Outlet Wiring Mystery: 3 hot wires...?

[WillemV]

Hi y'all!

I am positively stumped right now. Lemme explain.

I am replacing old outlets at my in-laws. Their house, built in 1970, got flooded during the horrific TX winter spell. Painters sprayed over everything and drywallers seemed to have had mud to spare.

I got all but one bedroom outlet done, but this one scared the bejeezus out of me. I usually check which wire is the incoming hot, before I turn off the breaker. Well, it turned out on this one three out of the four wires are hot. The two black wires and the two white wires were all on the right terminals. The terminal connectors/jumpers were intact.

With the outlet removed, the two black wires and one of the white wires all trigger the tester. I cross checked the voltages and they come up as follows:

Right now, all wires are disconnected and I have the three hot wires capped. That also killed the power in the adjacent bathroom and the hallway lights.

I used a tracker before I opened the outlet and found the 15 Amp breaker it is on (left leg), which is the one that also has that bathroom and hallway on it. However, the tracker also consistently lights up on a 20 Amp breaker on the right leg. That 20 Amp breaker consistently lit up the tracker with several other breakers on the left leg as well. Not sure if this is related.

What could be going on here? Is there anything I can do to fix this?

Any insight is much appreciated!

Cheers!

- Willem

 

[James]

The fault is likely at another outlet or light switch, probably on the other end of w2 wire, it has become disconnected allowing the voltage to float.

 

[Lucien Nunes]

What device are you using to measure the voltage? If a multimeter, note that the high input resistance can allow a full voltage reading without a solid connection to hot or neutral but via loads, leakage etc.

The permutation of readings is odd, I agree, but there are multiple possible scenarios. Can you get a set of readings from both hots to ground and both neutrals to ground? Can you repeat that with all other breakers off? This should help confirm whether two circuits have got cross connected in some way.

 

[WillemV]

First off, DIY here. I had originally posted this in the DIY area, but an admin moved it to this one.

Beyond my immediate grasp, but it was apparently all wired correctly. I hope I can properly explain...

I use a receptacle tester on all the outlets on the same breaker (bathroom and bedroom). Up to this point they had all shown to be wired correctly. They now (problematic outlet removed) all showed "Hot/Grnd Reverse," with the orange light pulsing every 2 seconds.

Connecting the two neutral wires (W1 and W2) together solved it. That also removed the power from one of the two black wires. So, I installed the new outlet exactly the same way the old one had been. The tester now shows all outlets as correctly wired.

I had a friend over who knows a lot more about electric than I do. He did exactly what Lucien is asking for (readings to ground) and concluded that disconnecting W1 and W2 had interrupted the neutral circuit, killing the bathroom loop and leaving the outlets with a floating neutral.

Interesting lesson learned.

I would still love to understand how a "floating neutral" causes power to show up in other wires.

Thanks!

- Willem

 

[Lucien Nunes]

Disconnecting the neutrals from one another will leave the downstream neutrals floating, but because the hots are also disconnected those should be floating too and neither is likely to show much of a voltage to ground. A floating wire is free to take up any potential it wants, and if multiple runs of NM (Romex) lie side by side, some energised, some floating, then the capacitance between the two can raise the potential of the floating ones towards hot. But usually it will not rise beyond half of the line voltage, often much less, and is just a very tiny capacitively coupled current flowing in that gives a measurable potential to a high-resistance instrument like a multimeter (which in the UK electricians call a 'ghost voltage', not sure if that term is used in the US).

You seemed to have a situation where there was voltage on the downstream (Bathroom) neutral (hence W1-W2 = 115V) and also passing through the bathroom lighting load to energise its hot wire (hence W1-B2 = 111V). This is very near to full line voltage so it does not look like capacitive leakage, it suggests that either:

a) One or more fixture(s) taking a hot from between the panel and this outlet are returning neutral current to the bathroom-side of this outlet, or
b) Fixture(s) on another circuit are passing return current into the neutral of this circuit instead of their own.

a) Would be confirmed by turning off the breaker of this circuit and seeing that all voltages disappeared from both hots and neutrals.
b) Is called a borrowed or shared neutral and it is a code violation for various reasons. One is that isolating only one of the circuits at its breaker and then accessing that circuit can bring you into contact with a live conductor unexpectedly. Another is that some or all of the total current of two circuits can flow down one neutral which might not have sufficient ampacity.

A shared neutral could also be the reason that the tracer indicated multiple breakers when you were originally testing. Reconnecting the whites in the outlet will have restored normal operation, but personally I would like to prove conclusively, where that voltage was coming from while separated. One method would be to separate them again, connect the meter W2-Gnd and then turn off the other breakers one by one until the voltage disappears. Then trace the neutral of the other circuit to find where they meet, or which fixtures are on the wrong neutral if they don't meet.

 

[WillemV]

Thanks for this explanation. This weekend I will check to see which scenario might fit.

 

[Petej999]

Hi y'all!

I am positively stumped right now. Lemme explain.

I am replacing old outlets at my in-laws. Their house, built in 1970, got flooded during the horrific TX winter spell. Painters sprayed over everything and drywallers seemed to have had mud to spare.

I got all but one bedroom outlet done, but this one scared the bejeezus out of me. I usually check which wire is the incoming hot, before I turn off the breaker. Well, it turned out on this one three out of the four wires are hot. The two black wires and the two white wires were all on the right terminals. The terminal connectors/jumpers were intact.

With the outlet removed, the two black wires and one of the white wires all trigger the tester. I cross checked the voltages and they come up as follows:


View attachment 98529

Right now, all wires are disconnected and I have the three hot wires capped. That also killed the power in the adjacent bathroom and the hallway lights.

I used a tracker before I opened the outlet and found the 15 Amp breaker it is on (left leg), which is the one that also has that bathroom and hallway on it. However, the tracker also consistently lights up on a 20 Amp breaker on the right leg. That 20 Amp breaker consistently lit up the tracker with several other breakers on the left leg as well. Not sure if this is related.

What could be going on here? Is there anything I can do to fix this?

Any insight is much appreciated!

Cheers!

- Willem

Is the circuit wired in the form of a RING??????