Line fault at the outlet -- do I need an electrician?

" So, our house is a mixture of old/DIY and new (renovation); the problem is with the old part of the house."


Hmm, that’s telling eh miller?

Thanks, all.
I ran out of time today, but I'm going to
(a) unplug all things on that chain
(b) measure again to see if the 4v are still there
(c) turn off the breaker and measure everything before (and more) again to see if there's leakage
(d) perhaps take off the breaker cover and see how that breaker is wired — WITHOUT touching anything.

I'll try to report back in case you all are still interested in interpreting.
This is really helpful.

Correction:

jea483,299 posts

03-22-2020
2:57pm


Also as I said previously.

1) VD, (Voltage Drop), on the neutral conductor due to the connected load on the branch circuit.

2) An induced voltage that is/may be created by the hot and neutral current carrying conductors onto the equipment grounding conductor.

4Vac would be pretty high in my opinion though.

"4Vac would be pretty high in my opinion though."

That statement was meant for #2 only.
( An induced voltage that is/may be created by the hot and neutral current carrying conductors onto the equipment grounding conductor. )
It does not apply to #1.

hilde45 OP286 posts

03-22-2020
2:35pm

So, our house is a mixture of old/DIY and new (renovation); the problem is with the old part of the house.

If you would have said the branch circuit wiring you were having the problem with is DIY, I would tell you to hire an electrician to find and fix the problem/s.



Is the wiring in the old part of the house original wiring? Any idea what year that part of the house was built?

Just a guess the branch circuit wiring you have been troubleshooting is 14 gauge. The breaker in the panel is a 15 amp.
Just a guess there is maybe 6 to 8 duplex receptacles on the circuit. At present you have not posted if there are any ceiling light fixtures on the circuit.

By chance do you know what type of wiring the branch is? Is any of it exposed where you can see it? Maybe a back side of an unfinished wall? Maybe in the room the electrical panel is located?
Examples of the type of the branch circuit wiring:
Romex?
Thin wall rigid (EMT) Conduit and wire?
BX? (Wire with an outer flexible interlocked steel armor).

Guys, way to much time has been spent on this thread about the OP measuring a difference of potential, voltage, of 4 volts, from the neutral to the equipment ground contact on the receptacle outlet.
His biggest problem is reversed AC polarity he measured at the outlet. And as he has later posted the same reversed polarity he measured at other outlets on the same branch circuit.

As for the 4 volt the OP measured was it really 4Vac? Who knows.

I just checked a duplex receptacle that is fed by a 20 amp dedicated branch that is used to feed a treadmill. The branch circuit is #12/2 with ground Romex that is about 40ft from the electrical panel at best.

The test:
Multimeter, a Fluke 87. First test, meter set to AC volts. Default range auto scale. Reading,
power switch turned on treadmill only, standby state. Belt not running. Line voltage, 121.5Vac. Neutral to equipment ground, 9.4mv. (Meter allowed to settle down). Note, mv....
(Note Motor in treadmill is DC. That means the power supply is DC. Noise?)

I changed the range setting on the multimeter to 400Vac That is the closest range available above 122Vac.
Line voltage, 121.8Vac. Neutral to equipment ground contact, (after the meter settled down after about 10 sec or so), a steady 0.3Vac.

The above is for one finite test only. A different connected load, and type of load, no doubt would yield different results. No doubt a different, longer branch circuit with different connected loads would make a difference. I could go on and with different scenarios that would, could, make a difference in the neutral to equipment ground difference of potential, voltage.

What really matters? The conductivity, integrity (for a lack of a better word), of the equipment ground to be able to safely carry a ground fault current back to the source and hopefully cause the branch circuit breaker to trip open. (Note. In the event of a bolted ground fault event the instantaneous current could very well exceed 1000 amps.)


Jim
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