so reverse polarity wiring does not exist.
Do the wires stay the same. The voltage just reverses 120 times a second. The grounded conductor is at zero patenttial white the ungrounded conductor has an alienating voltage referenced to earth.
Same logic for ac?
I don't understand your question. Please re-phrase. Thanks.
@@HouseKnowHow sorry, I meant, is it the same logic for alternative current? Is reverse polarity a bad thing on alternative current? Im new to that so sorry if its stupid question
@@drdzdd I don't know where you are, but most homes have alternating current (AC). So, in my video I was referring to alternating current. I've never heard of 'alternative' current that you refer to. I'm guessing it was a typo, or something I don't know about. For devices that use 'direct' current (DC) (cars, most electronics, anything that uses a battery, etc.) polarity is more important in that if the polarity is reversed the device likely won't work, and can be damaged. I'm not an electrical/electronics genius, but I think when we plug our computers into an AC outlet in our home the power supply in the computer converts the AC to DC before sending the electricity to the main components inside the computer. I hope this helps.
@@HouseKnowHow thanks so much for your reply man. Its not a typo but incorrect translation, ok so I got it now, besides im in France. Thanks abunch for your time
I once accidentally touched my alternator when my car was running, tossed me back 10 feet like a rag doll, I've never worked with anything electric when powered on since
Wisdom comes with experience!
True I've been shocked from 12v the other day wiring in a new fan for the living room I mean it didn't really hurt but it scared the crap out of me
Great explanation. The speed of delivery is to slow. Can you redo the video a little less mono tone.
Thanks for that feedback, I agree. As I get more experience my presentation is getting better I think. Checkout my latest videos.
Too bad it almost all BS.
Baffling you with the wrong information? There is NO POLARITY in an AC system and there is no "pressure" side in AC or DC. This guy is wholly unqualified to be making videos on electrical system testing or understanding. Ugh.
Great explanation but 1.25x speed and here you go.
Thanks! I'm working on getting better at my delivery.
What is the consequence if the polarity is swapped?
I thought I covered that in the video... If you still have a question after watching it again, let me know.
@@martinnewmark2716 That was the question...And no you did not.
@@joederbo6151 In the video where I talk about the toaster having reverse polarity and all the wires inside the toaster being hot as a result, because the reverse polarity causes the toaster switch to be on the neutral side..., that's the result of reverse polarity. The toaster will work, but now the neutral is switched instead of the hot. That is the consequence of the polarity being swapped.
@@martinnewmark2716 It is a badly made toaster if it assumes the socket is properly wired.
and don't put a knife inside the toaster to clear stuck bread !!!
How about a mini pizza 🍕
I can't hear his voice very well. Even with volume on high volume, I can't hear him.😢
Consider some hearing aids bud
A little quiet, but clear if you turn it up a bit.
Skip to 8:00 to skip all the pointless rambling. Long story short, flip off power, swap which sides the cords are on, and the reverse polarity reading will be fixed.
Talking way too slow
Thanks for your feedback! I'm working on getting better at this.
You know you can increase the speed in RUclips
Too bad it almost all BS.
Baffling you with the wrong information? There is NO POLARITY in an AC system and there is no "pressure" side in AC or DC. This guy is wholly unqualified to be making videos on electrical system testing or understanding. Ugh.
Why would they complicate things? Eeeeeeeveryone knows red is hot (positive) and black is ground (negative). All wiring for anything should start with red and black.
Black isn't "ground" though. Red/ black are often both "hot". 3wire= 2 hot, black and red=hot, 1 white neutral, 1 ground.
Black is usually hot bro.
My first action on seeing red & black wires is usually checking for 220V.
I think what John is getting at is that (in a very basic sense) the color red LOOKS like something hot (fire) and dangerous. Plus, red is positive and black ground for DC (automotive) batteries.
I agree with John… Whoever originally standardized the colors of AC house wiring made it complicated by using black for hot.
You are WHOLLY unqualified to be giving advice on electrical systems. Most glaringly, there is no polarity on AC systems and even in DC systems there is no "pressure" side. How are you this ignorant and not know it? Dunning-Kruger, no doubt.
STOP. This is the blind leading the blind. How do you explain 240V circuits where neither conductor is a grounded conductor, a.k.a. neutral.
JUST STOP! This, viewers, is why you don't use RUclips from randos for explanations/understanding. SMH Unbelievable.
@@fisheye42 Because you don't understand it doesn't make it complicated. In the EU, the hot is brown and the grounded conductor (neutral) is blue even though it's not split phase. (220VAC, 50Hz)
By your logic you should not be allowed to flip a appliance power plug. But you are and you can.
Most plugs have a long prong and a short prong, so they fit into the outlet only one way, and for exactly this reason.
Some appliances don't require polarity when plugged in. They should have internal protection for it. Or the appliance you are using is very old.
Thank you!
For what? Baffling you with the wrong information? There is NO POLARITY in an AC system and there is no "pressure" side in AC or DC. This guy is wholly unqualified to be making videos on electrical system testing or understanding. Ugh.