Why is my shop light occasionally not working?

[cybasmith]

I have a unique problem which a licensed electrician could not solve. I have a 110 sub panel in my small shop for the garage and shop. It feeds off the main panel in the house and has been there for 30+ years and operating OK. Within the last year or so occasionally the lights in the garage would strobe when turned on. I called an electrician who couldn't find any problem and threw up his hands.
Now yesterday the florescent light in the shop wouldn't work. I cycled the breaker and it started working but then quit. When I checked it with my meter it only read 56 volts AC at the breaker. Just as an afterthought I went into the attached garage and turned on those lights and they strobed! When I checked their breaker (single pole) it was reading 56 also! The other three in the panel showed 110. I went to Lowe's and replaced the breaker for the shop light and it worked fine. Later I went into the shop AND NO LIGHT! It was late so I went to bed but in the morning the shop light was on and the breaker read 110. I cycled the light and it would not turn on and measured the voltage and it was 56.
Any clue?
Thanks, Ernest Smith

 

[James]

I think you need an electrician that knows what they are doing.

there is a faulty part somewhere, it needs a logical mind and process to find it.

 

[cybasmith]

I think you need an electrician that knows what they are doing.

there is a faulty part somewhere, it needs a logical mind and process to find it.

That doesn't surprise me, but it doesn't help me find the problem either.

 

[DPG]

That doesn't surprise me, but it doesn't help me find the problem either.

It's probably going to be difficult to find a fault like that over the internet. Needs someone on site with test equipment and a methodical approach to fault finding.

 

[cybasmith]

It's probably going to be difficult to find a fault like that over the internet. Needs someone on site with test equipment and a methodical approach to fault finding.

OK, I'll try again. Just don't know where to go. It's an interesting problem in that the breakers are attached to the same bus bar which has 110 on it but exhibit different "out" voltages! Guess cutting all voltage to the sub panel and then cleaning the bus bar and rearranging the breakers many reveal a solution but I was hoping to head that whole process off. Thanks.

 

[DPG]

OK, I'll try again. Just don't know where to go. It's an interesting problem in that the breakers are attached to the same bus bar which has 110 on it but exhibit different "out" voltages! Guess cutting all voltage to the sub panel and then cleaning the bus bar and rearranging the breakers many reveal a solution but I was hoping to head that whole process off. Thanks.

Decent 'dead' testing would be the way to start here. Before doing live tests. With a suitable test meter.

 

[Timbo]

It's probably going to be difficult to find a fault like that over the internet. Needs someone on site with test equipment and a methodical approach to fault finding.

Bit far for most of us on here to travel! ?

 

[rapparee]

OK, I'll try again. Just don't know where to go. It's an interesting problem in that the breakers are attached to the same bus bar which has 110 on it but exhibit different "out" voltages! Guess cutting all voltage to the sub panel and then cleaning the bus bar and rearranging the breakers many reveal a solution but I was hoping to head that whole process off. Thanks.

Sounds like a broken neutral somewhere.

Are you testing between Live and Earth or Live and Neutral

And is it at the same neutral point in the Distribution board for the 3 "good" circuits as the other "bad" circuit

I'm not sure of the layout of USA - Canada Distribution boards

 

[cybasmith]

Sounds like a broken neutral somewhere.

Are you testing between Live and Earth or Live and Neutral

And is it at the same neutral point in the Distribution board for the 3 "good" circuits as the other "bad" circuit

I'm not sure of the layout of USA - Canada Distribution boards

Thank you for replying. It's a simple 5 breaker 110 box and the live circuits of course go through the single pole breaker. The neutral comes off a bus bar and I didn't think to check the tightness of their connection screws! But sure will now. Don't know how I could have ignored that. Hope it's as simple as that. Thanks.