Why Does My Sump Pump Keep Tripping the GFCI

Quick answer

A sump pump tripping the GFCI outlet is usually due to a ground fault, moisture, or a faulty pump motor. Turn off the pump, unplug it, and test the outlet. If the outlet resets but the pump still trips it, the pump motor is likely damaged and needs repair or replacement.

Confirm the symptom

• Sump pump trips the GFCI outlet repeatedly
• Pump works for a while then trips the GFCI
• GFCI outlet trips even when the pump is off

Tools and prep

• Multimeter
• Infrared thermometer
• Shop vacuum or soft brush
• Wire stripper
• GFCI tester
• Rubber gloves

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Prep & safety

• Turn off the sump pump and unplug it from the GFCI outlet
• Ensure the area around the sump pit is dry before starting any tests

Step-by-step troubleshooting

1. Test the GFCI outlet
   Do: Plug a known working device into the GFCI outlet and turn it on. Press the test button on the GFCI outlet to see if it trips.
   Observe: If the outlet trips with a working device, the outlet is faulty.
   Means: The GFCI outlet is defective and needs replacement.
   Next: Replace the GFCI outlet.
2. Test the sump pump motor
   Do: Plug the sump pump into a different GFCI outlet and run it. Observe if it trips the new outlet.
   Observe: If the pump trips the new outlet, the motor is faulty.
   Means: The sump pump motor has a ground fault and needs repair or replacement.
   Next: Replace or repair the sump pump motor.
3. Check for moisture
   Do: Inspect the area around the sump pump and outlet for signs of water or dampness.
   Observe: If there is moisture near the outlet or pump, it can cause the GFCI to trip.
   Means: Moisture is causing the GFCI to trip. Dry the area and ensure proper sealing.
   Next: Dry the area and retest the outlet and pump.
4. Inspect the wiring
   Do: Check the wiring connections to the sump pump and GFCI outlet for any signs of damage or corrosion.
   Observe: Damaged or corroded wires can cause a ground fault.
   Means: The wiring is faulty and needs repair.
   Next: Repair or replace damaged wiring.
5. Test the GFCI outlet with a tester
   Do: Use a GFCI outlet tester to check the outlet for proper function.
   Observe: If the tester indicates a problem, the outlet is faulty.
   Means: The GFCI outlet is not functioning correctly.
   Next: Replace the GFCI outlet.
6. Check the sump pump float switch
   Do: Ensure the float switch is not stuck or damaged.
   Observe: A stuck or damaged float switch can cause the pump to run continuously.
   Means: The float switch is faulty and needs repair or replacement.
   Next: Repair or replace the float switch.
7. Test the sump pump with a multimeter
   Do: Use a multimeter to test the resistance of the sump pump motor.
   Observe: Low resistance indicates a short in the motor.
   Means: The motor has a short and needs replacement.
   Next: Replace the sump pump motor.
8. Check the GFCI circuit breaker
   Do: Locate the GFCI circuit breaker in your electrical panel and test it.
   Observe: If the breaker trips when the pump is running, it may be faulty.
   Means: The GFCI circuit breaker is defective and needs replacement.
   Next: Replace the GFCI circuit breaker.

Common causes

Parts you might need

When replacing parts related to your sump pump and GFCI outlet, ensure the new parts match the specifications of the old ones.

• GFCI outlet: match the amperage and voltage rating of the existing outlet
• Sump pump motor: match the horsepower and voltage of the original motor
• Electrical wire: match the gauge and type (e.g., NM-B) of the existing wire
• Float switch: match the length and connection type of the original switch
• Waterproof cover: ensure it fits the size and type of your outlet box
• Wire connectors: match the size and type (e.g., wire nuts) of the existing connectors
• GFCI circuit breaker: match the amperage and type (e.g., 15A, 20A) of the existing breaker

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Take photos of the old parts and their connections to help with installation.

When to call a professional

• The GFCI outlet continues to trip after replacement
• The sump pump motor shows signs of internal damage or burning
• You are unsure about electrical wiring or circuit breaker replacement
• The problem persists after replacing all suspected parts
• You detect a strong electrical smell or sparks near the outlet or pump

FAQ