Raindem

We've been in our new house for about 4 months. A couple months ago I noticed something strange going on in my workshop. My 110v compressor started slowing down (RPMs) and eventually it wouldn't work at all. When I turned it on it would just make a few revolutions and then quit. Other electrical tools and fixtures seemed to be working so I figured the compressor was dead. I bought a new one today and plugged it in and it did exactly the same thing. So on a hunch I brought it into the house (separate building) and plugged it in and it worked fine.

Obviously something's up with the electrical circuit in the shop. So I called my builder and he said that all the outlets in the workshop are on GFI circuits and they've had some problems with those choking the circuit. He suggested replacing them with standard outlets. I only had one extra outlet on hand so I replaced one of the GFI outlets. Unfortunately it didn't help, that particular circuit still did the same thing.

I'll call him back tomorrow to say it didn't work. In the meantime, what could cause a compressor to run at like 1/10 its normal RPMs? This is a dinky compressor (and brand new), draws only like 10.5 amps. All the circuit breakers are 20 amps and none of them tripped when I was plugging the compressor into different outlets.

Any ideas?

joe cool

Undersized wire to the shop could result in the compressor seeing less voltage than it needs. What is the distance between circuit breaker and outlet, and what gauge wire between them? If the answer is 100' and #14 that could be the problem.

Raindem

I'm not sure of the gauge, the wiring for the one outlet I did replace looked the same size as any other household wiring. All outlets in the workshop are affected. The closest one I tried was only like 15' from the fuse panel.

JoeD

It originally ran fine so I doubt undersized cable is the problem. More than likely you have a loose connection somewhere on the circuit. It could be in one of the working receptacles.

travelover

Agree, it is most likely a bad connection. Check any outlets with push in connectors by unplugging wires and wrapping them around the outlet terminals (after you flip off the circuit breaker).

Raindem

Thanks for the replies.

To elaborate a little further, it is happening with all the outlets in the shop, which are on 6 different 20 amp circuits. I agree it does sound like a bad connection, or execessive resistance somewhere, but whatever it is is affecting everything.

The builder came by today (nice of him to do that on a Sunday) and couldn't figure it out either. Took the fuse panel cover off and all the connections seem to be tight. We fired up the furnace and the 220V is working OK. So tomorrow he'll be contacting the electrician that wired the shop.

slownsteady

Is there a subpanel involved?

Raindem

Yes there is slownsteady. He (my builder) checked the subpanel and the main panel. But by his own admission he's not an electrician so unless something was just hanging there he may not be able to spot a problem.

joe cool

If your 240V outlets work correctly but your 120V outlets don't you should be taking a good look at the neutral conductor which serves the shop panel.

Raindem

Good suggestion, I bet it's the first thing the electrician does.