Pump breaker immediately trips even with pump switch off

spidey07

Platinum Supporter
LifeTime Supporter
Jun 1, 2012
277
Louisville, KY
Never had the breaker trip before. A 220v/20a GFCI breaker in house panel goes to a junction box outside near pump with a switch in the box. This j-box is then hard wired to WhisperFlo 1hp pump. The key here is the junction box has a switch used to turn pump on or off, just like a light switch.

The breaker tripped and would not reset, I hear a hard click when I move breaker to ON position as it trips immediately. I turned off the j-box switch and breaker does the same thing. Can I assume it's not the pump and there's a problem between the breaker and the junction box (moisture, water, etc) if it trips with the switch off? The pump is rather old but impeller spins freely. I can't see how the pump would cause this if I have that j-box switch off, I use that switch all the time to turn pump on and off. Never had the breaker trip.

Thanks in advance

-edit- I forgot to add there is a mechanical electrical timer (high voltage one with a clock dial and stops that move a switch) between the breaker and that junction box. If I turn timer off the break of course stays on making me think the breaker is OK.
 

Jimrahbe

Mod Squad
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Jul 7, 2014
22,224
Bedford, TX
07,

I also would be looking for a GFCI issue, such as moisture at one of the connection points..

I would just start disconnecting things.. until the GFCI no longer pops..

Thanks,

Jim R.
 

spidey07

Platinum Supporter
LifeTime Supporter
Jun 1, 2012
277
Louisville, KY
Thanks, I wanted to know if I should frantically try to get a pump installed for a party this weekend or just wait and see if things dry out. Could the pump cause this? I guess only way to know for sure is unwire the pump. Which I figured I was doing with the switch.
 

jimmythegreek

TFP Expert
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In The Industry
Aug 10, 2017
3,761
Morris Cnty NJ
If you turn the timer off and breaker stays on the short is in the timer junction box or the timer itself is hard shorted. It's not gonna fix itself or be safe even if moisture present. Open it up if you handy and want to try tackling this or get someone out to look at it. With good pics and leg work we can help steer you in right direction
 

spidey07

Platinum Supporter
LifeTime Supporter
Jun 1, 2012
277
Louisville, KY
Thanks for the help. I guess whatever water causing the ground fault dried up (my guess). Breaker is holding and pump running. We did have some bad storms yesterday but I’ve never had trouble with this circuit.
 

Richard320

TFP Expert
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Jan 6, 2010
23,933
San Dimas, CA (LA County)
Remember, the GFCI doesn't trip because of an overload, necessarily. It detects an imbalance in the current. Something as simple as some water bridging a hot terminal and the case could do it. Milliamps. Miniscule compared to the amp-capacity of the circuit breaker portion.
 

jimmythegreek

TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
3,761
Morris Cnty NJ
this is true, but you dont want water in your electrical enclosures no matter what the cause. its 5 milliamps on most GFCI devices and it looks to the nuetral leg comparing it to the hot leg
 
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