Another GFCI Sump thread


Old 03-24-07, 02:42 PM
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Another GFCI Sump thread

I installed an outdoor sump system which is buried in my back yard about 5 years ago. The pump is direct wired to a dedicated 15A GFCI breaker. I installed two indicator lights on the junction box. One simply indicates that power is on. The other light turns on when the pump is running.

Occasionally, the breaker would trip for no apparent reason. I would simply reset it and it might work for several months. Recently, it began tripping immediately any time I reset the breaker.

I suspected a ground fault and set out to troubleshoot the problem. I disconnected the pump at the junction box and used my digital multimeter to measure the resistance from the line and neutral connections to the ground lead. The resistance ranged from 200K ohms to 1.5M ohms depending on which time I measured it. I would have expected to read 30K ohms or less in order to trip the GFCI breaker.

I then reconnected the wiring and tried again to reset the breaker. It tripped immediately. I went back to the junction box and, as an experiment, disconnected the pump ground lead from the service ground wire. I reset the breaker and the pump ran normally without tripping the breaker.

Additional information:

- The sump tank is plastic and buried such that the top is about 12" below the ground.
- The conduit and junction box are non conductive PVC.
- The output piping and all connections to the tank are PVC.
- The sump system is used to remove rainwater from an outdoor patio drain and a french drain as well as residual water that otherwise makes for soggy grass. My back yard has hard pan about 2' down and natural drainage is very slow.
- Replacing the pump requires significant digging and gravel removal to get to and open the top of the sump tank (30 gallon plastic drum).
- At this moment, the tank is open and I have a replacement pump available.

The following URLs are images of the sump system:



1. Is there a safety reason to use a GFCI circuit breaker in this application?
2. Is my existing problem with the breaker tripping likely a problem with the pump or with the breaker?

My current plan is to replace the pump since I already have dug it up. My questions here are to help me in the future with regards to replacing the GFCI breaker if I continue to have problems.
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Old 03-24-07, 03:59 PM
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Keep the GFCI breaker and replace the pump. The old one developed an internal fault. Don't cover things back up until the new one has been running well for a while.
Old 03-24-07, 05:23 PM
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Check all first

Occasionally, the breaker would trip for no apparent reason.##

There is always a reason.

Most likely the pump has some leakage (electrical). Or the light sockets could be corroded.Bypass the lights and see where your at. Pumps are exspensive.
OR the buried wires have a fault. The GFCI breaker protects the conductors (wires) too.
If this continues the breaker can and will go bad aswell.
Old 03-24-07, 07:00 PM
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Thanks for the quick advice. Both the pump I removed and the pump I am installing have labels which recommend using a GFCI circuit breaker.

Regarding the lights, they are sealed plastic LED units which have given me no problems besides the fact that they are nearly impossible to see if they are illuminated during the day.

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