outlet wiring - polarity reversed

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Old 02-23-14, 11:08 PM
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outlet wiring - polarity reversed

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Hello,

I'm new to wiring and looking for some help.

I tested one of my non-GFCI duplex receptacle outlets with a circuit tester and it said the polarity was reversed.

I pulled the outlet out expecting to have to swap the hot and neutral wires but found something more complicated. I removed the outlet and capped the wires except the two black ones in back, which were already capped together. The outlet was originally wired with the two whites, one red, and the ground. (I wish I took a picture of the original...)

The outlet was wired to a light switch (I think the switch activated both the top and bottom.) I tested each wire to see which were hot and attached a picture labeling what I found.

I'd like to know the following.
1.) Why was this wired this way?
2.) How do I correctly hook these wires up to the duplex receptacle?
3.) Is having a hot white wire a code violation?

Thanks in advance!
 
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Old 02-24-14, 03:37 AM
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Welcome to the forums. Switch loop white wires are common, but they need to be remarked as black using a marker or black tape. In your case, however, the constantly hot white is of concern, since your red is switch controlled. What is all the "stuff" in the switch box? Makes diagnosis awfully difficult. Where were the wires located on the original receptacle, in relation to each other? Was the tab broken between the two hot (brass) screws?
 
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Old 02-25-14, 10:11 PM
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The previous owner did some texturing so that's why the cables are a bit obscured. The white and red wires on the left are to the left cable and the black and white on the right are to the right cable.

The tab was NOT broken between the two hot screws. Unfortunately I don't know how it was originally wired to give the reversed polarity...
 
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Old 02-25-14, 10:35 PM
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Turn the circuit off. Connect the two white wires. Turn the circuit back on.
You should measure 120vac between the red wire and the white connection when the switch is on.
You should measure 120vac between the red wire and ground when the switch is on.

If yes..... add a short piece of the same gauge wire to that connection so that you now have three white wires in a wirenut connection. Connect the white wire to a silver screw. Connect the red wire to a gold screw and reconnect ground wire.
 
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Old 03-17-14, 10:44 PM
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This worked! Thanks very much!
I'm curious why when the white wires are connected, and the switch is on, 120V is measured between the white and red (hot) wire. Since they're both 120V, shouldn't the difference between the two measure zero volts? For my education, can someone point me to a circuit diagram that explains this configuration?
 
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Old 03-18-14, 01:00 AM
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You have to look at the broad picture. In the diagram below you see the orange A. That is the white wire connection you had apart. Now look at the orange B. That represents the rest of the circuit which could have lights and receptacles on it. I've shown a light.which was turned on and which would complete a circuit between the black and white wire. Ok..... see that ? The light is actually creating a short across the white and black. If power was on and the circuit was ok.... the light would be lit.

BUT.... you removed the receptacle and opened the white/neutral connection at the orange A. Since the light was creating a short.... the white wire coming back from the light was now also hot. So with those two white wires sitting there apart.... one was the actual neutral connection from the left and the other one from the right was measuring hot.

I could visual this circuit in my head which is why I had you reconnect the whites which repaired the open neutral to the light.

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