Outlet: Hot/Neutral reversed and you plug something into it

[JEDI]

What happens?

 

[ElFenix]

a lot of things don't care.

something that does care would burn.

 

[woodie1]

Some devices would be fine, some would probably give you a mild shock if you touched a metal part on them.

 

[JeffreyLebowski]

If it has a ground plug it should be ok. Most devices don't really care which way it is. If It concerns you get a tester at the hardware store, they're $5 and check your outlets. If they are reversed, swap the cables on the outlets (make sure you kill the breaker to the outlet first).

 

[Jittles]

If it has a ground plug it should be ok. Most devices don't really care which way it is. If It concerns you get a tester at the hardware store, they're $5 and check your outlets. If they are reversed, swap the cables on the outlets (make sure you kill the breaker to the outlet first).

Buy a tester, they make them for GFCI outlets also; tells you exactly what is miswired.

So yeah, you reverse wires, plug the tester in, it tells you that you f*cked up and you make it right. That's what happens.

 

[Red Squirrel]

Should not do much but I'd still fix it. Takes 5 minutes depending on how far your screw drivers and breaker panel are. You CAN do it live, but I usually prefer shutting the breaker even for simple jobs.

 

[nutxo]

nm

 

[Colt45]

almost always, nothing.

The only thing it matters for is hot chassis stuff (that isn't insulated), which hasn't been code for... forever.

 

[Modelworks]

The light turns on, or the fan or whatever you plugged in.
AC doesn't care about the sink/source 99.9% of the time.

 

[DrPizza]

If you have a light plugged in and the bulb burns out, then with reversed polarity, it's possible for a finger to contact the metal side of the bulb which would shock you. With correct polarity, you'd have to stick your finger into the bottom of the socket to ever get a shock.

edit: otherwise, I can't think of any other "dangerous" situations.

 

[Jeff7]

almost always, nothing.

The only thing it matters for is hot chassis stuff (that isn't insulated), which hasn't been code for... forever.

That, or if there's some kind of wiring fault that would cause the alleged neutral wire to contact the chassis - and you happened to be grounded at the time. If that happens, you're suddenly a very enticing path for a lot of electrons with travel plans.
Unlikely, but bad if it does happen.

 

[Colt45]

Right, but everything modern should have either an earthed chassis or be double insulated. I guess if hot hits the chassis, and earth isn't wired. that's like two levels of major fail.

 

[randay]

a black hole forms, destroying earth and all mankind with it.

 

[Sea Moose]

if you plug in a sensitive item, ie a computer or tv, you will likely fry the circuit boards. A simple item like a toaster or kettle might work ok,

 

[Colt45]

computers and TVs don't care.

 

[Sea Moose]

computers and TVs don't care.

try it on your pc then. I dare you mr tough guy

 

[Paperdoc]

computers and TVs don't care.

TV's are examples of devices that really DO care - at least, some of them! Both TV's and computers often have real connections to a true Ground through other attached wiring like antenna cables and network LAN cables. Now, many are built with a transformer on the power input that effectively isolates the power supply line from the internals. But some still have the Neutral power supply line connected to circuit "Ground". So those ones would be feeding the Hot line connected to circuit Ground to the real Ground connected externally (say, via your cable system), resulting is a heavy current. This might well be heavy enough to trip the breaker supplying the wall outlet as a normal "short" would. But if the connection to the external Ground is not up to carrying that much current, the breaker will not be tripped and a moderate to heavy current will be flowing though that light-weight conduction path, causing drastic overheating and damage. As others have said, during this time the circuit Ground is actually Hot, and any exposed portion of the chassis (for example, the outer screw sleeve of the antenna cable) could be a source of a shock if touched.

If you have a suspect wiring situation, either get someone who knows the system to investigate and fix if necessary, or do it yourself it you are that knowledgeable person. Get a circuit checker and, if there is a wrong connection, turn off the breaker and repair the problem. Then verify that your fix actually did eliminate all the troubles.

 

[AlienCraft]

Old two prong devices are the ones to watch out for for this type of fault.
Also, miswired light fixtures in homes can be wired wrong (i.e. switch on the Neutral leg instead of the hot) and corrupt the wiring scheme.
Old guitar amps are the most likely to still have a 2 prong plug. This is why they came with a "POLARITY" switch that one would switch to eliminate "hum".

 

[Acanthus]

a black hole forms, destroying earth and all mankind with it.

this.

Ever wonder why electricians are paid so well for such a simple job?

