Pump trips gfci, but only when I turn it off?!?!

SSBrew - 728
Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Dgonza9

Dgonza9

Well-Known Member
Joined
May 20, 2010
Messages
1,182
Reaction score
12
Location
Evanston
My first brew day with the new control panel.

Sometimes, not 100%, when I turn off my pump, it trips the gfci in the main panel.

Turning on does not trip anything, only when I turn it off.

Any ideas? Exhaust fan and keggle elements don't trip anything.

Does the spinning action of the pump create electricity somehow? I have the pumps hard plumbed with copper, if that matters.

I'm running a 30 amp 220V gfci breaker, but using each leg to power 120V elements, pumps, etc.

Appreciate any ideas you may have. Cheers!:mug:
 
If the pumps are not hard-wired but plugged into outlets, I would try to narrow down the problem. Is the trouble with one or multiple pumps? Maybe try the pump in a regular 120V GFCI to see if the trouble follows the pump or stays with the position in the panel. If the problems appears to be with the panel, try a different load besides the normal pump and see what happens. Those tests should quickly eliminate some questions.
 
Due to the inductance of the motor windings, you can get a voltage spike when the current flow is suddenly interupted (when you turn off the pump). I wouldn't expect that to cause a problem with the GFCI unless maybe somehow the high voltage spike is finding a path to earth ground (arcing?). As a test, you might try isolating the pump housing from ground by isolating it from contact with metal (brewstand ?) and by disconnecting the safety ground or using a "cheater" plug (3 prong to 2 prong adapter) if it's plugged into an outlet. I wouldn't recommend using it this way, but it might be a useful test to see if the problem goes away when you do this.
 
there may be an internal defect in the pump. a gfci does nothing more than monitor the current flow to ground. the pump when turning off, is shorting out causing the gfci to trip.

ungrounding the pump is not good advice. did you recently purhase it?
 
Hmmmm... Since the problem is intermittent, it's difficult to trace. About half the time I turn it off it trips the gfci.

All of the receptacles being fed by this circuit breaker share a neutral and a ground. So I imagine the problem stems from the pumps themselves, not the receptacle wiring. I did try plugging the pump into the other pump receptacle and it did trip the breaker.

The exhaust fan is wired to the same bus bar as the pumps and it never trips the gfci.

So I'm thinking that it's the motor induction that causes a spike and that my gfci is somehow overly sensitive to it. But I'm really not sure how to test this theory.
 
I tried the "cheater" plug. It does indeed keep the gfci from tripping.

Any ideas how/why the voltage spike from the induction is finding the ground? How I might fix it?

Should I take apart the receptacle and look for a short? Or is it more likely that the current spike is somehow grounding via the hard plumbing?

Appreciate any help you can give. Thanks.
 
If the grounding was through the hard plumbing, the cheater plug would not have prevented the GFCI tripping.

A couple of things I can think of:
1. You have some ground wiring, inside or outside the pump, that is almost touching line or neutral - not quite close enough to short, but maybe arc over during a high voltage spike. Check your wiring carefully, but if it's in the motor, then I'd think it is defective.
2. Could the pump have gotten water or wort into the motor recently? Some moisture in the wiring might create a high resistance leakage to ground - not enough current to trip the GFCI during normal operation, but maybe enough during a high voltage inductive spike. Let the pump dry thoroughly (several days?).

By the way, what type/brand is the pump? Is it a March pump or other magnetic drive type? Plastic rotor housing, or metal? Is the pump mounted to a metal frame? If so, did you isolate it during the cheater plug test?
 
DeafSmith said:
If the grounding was through the hard plumbing, the cheater plug would not have prevented the GFCI tripping.

A couple of things I can think of:
1. You have some ground wiring, inside or outside the pump, that is almost touching line or neutral - not quite close enough to short, but maybe arc over during a high voltage spike. Check your wiring carefully, but if it's in the motor, then I'd think it is defective.
2. Could the pump have gotten water or wort into the motor recently? Some moisture in the wiring might create a high resistance leakage to ground - not enough current to trip the GFCI during normal operation, but maybe enough during a high voltage inductive spike. Let the pump dry thoroughly (several days?).

