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I have a receptacle that has 3 white wires and 1 black. The black wire is hot and 2 of the white wires are hot but on a separate circuit than the black one (2 bedroom's outlets on separate circuits but tied to this one receptacle). This doesn't seem right to me. All 3 white wires are hooked up to the white side of the receptacle while the black is on the hot side. It takes 2 breakers to turn off the entire outlet (I was shocked when I found out). Really, I was shocked, that's how I found out. I thought I had shutoff the breaker but didn't know the white wires were hot and part of another circuit. It appears I should bracket the two breakers for safety. My real question is "Is it o.k. for the two white wires to be hot and hooked to the white side of the receptacle?". Additionally, when this outlet is apart the second circuit does not work. The whole setup just seems odd. As a side note, the house was built in '63. Maybe different regulations then.

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This is an example of why you always should have a non-contact voltage detector, and use it basically every time before you touch any wires, even when you "know" they are off. –  gregmac Jun 4 '12 at 13:29
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3 Answers 3

Is it OK? No. Aside from the dangerous confusion you experienced there is an ongoing safety problem here. You have hots from two circuits going into one receptacle, but you only have one neutral. By placing load from two circuits onto one neutral wire, you have the risk of overloading that wire without tripping the circuit breakers for either circuit.

It's possible to safely have two circuits feeding one receptacle, if you have a hot/neutral pair for each segment. Additionally, current code requires dipole breakers in this case, so overload on either circuit shuts off both.

To fix this, you need to determine which hot is associated with the same cable back to your circuit breaker as your effective neutral, and disconnect the other hot. (One of the black wires may be feeding another receptacle; make sure that receptacle has a correct neutral.) You should also trace the cables to adjacent receptacles/junctions and check those -- this isn't a good sign about the quality of electrical work in your home. If you're lucky, the fix is just a matter of a few changes in receptacle boxes. If you're unlucky... well, it's better to find out through inspection than through a fire.

You'll want to get a non-contact voltage tester. Be safe!

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It could be a multi-wire branch circuit. I wonder if it is in a kitchen.. –  Steven Jun 3 '12 at 19:50
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Your description doesn't seem right to me. If two white wires are hot, and one is a neutral, then there should be a short where the three wires are wired together, and a breaker would be constantly tripping. So something else is going on here.

The first thing I'd look for is to see if the knockout tab on the outlet is present or not. http://i.stack.imgur.com/l0wTY.jpg

If it isn't there, the receptacle is a split. There should be two hots, and a (shared)neutral on the other side. Typically, this is accomplished with 14/3 wire, Black and Red (or blue) being hots, to separate breakers, and White being the shared neutral. Green or bare copper is ground.

I'm wondering if the whites are two hots, and the black is being used as neutral in this case. (Which means you are going to confuse the next person who opens that box.) This is usually a symptom of Leftoveritis -- The tendency of a DIYer to use improper wire just because they have a leftover coil of it in the basement.

The other white could be used to carry power over to another circuit or switch.

I'd get an outlet tester, and make sure that the outlet is indeed wired correctly (in an electrical sense). If it is, put it back together and write in magic marker "WARNING: WHITE AND BLACK MAY BE HOT" or other such cautionary message.

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If you get the wires sorted out tape the hot white wires with black tape to identify them as hot wires. Do this on both ends.

It's possible someone had a 240V receptacle installed at one time which requires two hot wires on different phases in a residence. in addition there are duplex receptacles available which have a 120V and a 240V receptacle on the same yoke.

In any case this is not a good situation because the wires are not the proper color.

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