120 Volts between neutral and Ground - Woodworking Talk

TomC · 09-10-2009, 05:13 PM

Any good electricians out there? I have a problem above my knowledge. I had several overhead lights quit working. I went down and checked the main breaker box. No breakers were tripped and I took the cover off. I noticed an arcing about every 30 to 90 seconds on a neutral wire. I turned off power and disconnected the neutral wire. I put power back on the panel and read the voltage from this wire to ground and had 117 Volts. I started turning off breakers one at a time and found one that removed the voltage. It is the circuit that controld the problem overhead lights. I now have disconnected all wires in the light switch box and still have a voltage. Between the hot and neutral for that box I have about 70 volts. I now have 45 volts on the neutral. I think it is time to call a electrician but thought I would see if there is an electrican out there that can tell me what to check.
Tom

rrbrown · 09-10-2009, 05:34 PM

Tom your getting a back feed from something that is shorted. depending on the circuit it could be hard to find. have you done anything new lately, even if it was put a screw in the wall ? You can start by finding everything that is on the circuit and start checking each connection from start to finish. only connect the first thing in line and check it then make the connection to the next thing until you find what is bad. some kind of way the power is jumping from hot to neutral finding it is the hard part .

I had a GFI trip for my daughters bathroom but could not find the GFI. I happen to be looking for something in my wifes closet on the other side of the house and noticed a tripped GFI outlet. It was the problem and I have no idea how that crap passed inspection. we bought the house new 4 years ago.

TomC · 09-11-2009, 11:03 AM

The hot wire for the circuit appears to be putting the voltage on the neutral. I have everything disconnected and have a voltage on the neutral coming from the breaker box. With this voltage I can't start connecting different lights. I believe I need to run a new hot/neutral to the light box. I cut into the wall behind the box (garage side) and there is no damage to the wires. I can seethe wires through a removable ceiling in a basement closet. However, the remainder of the basement has a sheetrock ceiling. I am going to call a licensed electrician as this is a potential fire issue if I am wrong.
Tom

rrbrown · 09-11-2009, 11:43 AM

That might be a good idea. Some things are hard to diagnose without actually being there and testing. If the power is coming from the neutral of a circuit that has the breaker off then it is back feeding from another circuit through a connection somewhere. Let me know what they find.

TomC · 09-11-2009, 02:52 PM

I talked to an electrician this afternoon and he said it sounded like a loose neutral some where in the panel. He said to tighten up all the neutrals and try it again. I tighten all of them and still had 40 volts on the disconnected neutral when the breaker was closed. I open the breaker and reconnected the neutral and closed the breaker; I was expecting arching, bkr tripping or somthing. Nothing happened. I checked in the light switch box upstairs and I had 115 volts between the neutral and hot. I reconnected everthing ( a few lights at a time) and every thing is working. In hind sight my problem more than likely was the loose connection at the arcing neutral and it only needed to be tighten. However, when I disconnected it and had a voltage on it I got side tracked. I still don't understand how a loose (or disconnected) neutral in the box will cause a voltage on a neutral. My only problem now is to patch the sheetrock in the garage. I guess this better than spending who knows what on a licensed electrician. I had rather spend the money on more tools. Maybe this info will help someone with a similiar problem.
Tom