Odd Outlet Wiring

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  #1  
Old 04-15-14, 02:58 PM
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Odd Outlet Wiring

Hi, I have an odd outlet that I was trying to replace. This place was built in the 70s and I just wanted to put new outlets and switches in.

I turned off the breaker and tested the top of the outlet to verify it was off. I didn't realize I should've tested the bottom as well, but that's where it gets a little odd. So I pull it out and start removing the wires and see a spark. I grab my meter and find voltage still on the line. I traced it back to another breaker in the panel. So I turn that one off as well and now there is no voltage at the outlet.

I get the outlet removed and find two sets of hot and neutral wiring to the outlet. Ok, I'm cool with that, BUT I notice neither of the tabs are removed on the outlet itself. This seems very wrong to me, but I wanted some opinions on this.

Please give me some input here. If I'm to replace this outlet, should I:
1) Wire it with two sources, but remove the tabs
2) Just cap one source and use the other for the outlet

Neither are controlled by a switch, just right to the breaker.

Thank you for your help!
 
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  #2  
Old 04-15-14, 03:27 PM
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Receptacle

Two cables each having hot, neutral, and ground usually means the receptacle is in midstream with power coming in on one cable and going out to the next receptacle on the other cable. If there are two circuits on two different breakers connected to the same receptacle, something is very wrong.
 
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Old 04-15-14, 03:59 PM
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If both breakers are on the same buss the voltage between the two hots will be 0 so it wouldn't trip a breaker but it is still wrong. The tabs on both sides should be removed.
 
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Old 04-15-14, 04:22 PM
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Ok, so I was correct in thinking this was wrong and also correct thinking both tabs should've been removed. Whew.
Now, since I'm not an expert, would this have meant I had 220v on the outlet? If not, would this circuit have ever tripped one or both of the breakers?
Now I feel the need to hurry on this job replacing all outlets and switches.
 
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Old 04-15-14, 04:28 PM
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You didn't have 240vac on the receptacle. That would have been a short between the two circuits which would have caused a bang.

Do you have one or two neutrals there ?

You have the makings of a multi wire branch circuit. The neutral would be shared and your two breakers would be right above each other and opposite hot legs.

If you have two neutrals then you would remove the neutral tab and the hot tab. If you only have one neutral you will need to do some breaker shuffling.
 
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Old 04-15-14, 05:02 PM
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There are two neutrals and two hots with tabs still intact.
And thank you for clearing up the 240v
 
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Old 04-15-14, 05:06 PM
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Then as long as you are sure they are on two different circuits...... the hot and neutral tabs need to be removed.
 
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Old 04-15-14, 05:08 PM
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As I wrote:
If both breakers are on the same buss the voltage between the two hots will be 0
Verify by measuring the voltage between the two blacks.
 
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Old 04-16-14, 12:43 AM
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Wow, so even weirder now. I removed the outlet and called it a day. Just capped the wire ends for the night so I could turn the breakers back on. Now the outlets in the kitchen don't work. Please explain to me how this could happen with the setup I explained? Essentially I have two breakers tied together on the outlet, but now additional outlets don't work?
 
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Old 04-16-14, 06:55 AM
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Sounding more like a multi wire circuit. Did you make the measurement I requested? What color wire on the two breakers involved?
 
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Old 04-16-14, 07:10 AM
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Two separate circuits on the same yoke are required to have the breaker handles tied, but that isn't possible if both breakers are fed from the same bus. My opinion is this needs to be changed to a proper MWBC with common neutral so that the breaker handles can be tied. In this case, you would only break the tab on the hot side of the receptacle and leave the neutral side tab intact.
 
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Old 04-20-14, 01:07 PM
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Thanks for your responses. I've been on a crazy work schedule this week and haven't had a chance to test the theories yet. Finally off tomorrow and will see what I've got and get back to you.
Also, what is MWBC?
 
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Old 04-20-14, 04:40 PM
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... Wow, so even weirder now. I removed the outlet and called it a day. Just capped the wire ends for the night so I could turn the breakers back on. Now the outlets in the kitchen don't work. ...
Double check. If you turned both breakers in question back on with all the wires loose in the box in question, do the kitchen receptacles come back on?

Double check. With the power on on all breakers and all wires still loose in this box, verify if both cables (their black wires) are live. If both cables are live then (2) cap one source and use the other for the new receptacle.

MWBC -- Multiwire branch circuit. Has two hot wires (with twice the normal lighting and appliance voltage between them) and one shared neutral in the same cable. Usually one of the hots is red. Do not connect both the red and the black of the power cable to the same receptacle except to the two gold colored screws on one side with the tab broken off.

Two cables with just black and white wires each and with both cables live are not treated like an MWBC. Neither their hots nor their neutrals may be interconnected anywhere downstream.
 

Last edited by AllanJ; 04-20-14 at 05:34 PM.
  #14  
Old 04-22-14, 03:27 PM
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<Sigh> So, I think I've found the problem. Looks like the previous owner double tapped on two of the breakers.

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This is what is coming out of the wall.

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Pics of the outlet I cut out showing the tabs still in place.

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There is another breaker on the other side of the box that is also double tapped, but I haven't run into the problem with that yet.

I DID take voltage readings in the kitchen and found 64volts there. I took readings from black to black in the wall and there's 140v there, odd. Black on right to ground is 122v, black on left to ground is 40v, again, odd.

Did I miss any other suggestions or tests to do?

Thanks again!
 
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Old 04-22-14, 04:05 PM
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Double tapped breakers are not a problem unto themselves.

What does count is that any hot wire, after it leaves the breaker and the panel, and any sub branches coming off of it, may not join up elsewhere with a hot wire or sub branches coming off of another or even the same breaker. In other words, from any receptacle or light or other location there must be exactly one path back to the panel., and the neutral must follow the same path, being in the same cable or conduit.

Odd voltages from hot to ground, while hot to neutral is the correct voltage, usually mean a bad connection somewhere in the ground (equipment grounding conductor) path back to the panel.
 
  #16  
Old 04-22-14, 04:16 PM
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That would have been a short between the two circuits which would have caused a bang.
I'm failing to understand any possibility of this receptacle working with its original wiring if there are two sources connected to it.
 
  #17  
Old 04-22-14, 04:20 PM
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If two sources are connected to the same receptacle (without broken tabs) and both sources are from the same side or leg of the 120/240 volt service then things will seemingly work normally.

What is the voltage from black to white (all combinations)?

After measuring that, try this for kicks. Turn off both breakers in question. Connect together the two white wires in the box in question but leave the two blacks loose. Turn on the breakers. Does anything change as to what other receptacles or lights now work or don't work? Do you get different hot to ground and hot to neutral readings?

If both black wires are still hot relative to neutral (white) then disconnect the two white wires when you are donw eith this test.

If a branch circuit or a sub branch of it has a neutral problem, tying into the neutral of a different branch circuit to get around this problem is not proper.
 

Last edited by AllanJ; 04-22-14 at 05:01 PM.
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