cornfused!

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Steve McKinney

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Fellas, I have doing this a while, but I have never seen this. Customer complains that every now and then about half of his house goes electrically dead. OK, no big deal.........happens all the time. Probably a bad line connection at the meter or panel. He has had success restoring power by pulling out the main plug in cartridge fuse holder and slamming it back in. OK, that is where it is, right? Trouble is, when it goes dead, sure enough, one side of the line coming into the panel from the meter base is 0 volts in reference to ground. Other side is ok. And of course, line to line is 0 volts. Then we perform the hi-tech slam and the voltage magically appears. 120 to ground and 240 line to line.

I might add that it is a very old install as you can imagine. I expect I will be soon changing out the service, but I am having a time "noodling" this out!

The meter can and the panel are connected with about 7 foot of old SE cable.

Any of you experienced such a head scratcher?

Thnx in advance.

Steve McKinney

"When you're green you grow, when you're ripe, you rot!
 
Change the service tomorrow and be done with it.

When you measuring for voltage exactly what are your volt probes touching?
 
The fuse holder may have a loose screw on one of the stab tabs we had this happen on and old panel we swaped it with one we had until we could change out the service
 
Any of you experienced such a head scratcher?
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Yup.

Many time I have been SURE that a pullout, breaker etc was was making contact.....but it obviously wasn't. If you look closely enough you will eventually figure out why.
 
Were you able to look in the meter socket?

I had a similar situation on my own house. Most of the time, everything was okay. But every now and then, I'd lose half the house. If I turned the main off, and then back on, bingo, power back on. I first assumed it to be the main breaker. But before I replaced it, I called the PoCo to check their equipment. They pulled the meter and one of the line side connections was corroded something terrible.

I replaced the meter socket guts, and everything is fine now.
 
The next time it goes out - if there is a next time - check voltage at all points - pull the meter and do the same, at the POCO side of the weather-head too if there is one.... Would really make you look silly if it is on the POCO side of the service drop after a service change would it not???? I would check thier side first in case pulling the meter jostels it enough to go back on. FYI you could also invest in an IR thermometer - just find the warmest connection while it is still on and under load. A loose arching connection will be hotter than the others...
 
Wow! Thnx for the responses guys. Just now got back on. My voltage probes were on the left ungrounded conductor and the grounded conductor, then right side ungrounded(hot) and the grounded(neutral) conductor. It should read 120 at these points. When it was in "fault" condition, left to neu was 120. Right to neutral was 0. Hot to hot was 0.

Did not pull the meter, I really suspect the problem is there but it is about 7-8 feet from the panel via SE cable.

Will call PoCo and get a free inspection. What ya think?

Thanks guys, your the best.

Steve
 
Steve McKinney said:
My voltage probes were on the left ungrounded conductor and the grounded conductor, then right side ungrounded(hot) and the grounded(neutral) conductor. Steve
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On the wire in the terminal, or on the terminal itself? Line side of main, or load side of main?

In the past I have found terminals that were never tightened an operational for long periods of time. The connection LOOKS OK - but isn't.... The wire feeding it is fine, but the terminal isn't getting anything past the carbonized gap between the conductor, and the set screw of the terminal - jiggle a bit and all is well for a time.... Remove the wire - clean terminal screw and lug and conductor - reinstall, this time tight - good forever... Same thing on just about any termination - or breaker buss...
 
Steve McKinney said:
Any of you experienced such a head scratcher?
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Yeah, have had a rash of them lately, it seems. The last two turned out to be corroded meter socket terminations.
 
probe locations

probe locations

Yes e57, I should have been more specific. I was careful to intentionally check on the wire itself. One of the first things I did was to try and tighten the line screws of the panel.

Just when you think you know this stuff.......................
 
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