Voltage loss problem. - Electrician Talk - Professional Electrical Contractors Forum

winright007 · 09-11-2009, 08:03 PM

I am trying to figure out why I lose 110v to a line when I turn the breaker on.

It is a 220v underground feed for a barn. One phase is used for lighting, the other phase is used for receptacles. When you turn the switch on for the lights, the 110v drops off. When the lights are turned back off, the 110v returns. It is not a problem with the lighting, I switched the phases to double check. It works the same way if I were to plug in a drill and turn it on.

What would cause 110v to disappear like this? No breakers trip, I simply lose the voltage. When I test each phase, I am getting 122.8 on the good line, but only 108.5 on the phase I am having problems with. As soon as I try to utilize the problem line, my meter will read no voltage at all.

leland · 09-11-2009, 08:17 PM

Measuring line to where? Ground,neutral, line to line?

winright007 · 09-11-2009, 08:21 PM

Line to neutral.

MDShunk · 09-11-2009, 08:22 PM

Sure sounds like you have a marginal hot that's going open under load. Pretty common occurance on farms.

drsparky · 09-11-2009, 08:22 PM

Bad connection, get out the meger.

leland · 09-11-2009, 08:26 PM

Quote:

Originally Posted by MDShunk

Sure sounds like you have a marginal hot that's going open under load. Pretty common occurance on farms.

3rd that

winright007 · 09-11-2009, 08:31 PM

I just talked to the owner after posting this. He told me the line was dug into and repaired. He said it was a long time ago when this happened. He also said they heat shrinked the wires.

So if they did not moisture protect the wires enough, I assume this is my problem. I guess my best bet will be to run a whole new line. There is now an addition on the house, and sits on top of where the wires were ran. It would be almost impossible for me to find the damaged area.

MDShunk · 09-11-2009, 09:47 PM

Quote:

Originally Posted by winright007

I just talked to the owner after posting this. He told me the line was dug into and repaired. He said it was a long time ago when this happened. He also said they heat shrinked the wires.

So if they did not moisture protect the wires enough, I assume this is my problem. I guess my best bet will be to run a whole new line. There is now an addition on the house, and sits on top of where the wires were ran. It would be almost impossible for me to find the damaged area.

That pretty well clears it up then, doesn't it?

Either that old repair failed or a new break developed. Add that to the list of reasons to do all your underground in pipe. Running direct burial under an addition is industrial-strength stupid.

480sparky · 09-11-2009, 09:51 PM

Quote:

Originally Posted by winright007

I just talked to the owner after posting this. He told me the line was dug into and repaired. He said it was a long time ago when this happened. He also said they heat shrinked the wires.

So if they did not moisture protect the wires enough, I assume this is my problem. I guess my best bet will be to run a whole new line. There is now an addition on the house, and sits on top of where the wires were ran. It would be almost impossible for me to find the damaged area.

Is the line a direct-buried cable?

They do make locators that will find the fault in pretty short order.

winright007 · 09-12-2009, 04:40 PM

They ran it in PVC, but hit it with an auger.

480sparky · 09-12-2009, 04:55 PM

Quote:

Originally Posted by winright007

They ran it in PVC, but hit it with an auger.

I guess you don't need a locator, then.

winright007 · 09-12-2009, 05:06 PM

This was done years ago. I am just going to replace the line.

idontknow · 09-12-2009, 11:37 PM

Next time you troubleshoot it, try this.

Utilize the problem line
Check voltage on opposite phase to neutral

If 240, you may have a lost neutral.