miswired receptacles

[Ponchik]

I was asked what is the hazard if receptacle has the hot and the neutral reversed? And I did not know what the answer is.

The only thing that I could think of and I vaguely remember this from 20 years ago that the neutral of some dvd players were connected to the case of the player.

Other than it is required per NEC, that I could not come up with a good reason or at least a reason that the customer would understand.

Your help is appreciated.

 

[Little Bill]

I was asked what is the hazard if receptacle has the hot and the neutral reversed? And I did not know what the answer is.

The only thing that I could think of and I vaguely remember this from 20 years ago that the neutral of some dvd players were connected to the case of the player.

Other than it is required per NEC, that I could not come up with a good reason or at least a reason that the customer would understand.

Your help is appreciated.

I can picture a lamp plugged in to such a receptacle. The shell of the socket would be hot and the "hot tab" of the socket would be the neutral point. Also, if someone decided to "bootleg" a ground from the neutral on a reversed wired receptacle (and they didn't pay attention to the colors of the screw terminals) you would be putting voltage directly on the ground and anything metal it was attached to. This would only be the case if they only had two-wire circuits and tried to get a ground from the neutral.

 

[iwire]

The issue is with screw shell lamp sockets. Reverse polarity to a screw shell lamp will often lead to exposed live parts.

 

[goldstar]

Along the same lines and in addition to what others have mentioned appliances are designed to switch the hot leg internally (just as a wall switch would do). Reversing polarity at the receptacle would cause these appliances (TV's, toasters, blenders, etc.) to continually have a live potential present as long as the cord is plugged in. By the same token appliance cords have been designed to have their plugs made with one blade larger than the other so that they will always be plugged into a receptacle the same way all the time. The manufacturers have done their job to insure proper orientation so the assumption is that we will do ours and wire the receptacles properly.

 

[Little Bill]

I can picture a lamp plugged in to such a receptacle. The shell of the socket would be hot and the "hot tab" of the socket would be the neutral point.

The issue is with screw shell lamp sockets. Reverse polarity to a screw shell lamp will often lead to exposed live parts.

Is there an echo in here?

 

[Dennis Alwon]

I thought some TV's had to have the correct polarity-- not sure what happens if it is reverse polarity-- lamps will work but can be dangerous as mentioned twice but I am not sure about electronic things such as TV's and computers. I don't think it will affect a computer

 

[Little Bill]

I thought some TV's had to have the correct polarity-- not sure what happens if it is reverse polarity-- lamps will work but can be dangerous as mentioned twice but I am not sure about electronic things such as TV's and computers. I don't think it will affect a computer

I don't think it would bother newer TVs or computers either as they have power supplies. I could be wrong.

 

[Ponchik]

Thank you guys.

 

[n1ist]

Older tube radios (and some TVs) often had one side of the AC line tied to the chassis. The chassis was insulated from the user by non-conducting knobs and mounting screws in the middle of rubber feet. If the feet dry-rotted off or you were servicing them, you had to be very careful or use an isolation transformer.

At that time, the TV antenna connections were 300-ohm twinlead with a transformer input, so they were safe.

/mike

 

[electrofelon]

Is there an echo in here?

Yeah sorry, the guy in the server room just informed me that the receptacle feeding the server was miswired causing some hiccups on the forum software......

 

[handy10]

The issue is with screw shell lamp sockets. Reverse polarity to a screw shell lamp will often lead to exposed live parts.

The live shell of the lamp socket is indeed a problem. However, not all lamps have polarized plugs; in fact, it is hard to find a replacement plug that is polarized.

 

[iwire]

The live shell of the lamp socket is indeed a problem. However, not all lamps have polarized plugs; in fact, it is hard to find a replacement plug that is polarized.

All UL listed lamps with screw shell lamps have polarized plugs.

As far as replacements you need to shop better.

 

[iwire]

You should ask for a NEMA 1-15P polarized.

http://www.amazon.com/Leviton-Straight-Residential-Polarized-Non-Grounding/dp/B000FPAN84