By the way, what type/brand is the pump? Is it a March pump or other magnetic drive type? Plastic rotor housing, or metal? Is the pump mounted to a metal frame? If so, did you isolate it during the cheater plug test?
Click to expand...

My panel feeds 8 boxes, each with one receptacle. They share a neutral and a ground. If I plug the pump into the first box and it trips the gfci when I shut it off, does it mean the problem lies between this outlet and the panel ground bar?

I'm also wondering if I don't have a defective/overly sensitive gfci breaker. Possible?
 
Dgonza9 said:
My panel feeds 8 boxes, each with one receptacle. They share a neutral and a ground. If I plug the pump into the first box and it trips the gfci when I shut it off, does it mean the problem lies between this outlet and the panel ground bar?
Click to expand...

If the problem is in your wiring, it could be in any of the boxes. Or it could be the pump motor.

Dgonza9 said:
I'm also wondering if I don't have a defective/overly sensitive gfci breaker. Possible?
Click to expand...

You could try plugging the pump into a 120 volt GFCI plug which plugs into a wall outlet. If you don't have one, you can get one from a hardware store - I think about $12 - $15. That would take your panel completely out of the picture.
 
DeafSmith said:
If the problem is in your wiring, it could be in any of the boxes. Or it could be the pump motor.



You could try plugging the pump into a 120 volt GFCI plug which plugs into a wall outlet. If you don't have one, you can get one from a hardware store - I think about $12 - $15. That would take your panel completely out of the picture.
Click to expand...

I tried it. It doesn't trip the GFCI receptacle on a separate circuit. But the whole point of the panel is to have all the buttons in one place.

I was reading electrical forums and many people complain of a similar problem with exhaust fans in the bathroom tripping the gfci. It has even happened to me a few times in our upstairs bath, but not very often.

I'm going to try disconnecting everything past the first receptacle to see if the problem remains. Maybe I can narrow it down.
 
Okay, I disconnected the ground pigtail from all but the first outlet in the series. I tried the pump in this outlet. after 5-6 tries, it tripped the breaker.

I'll see if I can connect it at the panel to rule out wiring in the conduit from the receptacle boxes to the panel.
 
The problem lies between the panel and the receptacle.

I wired an outlet directly to the switch in the panel and was not able to reproduce the problem. So the ground wire must have gotten damaged in pulling it thru the conduit.

I'm going to run a new one tomorrow and see if this takes care of the issue.
 
Quick update. It appears that used a power strip as an extension cord. When I took that out of the loop the problem disappeared. I'm still running some tests, but it appears to have some surge protection which was causing the issue.
 
Yeah, that might explain it. Power strips with surge suppression use MOV's (Metal Oxide Varistors) which break down to a low resistance when a voltage higher than line voltage is applied. These would be connected, I think, from line to ground and neutral to ground. Everything is fine with normal line voltage, the MOV's are high resistance. Then when you turn off the pump, the inductive voltage spike temporarily breaks down the MOV causing a low resistance path to ground.
 
Yeah, what DeafSmith said. That's a BIG thing that wasn't mentioned early on in the post.... Glad you found the problem - please report back here with the final findings if that did indeed fix the problem!
 
Took the power strip out and everything works fine. No trips.

Thanks for all the help.
 

Similar threads

audioa84
Troubleshooting Custom Brew Controller Breaker Issue - Solved
Replies
7
Views
904
doug293cz
doug293cz
Benson Brewhouse
30A GFCI works with Brewzilla but trips when connected to dryer
Replies
3
Views
3K
mashdar
mashdar
Eaglesbrewer44
Another Electric Panel Build
Replies
35
Views
3K
Eaglesbrewer44
Eaglesbrewer44
ALAN C
Need help to confirm wiring .
Replies
17
Views
2K
ALAN C
ALAN C
westo2
20 gallon eKettle upgrade - what's your preference?
Replies
2
Views
1K
westo2
westo2

Latest posts

Back
Top