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

hilde45 OP288 posts

03-23-2020
11:44am



The reason I’m curious now, as I think I mentioned, is that I’m trying out my audio gear and have been shoved to an inconvenient side of my room because of this polarity problem; so, a fix would be helpful in terms of audio set up.

For this task only.

IF all you want to do is to correct the AC polarity at the outlet you want to plug in the power condition for your audio equipment. Nothing more at this time.....
If you want to do more than that I would suggest you hire an electrician. Better safe than sorry....



From one of my posts above:

Make 100% sure the breaker that feeds the outlet is turned off. Plug a lamp into the outlet. Turn the lamp on. The bulb lights. Go turn off the breaker. The light bulb is no longer lit. Use your mulimeter to verify the outlet is DEAD.

Carefully pull the duplex outlet from the wall box. HOPEFULLY there is only three wires connected to the outlet device.

If more than 3 wires connected to the outlet device,... stop..... Do not proceed.... Draw a picture on a piece of paper showing exactly how the device is now wired noting exactly how and where each colored black and white wires are connected on the outlet device. Make sure to note if the black and white wires are only connected to the side screw terminals. Or maybe also stabbed in the back into quick connect pressure terminals. **Look for any other color wire that may be passing through the outlet box.

Post back you findings.

Note, for the branch circuit wiring:
(Per NEC there shall be only one equipment grounding wire connected to the equipment ground terminal on the duplex receptacle outlet device. All equipment grounding conductors within the outlet box shall be joined/jointed together with a pigtail extended out for connection to the duplex receptacle device.) If the outlet box is metallic, made of steel, the box shall be grounded as well.

Jim.

Thanks, Jim. And I'm not doing anything without rereading these posts and triple checking things are dead. And if I'm even 10% uncertain, I'll just skip it!

But I'm learning a lot and so there's already been a payoff.

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

Not really going the right way.  The voltage appears because you have a resistance on the neutral (bad connection or too thin a conductor) along with current (any other devices on it).

Lets say you use a perfectly good incandescent lamp, and you turn it on, and 4 V appears, off, it goes away.  The lamp is not bad.  The problem is the lamp is passing current (that's how these pesky electric devices work), and the resistance on the neutral is too high. Regardless of the device causing it, your problem is the wiring, not the device.

Best,


E

Hilde45, when you measured the 4 volts while the system was plugged in, were the components in the system turned on, or were they turned off or at least in standby? And as far as you know was anything else that is on the same branch turned on at the time?

If a lot of stuff was turned on at the time it increases the likelihood that the explanations cited by Erik and Jim apply. If not, it increases the likelihood that my hypothesis applies, namely that applying 120 volts to the AC neutral input of the component(s) resulted in excessive AC leakage to ground, mainly via their power transformers. Or, as heaudio123 alluded to, if significant current was being drawn by the components or other things the cause could have been a combination of both factors.

If my hypothesis was the main contributor, though, that issue should go away once the hot and neutral connections are reversed to what they should be.

Best regards,
-- Al

It could also be something as simple as a cracked receptacle causing a leak, I’ve seen some look pretty bad.