Odd home wiring issue - Page 1
Forum section: electronics / general

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: August 06, 2021, 07:23:07 pm
content: Found an outlet in my friend’s house where I measure 120VAC between hot and neutral, 0VAC between hot and ground, and 25VAC between neutral and ground. All measurements tension the same in LowZ mode.He had things working, but got shocked by his electric guitar (when touching another ground).Sounds like some sort of hot / neutral reverse, but what would cause the 25VAC reading neutral to ground rather than a full 120VAC?Any thoughts on the best troubleshooting procedure? I was going to check other outlets on the same branch circuit first. Then check the wiring on the outlet.

author: bdunham7
author_rank: Super Contributor
timestamp: August 06, 2021, 07:36:26 pm
content: Quote from: FlyingHacker on August 06, 2021, 07:23:07 pmHow old is the house? It sounds like the problem is with the ground. Reversing hot/neutral at the socket shouldn't cause an immediate hazard without some other fault somewhere. You probably just need to identify the breaker, shut it off and then pull the outlet out and see what is going on. If no problem found, you need to pull the other outlets on the same circuit.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: August 06, 2021, 07:42:25 pm
content: I believe the house is about 40-50 years old. The issue is in the updated basement area.Ok. I will have a look see.

author: bdunham7
author_rank: Super Contributor
timestamp: August 06, 2021, 07:47:29 pm
content: Quote from: FlyingHacker on August 06, 2021, 07:42:25 pm50 years or less it should be wired with 3-wire NM or NM-B in an updated area, IOW there should be full-sized ground wires. A finished basement may be a non-pro job so there's no telling what might be in there. Is there a subpanel or just one breaker box?Do your friend a favor and consider adding a GFCI to the circuit once you have it figured out.

author: Gregg
author_rank: Super Contributor
timestamp: August 07, 2021, 11:11:39 pm
content: Is there a sub panel for the basement newer electrical installation? If so, the neutral and ground should be separate from each other and only tied together at the main panel. Often there is a screw that threads through the neutral bus to the surrounding metal box and it can be hard to spot. This is supposed to be only used on the first or main panel; never on sub panels.(edit:) Also make sure the ground and neutral are tied together at the main panel and this point should also be connected to a ground rod or other permissible ground.This is just a starting point; obviously there are other problems with some of the neutral returns are returning on the ground or something else has a partial short to ground but not tripping a breaker

author: dropkick
author_rank: Contributor
timestamp: August 13, 2021, 02:21:53 am
content: Also check the outlets themselves. I had a situation in a home on the coast where several outlets were leaking internally due to corrosion from the salt air and age. You mentioned a basement environment, though it sounds like its newer. Must be a "homeowner special" rennovation!

author: ejeffrey
author_rank: Super Contributor
timestamp: August 13, 2021, 03:07:14 pm
content: Definitely sounds like a bad ground connection. Possibly also reversed hot and neutral. I would test on some other outlets the same way and then pull out the outlet to inspect it. Chances are you will at least see evidence of the problem there. Be extra careful, measure everything and if possible shut off the whole panel because if there is a live to ground fault the metal frame of the outlet might be hot.

author: Gregg
author_rank: Super Contributor
timestamp: August 13, 2021, 10:24:44 pm
content: Just today a good friend invited me to lunch and I soon discovered the reason for his hospitality. He had a 3 way lighting circuit that was intermittent. After a few minutes I discovered that it worked if I pushed on one of the light switches I could get the lights to work. Long story short: the cause was whoever wired the house made splices using the multiple back stab wire ports on cheap devices and one was making poor contact. I suspect that many of the receptacles in his house are wired the same way; but I wasn't in the mood to look for trouble.Which brings me to suggest that the OP's problem may be a bad neutral connection somewhere along the problem circuit path. Confirm every connection, line, neutral and ground along that path.