Electrical – HF compresser pops gfci on different circuit

electricalgfci

Guys I have an almost new HF oil fairly large 15 amp compressor. I have it on a 20 amp circuit in garage with no gfci that I added myself.

From almost day after warranty expired on startup it started pop a gfci on another garage circuit. This circuit has a freezer plus outlets in living room with home entertainment center.

I'm sure there's an issue with the compressor but it works great so currently I only turn it on when needed and then reset the gfci on the other circuit..

Any ideas on how to stop this for happening if he then replacing the compressor or removing the gfci? The gfci has been replaced a couple of times so that not the issue.

Yes it is a Harbor Freight compressor item 61489 r120v/60Hz/15 Amp. It only has 5 hours so not due for first oil change. So no haven't changed it yet. Believe its due after first 10.

The GFCI pops on startup. I can even reset while compressor is running and it stays on fine. Remember the freezer is on the GFCI circuit and compressor is on a non GFCI circuit.

The circuit I ran actually has 3 outlets and a switch. Sorry I forgot. I looked at the circuit and all wired correctly. When I installed it I added a new 20 amp breaker. Black to breaker white and ground to different places on bus bar but both on same side of bus bar. (There is another one on other side left that only has white. Right side has grounds and white.)

So if both circuits white and ground are on same bus in panel could that cause the over lap? Do I need to switch them to the left side bus?

And thanks for all your input! I did have an electrician come look at it and charged me $300 with no resolution. Lol. But they didn't seem to think there was anything wrong with my installed circuit.

I've also wired 2 different 220 volt circuits for a welder and a table saw.

Best Answer

Neutral or ground for the compressor circuit is somehow tangled up with neutral or ground from the freezer circuit. Go through both circuits and make sure of several things:

  • the neutrals from both circuits are totally separated. No contact whatsoever.
  • on both circuits, Neutral is not contacting ground anywhere.
  • the ground wires for each circuit goes all the way back to the panel.
  • there are no "islanded grounds", i.e. Where some devices are grounded only to each other but there is no grounding path back to the panel. Sometimes when people add wiring to old pre-ground circuits, there's a ground wire in the cable so they hook it up. Never do that unless there is a ground path back to the panel. This ground can be retrofit if need be.

Keep in mind ground paths can be things other than wires, e.g. If the compressor is physically touching the freezer.

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