Thread: Pond Pump trips GFI. Why?

I was cleaning the filter for the pump in my backyard pond over the weekend and after I got everything put back together plugged the pump back in. It seemed to work fine for a minute or so, then cut out. It had tripped the GFI outlet. I tried again and the same thing happened: worked for a while, then cut out.

Any idea what would cause this? Any idea how to fix it?

My thought was maybe the pump has to work too hard initially because there are air bubbles in the line or something and this is causing the fault.

perhaps the GFI is fried? I've had them "spark out" where they literally melt plastic. How old is the outlet? pop in a new one and see if the fixes it.

jason

Check the pump with another outlet. You might have a bad outlet.

Make sure you reassembled everything correctly with the pump. You might have put it together incorrectly.

Check your wiring from the outlet to the pump. You might have a short somewhere in the line.

You might have a bad pump motor if none of the above led to the solution.

Air bubbles aren't the problem.

I actually tried hooking it up to another outlet with an extension cord and it tripped that circuit, too. The motor was running fine before, so I suspect the problem could be a short in pump wiring. Kinda strange it worked for a while each time before conking out.

yeah - it sounds like you've got some bad wiring that is overloading the amps allowed. how much is a new pump VS. trying to figure out the wiring?

Make sure all the screws nuts and bolts are back in correctly. A lot of times they can be part of a chassis ground especially on a submersible pump.

Don't know if you did, but never pull a pump by pulling on the cord. I have a separate cord attached to the housing. Pulling on the cord can cause a short, and the problem you are having.

Make sure the impeller is spinning freely. Too much strain on the pump will trip the GFI.

How much head pressure are you trying to pump against? Is the line clear? Did you change the out flow?

Maybe time for a new pump.
Make sure the pum is clear, and not plugged up, which will put too much load on the pump, and trip the GFI.

If the pump is tripping the breaker then the load (amps) is too high. If it's tripping the GFI then there's current leakage to ground. A GFI outlet or breaker measures the current between HOT (the black wire) and ground. If the pump's wired incorrectly or if water is getting into the electric bits then the GFI (that's Ground Fault Interuptor) will trip.

Originally Posted by Snow Dog

If the pump is tripping the breaker then the load (amps) is too high. If it's tripping the GFI then there's current leakage to ground. A GFI outlet or breaker measures the current between HOT (the black wire) and ground. If the pump's wired incorrectly or if water is getting into the electric bits then the GFI (that's Ground Fault Interuptor) will trip.

Actually, it reads between hot and neutral. That is why I have them installed at every outlet in my house. In a two wire(non grounded, or old) system, you can meet code by putting gfcis in. Otherwise every outlet needs to be two wire, or you need to put those cheesy 3 wire converters on every outlet.

A GFCI is designed to trip between 4-6 milliamps- for your safety. It will sting, but not kill. The circuitry reads the amperage out against the amperage back in- in a complete circuit. If there is no ground fault- leak of amperage to ground- then the gfci will not trip. Once there is more than 4-6 ma of leakage, it will trip.


In the case of a motor load, there is an acceptable amount of leakage that occurs. Usually when the motor is hot. A good example is a hair dryer. As they heat up, they usually trip the built in GFCI. That is why the manufacturers have them installed on the cord end, cause if they trip a GFCI that is located far away, it is a real PITA to keep resetting it.

As far as a fix, go for the cheaper fix first. Change out the GFCI. They do not all have the same tolerances. By design, some have a larger trip threshhold. It will just be dumb luck, though. Otherwise, I would look over the motor and make sure it is working right. Maybe put an amp meter to the water while the pump is running. There might be some leakage.

Did the pump ever run without tripping the GFCI, or is this a new pump?
Is the GFCI located close to the pump or is there a long run of cord?
If the GFCI is outside, does it have an in-use cover that keeps moisture out, or is it semi exposed? Humidity will kill them really quickly. Weathertight in-use covers will keep them running

Originally Posted by warthog

Did the pump ever run without tripping the GFCI, or is this a new pump?
Is the GFCI located close to the pump or is there a long run of cord?
If the GFCI is outside, does it have an in-use cover that keeps moisture out, or is it semi exposed? Humidity will kill them really quickly. Weathertight in-use covers will keep them running

Yes, it's been running nearly constantly for the two years I've owned the house and presumably is the original pump (probably five years old or so). Until now it has never tripped the GFCI.

The pump is pretty close to the outlet. It probably has a 10-12' cord attached, but it's the pump's normal cord. I don't have it attached to an extension cord or anything like that. The outlet has a weatherproof cover over it. Actually that outlet does not have the GFCI, anyway. The GFCI is on another outlet on that circuit which is inside the house.

I already tried it using an extension cord and a different circuit, so I know the problem is with the pump and not the GFCI.

The thing that confuses me is it seems like if the wiring had a short the GFCI would trip immediately. Instead the pump seems to run fine for a while, then cuts out. It's sort of like you mentioned with a hair dryer: it doesn't cut out until it heats up. The pump is only working against maybe a 5' head difference and it should be plenty big to handle the load. Like I said, it's worked fine for years. I haven't changed anything other than cleaning the filter.

If nothing is forcing the pump to work any harder, then it has probably reached the end of the road. Get a bigger sealed pump.

You are right- if there were leakage, it would trip immediately.


I would say it is a case of designed obsolescence. Pump makers gotta sell pumps.

You could always hard wire it with a kill switch. As long as there is no cord exposed above ground, you meet code.