Puzzling Receptical Question

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  #1  
Old 11-23-05, 09:31 AM
Mike98
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Puzzling Receptical Question

I turned off power to a receptical to replace it. I pulled the receptical out and there are three white (common) wires, Two black and one ground. In my old recepticle, there are holes to plug in two whites and two black at the rear of each of the two recticals (top and bottom totaling eight holes for wires)

I got "bit" because there is still power somewhere. My question is, what is that extra white wire, and how did I get "bit" if I turned the breaker off?

ps- when I pulled the extra white wire out, the ceiling light went out.

Thanks, Mike
 
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  #2  
Old 11-23-05, 09:56 AM
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Join Date: Jan 2004
Location: Oregon
Posts: 1,219
You are lucky that you didn't get killed. You either have what is known as a 'multi-wire branch circuit', or you have what is known as a 'bootleg neutral'. In this sort of circuit, two _separate_ 120V circuits, supplied by two _separate_ breakers, both share the same neutral. If you don't turn off both breakers, then you will see no voltage until you separate the neutral connection, at which point 'bang' you have 120V in your hands.

There are many details required to get a multiwire branch circuit right, and they are much less forgiving if you get them wrong. Do things wrong and you drop 240V across your 120V devices. Additionally, some other aspects of your post suggest to me that you have a 'bootleg neutral', which is essentially a multiwire circuit intentionally done wrong because it is convenient and 'gets the job done'. The fact that the receptacle itself was used as the splice in the multiwire circuit is itself a code violation and as you learned a significant safety hazard.

I suggest that you

1) turn off breakers until there is no voltage at this receptacle.
2) pigtail a new receptacle in. This means that you use a wirenut to connect all of the white wires together with a 6" white wire, all of the blacks to a 6" black, and all of the grounds to a 6" ground, and then connect the 6" wires to the receptacle. Don't use the receptacle to splice wire.
3) read up on multiwire branch circuits, or call an electrician, to investigate this properly.

-Jon
 
  #3  
Old 11-23-05, 10:06 AM
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Join Date: Feb 2002
Location: port chester n y
Posts: 2,117
This MAY be an outlet-box where a 3-wire Branch-Circuit cable that extends from the panel terminates, and the O-B is the connection-point for 2 seperate 2-wire circuits.

The "2nd" 2-wire circuit will have the Black wire connected to the Red wire of the 3-wire B-C cable, which is then implaced "out-of-sight" inside the O-B.

The White wire of the "2nd" circuit connects to all other White wires in the O-B. When you opened the White wire-connections, you opened the "2nd" circuit.

Good Luck & Learn & Enjoy from the Experience!!!!!!!1
 
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