Home wiring: is 47V between neutral and ground OK?

No, that is certainly not normal. Check the neutral and ground connections in the panel, as well as anything that uses those horrible spring loaded push-in terminals, those are notorious for developing bad connections, IMO they ought to be banned.

If you are using a digital voltmeter, you could be seeing an open circuit on the ground wire at the fixture. However, that being said, if you have an open neutral at the breaker box or service entrance, you have a serious condition warranting that you call for the utility service or an electrician immediately. Fire and death by electrocution are possibilities. Do any appliances or lights behave as the voltage is too high or too low? If so, you have a serious problem.

If the fixture is working then leave it alone. If the fixture is not working remove it and hook up a rubber pigtail socket and bulb to the ceiling wiring to check it. Stop using your voltmeter. I'm guessing that you are checking the voltage between the neutral with the fixture lit and the grounding conductor.

I concur. Work your way back from the fixture with a voltmeter and see where you lose that 47V.

Story about spring loaded terminals: I helped a friend diagnose a flickering lights problem at his house. It seems that one circuit, heavily loaded was fed through a receptacle using these spring loaded contacts (in one set and out the other). It was the first device on the branch circuit and was easy to diagnose. Although nothing was plugged into it, the device was hot (thermally)!

I just had a circuit go dead in my house the other night, tracked it down to the very same problem. I decided that while I'd already messed up all the clocks finding the right breaker, I'd use that opportunity to shut things down and replace the last few of the original upstairs receptacles I hadn't gotten to yet and in that process I found one more blackened corroded wire that had been arcing and was a failure or fire waiting to happen.

The contact area is simply too small, it heats up and then the spring loses tension and it starts to arc and heat up more. These things are a safety nightmare, I will never understand why the NEC is so nitpicky about some things yet lets major issues like these slide right by. Spend a few bucks more for decent receptacles, it's cheap insurance and peace of mind, not to mention plugs won't start falling out in a few years.

More than a few volts between the neutral and ground indicates that they are not connected together. If they are properly connected together in the entrance panel and the fixture is working, the ground is disconnected somewhere (floating). Use a bulb in a pigtail socket to check this. It should light from hot to neutral and from hot to ground. Be careful as a floating ground can cause dangerous voltages to appear on supposedly grounded metal parts, especially if you connect a load from hot to the ground.

Don Young

Does any device use push ins for ground? I have not seen any (that doesn't mean they don't exist, I'm asking an honest question)

nate

I'm not sure if these things are still available. All I've seen at the local Home Despot are screw terminal types. Either the basic 'wrap the wire around the screw' or the 'stick the straight wire in the hole and apply pressure via an internal screw and clamp'. None depending on a spring alone.

Besides that, I don't like using receptacles for a feed-thru. Pigtails wherever possible, unless the box is too small to contain the extra wires and nuts.

I think this is scary advice. The OP seems a bit out of his depth here. He would be better advised to hire a competent electrician to get to the bottom of this situation. There may be a perfectly rational explanation for the voltage between N and G, but it also is an indication of a truly unsafe condition.

When my son bought his house a few years ago, I found out that the electrical system was upgraded by using grounding receptacles. Some were found in the bathroom. The only problem was that no grounding conductor was present. Everything would work as well as could be expected until you become the grounding conductor. There probably are many such gotchas almost everywhere.

Bill

Worst case is that the test light will illuminate connected from hot to neutral. But it will be dim due to high voltage drop and the person doing the test will not notice. A high resistance connection will get HOT under load and may create a fire hazard. If a hot or neutral is wide open, nothing works, but nothing gets hot.

No, but they do for neutral, and if neutral is floating at all above ground, you'll measure a voltage between them. Of course the light will be dim in that case too.

*Granted. However the OP has failed to post any details. He didn't say if the fixture was working correctly or not. He didn't say how he came to find the voltage discrepancy. He didn't say why he changed the light fixture. I just made some assumptions that everything was working fine and he was just playing around with his volt meter. If the OP cares to furnish more details then perhaps my response will be different

The problem isn't the NEC. The problem is UL allows these atrocities. At least the hole isn't big enough for #12 wire anymore.

If its a DVM then yes you see that often. In fact, I would be more worried if I saw 0 volts between neutral and ground when using a DVM... because that meant that somehow my neutral got grounded and now my ground is a load carrier (a situation you never want to see). Get a low-impedance analog VOM meter and re-test it, you will see a much lower or zero volts. Try a neon tester, it probably wont light. The

47V with a DVM is most likely induction current easily detected by the DVM which has a very high impedance able to detect small current.

That is why I thought that OP was out of his league. Apparently he thought so as well because he hired a presumably competent contractor. I think that showed good sense on a situation that many people would feel falsely competent to handle.

A few years ago, I hired a competent electrician to track down and replace a poorly connected neutral conductor. I had diagnosed the problem but had not pin-pointed where it was. That turned out to have been a good decision because he was experienced in such matters and I was not. I am confident that I could have located the problem but it would take ten times as long and I would not know the best way to correct it.

Bill

Oops I missed the post that the OP found the open ground, but I have seen all kinds of wierd readings on normal wiring if you use a DVM. Also neutral problems scare me more than working on hot leads. Thats because hot leads always simply terminate and their breakers are 1 to

1. So you would have to consiously put your body "in series" with the current flow even if you are dumb enough to not trip the breaker.

Whereas neutrals travel all over the house, so if you open a wire cap on a bundle of neutrals that you find in a box somewhere, even though your breaker is tripped on the circuit you think is correct, that bundle may still have some current flow from a different branch that is live. So if you happen to separate and grab two of those neutrals as you remove the wire cap, your body immediately is put in series with a load carrying wire, not good. Being in series with a neutral carrying 10 amps is instant death.

Neutrals actually require more safety caution than working with specific hot leads especially when unbundling wire caps to insert another pigtail.

Exactly right. I might note that a high impedance voltmeter isn't a good tool here.

That's what GFCIs are for. Place a GFCI upstream of these outlets and all is well. Place stickers on the ungrounded outlets marking them as ungrounded and you're even in compliance. Often, adding the grounded conductor just isn't practical.

obscenities.

I've just re-subscribed to this group. I'm begining to remember why I stopped reading it.

'Shot your wad' is firing blanks, like a starter pistol. There is no projectile, just wadding. Even an ignorant Navy grunt should know that much about weapons.