Contactor Blowing GFI

KWiK · 02-20-2012, 10:50 PM

I just finished my control box, plugged it in, turned the switch and blew the GFI. I am down to only having the Contactor wired up as shown in the attachment with nothing attached to the output and nothing else on the neutral connection, and it still blows the GFI when I turn on the switch. Am I wiring the coil wrong or ? There was no wiring instructions with the contactor, but it seems like a 120V coil should just have 120 on one side, and neutral on the other.

Any help appreciated.

**mateomtb** · 02-20-2012, 10:56 PM

I saved this link awhile back, it may or may not help.

See 5th post.

http://www.homebrewtalk.com/f170/dual-120v-electric-biab-276646/

**stellaontap** · 02-20-2012, 11:11 PM

If I understand it correctly you are right..... the hot wire goes to one side of the coil and the neutral goes to the other side.

KWiK · 02-20-2012, 11:33 PM

Thanks Guys.

I just took the contactor completely out and jumper'd the coil to a regular outlet. The contactor sounded like it worked, and I didn't blow the 110 GFI on that circuit.

So does that mean my 220 gfi is bad? I have used it for my welder, and didn't have any trouble, but It only uses 3 of the 4 wires.

**stellaontap** · 02-20-2012, 11:58 PM

Did you a load hooked up when it blew the 220 gfi or was it just energizing the contactor itself?

**P-J** · 02-21-2012, 12:34 AM

Just something to keep in mind. When useing a GFCI breaker for 120V and 240V power. It is critical that the neutral load wiring comes from the GFCI breaker neutral terminal. It must not be wired from the neutral 'input' side of the GFCI breaker.

Failing to do this will result in the instant trip of the GFCI breaker as soon as it sees a 120V load. (As in your case.)

Hope this makes sense.

**cl330b** · 02-21-2012, 02:53 AM

I recently did a project where one side of one of the the coils was wired to 120VAC and the other side to ground. Every time I picked the contactor, the GFCI tripped. I discovered the wiring error, moved the grounded side of the coil to the neutral bus and it works great now. The only way I could see the GFCI tripping is if there is any current, even a small draw (mA) between the hot and ground. Im not saying this is what your issue is but it only takes a moment to verify. Good luck!

KWiK · 02-21-2012, 03:37 AM

It was just the contactor itself that was blowing it.

I think I understand PJ. It seems really unlikely that I would have hooked it up to the input side of the breaker, but I need to do some checking.

I am sure it is the neutral and not ground.

thanks for the replies. I will try to do some more digging into it tomorrow night.

pvtschultz · 02-21-2012, 12:45 PM

I stole this from P-J's site for reference. Make sure that your spa panel is wired like this for three wire dryer plugs. The ground bar won't be connected to neutral bus for a four wire dryer cord.

KWiK · 02-21-2012, 11:58 PM

Thanks Guys. Only had a few minutes to look into it tonight, but I did have the GFI wired wrong. I had the neutral out going to the bus bar instead of the breaker itself. I hooked it back up enough to just check the contactor and it sounded like it worked when I turned on the key.

Hopefully that is the only thing I hooked up wrong.