 

[AlienCraft]

TV's are examples of devices that really DO care - at least, some of them! Both TV's and computers often have real connections to a true Ground through other attached wiring like antenna cables and network LAN cables. Now, many are built with a transformer on the power input that effectively isolates the power supply line from the internals. But some still have the Neutral power supply line connected to circuit "Ground". So those ones would be feeding the Hot line connected to circuit Ground to the real Ground connected externally (say, via your cable system), resulting is a heavy current. This might well be heavy enough to trip the breaker supplying the wall outlet as a normal "short" would. But if the connection to the external Ground is not up to carrying that much current, the breaker will not be tripped and a moderate to heavy current will be flowing though that light-weight conduction path, causing drastic overheating and damage. As others have said, during this time the circuit Ground is actually Hot, and any exposed portion of the chassis (for example, the outer screw sleeve of the antenna cable) could be a source of a shock if touched.

If you have a suspect wiring situation, either get someone who knows the system to investigate and fix if necessary, or do it yourself it you are that knowledgeable person. Get a circuit checker and, if there is a wrong connection, turn off the breaker and repair the problem. Then verify that your fix actually did eliminate all the troubles.

99% of ALL Electrical systems are Unbalanced, single ended systems. with Ground and Neutral bonded at the service panel. This is why Cable TV Inc insists on BONDING it's equipment with the service ground plane. Most TV only have a two conductor plug and use Chassis Isolation ( Double Insulated) as the Consumer Protection against Electrical system faults. Hot Neutrals are only "wrong" half of the time. Since Ground is bonded, it follows Neutral. This is not a Short Circuit in common home wiring schemes.
In a Balanced AC system ( 2: 60 volt secondarys with a common leg as Neutral With True Earth Ground) A Hot / Neutral Reverse at the outlet will Short the system and Fail on power up.

 

[bobdole369]

if you plug in a sensitive item, ie a computer or tv, you will likely fry the circuit boards. A simple item like a toaster or kettle might work ok,

Wrong.

AC doesn't care about the sink/source 99.9% of the time.

Thats because such a thing doesn't exist in an AC circuit.

What will happen, is that the device will turn on and operate normally.

If you have a really OLD device, where the chassis is not earthed, and what the builders suspect is actually neutral and is connected to chassis, now becomes hot.

Now if you happen to be in bare feet, and you touch that objects chassis, you become a secondary path to ground. Wet feet outside and you might just die.

Nothing built in the past 20 years has this serious of a problem. Even chinese shit isn't built that way anymore.

 

[AlienCraft]

If you have a light plugged in and the bulb burns out, then with reversed polarity, it's possible for a finger to contact the metal side of the bulb which would shock you. With correct polarity, you'd have to stick your finger into the bottom of the socket to ever get a shock.

edit: otherwise, I can't think of any other "dangerous" situations.

An old Fender or Marshall / Vox amplifier, a miswired plug, a Musician with leather soled shoes and a wet stage... oh.... and a video camera to catch the hijinks.
aaahhhh , good times.

 

[Modelworks]

TV's are examples of devices that really DO care - at least, some of them! Both TV's and computers often have real connections to a true Ground through other attached wiring like antenna cables and network LAN cables.

It is illegal to sell such a device.
No tv in the past 20 years has had a way for the B+ ( generated off the flyback transformer, but doesn't isolate using just that alone) and the outer connections to be connected. They are isolated internally on the board, often with very clear markings on the circuit board saying HOT . The power supply for the side where the tuner sits is isolated from the AC current. I worked for GE/RCA in the late 1990's and that was always a chief concern in the design.

The only time I ever heard of someone getting shocked was when an idiot decided he wanted to add a speaker connector to his tv and opened it up and added a speaker connector to the outside. Since the set was not designed to have one that part of the set was not isolated. He plugged in his headphones, and got quite a surprise. Always be careful modifying anything that plugs into AC unless you know absolutely what you are doing. 10 minutes of checking the board area would have told him it was in the HOT section, instead he just cuts speaker wires.


LAN cables are not allowed to carry gnd or any other voltage that is directly connected to a device unless it is POE .
Look at the schematic for proper termination, no direct connections exist.

 

[ktehmok]

An old Fender or Marshall / Vox amplifier, a miswired plug, a Musician with leather soled shoes and a wet stage... oh.... and a video camera to catch the hijinks.
aaahhhh , good times.

Haha, I wish I didn't remember what that feels like.

 

[silverpig]

Another possible issue is with polarized plugs. Someone correct me if I'm wrong, but polarized plugs in say, a toaster, work like so:

PROPER:
HOT-----DEVICE SWITCH------DEVICE LOAD------NEUTRAL

A reversed wiring of the neutral/hot would look like this:

REVERSED:
HOT-------DEVICE LOAD--------SWITCH-------NEUTRAL

Obviously, when the switch is off, no current flows in each case, however if you jam a knife in your toaster in the second case, even when it's not on, you'll get a nice surprise.