Why does my sump pump keep tripping the GFCI?

A ground fault circuit interrupter compares the current going out on a circuit with the current coming back. The U.S. Consumer Product Safety Commission explains it this way: "If the current flowing through the circuit differs by a small amount from that returning, the GFCI quickly switches off power to that circuit." It also says "The GFCI interrupts power faster than a blink of an eye to prevent a lethal dose of electricity."

So a GFCI outlet trip points to leakage. An ordinary breaker in the panel is the part that trips on overload. That distinction points you toward the cause: something in the outlet, the cord or the pump is letting current escape.

Pump makers want the GFCI there. Wayne's sump pump manual says "FOR ADDED SAFETY the receptacle must be protected with a ground fault circuit interrupter (GFCI)." It also says "All wiring must be performed by a qualified licensed electrician and comply with the National Electric Code and all applicable local codes and ordinances."

Wayne's troubleshooting chart lists the "Pump trips GFCI" symptom with exactly two possible causes: "Bad GFCI" and "Bad pump." Its remedies are "Contact an electrician to replace GFCI" and "Replace pump." Here's what each looks like in practice.

A worn or faulty GFCI. Wayne lists a bad GFCI first, and its maintenance notes put it this way: "In damp areas, GFCI breakers may trip, effectively shutting off the sump pump." If the outlet trips with the pump unplugged, or won't reset at all, the outlet or its wiring is the problem.

A failing pump. When water or wear gets into a pump's motor or cord, current can leak to ground, which is exactly what a GFCI watches for. Liberty Pumps warns that unprotected power and switch cords "can allow water to wick through ends into pump or switch housings, causing surroundings to become energized." Physical damage to the cord does the same thing. Liberty also cautions against lifting or carrying a pump by its cord, because that "will damage the power cord, and could expose the electrically live wires inside the power cord."

Circuit problems. If what trips is the breaker in the panel rather than the GFCI outlet, look at the circuit. Liberty's troubleshooting table lists these causes for repeated tripping: "Circuit protection underrated," "Other appliance on same circuit," a pump "connected to an extension cord or wiring is inadequate or compromised," improper voltage, an obstruction in the pump, foreign matter buildup and a defective motor. Liberty's fix for a shared circuit is blunt: "Pump requires separate circuit."

Stay out of standing water while you check. Liberty's manual says "Do not handle or unplug the pump with wet hands, when standing on damp surface, or in water unless wearing Personal Protective Equipment." If the floor is wet, shut off the circuit at the panel before touching anything.

1. 1Test the outlet by itself. Unplug the pump. CPSC's test for a receptacle GFCI: plug in a nightlight or lamp, press TEST, and the RESET button should pop out and the light should go out. Press RESET to restore power. If the RESET button does not pop out, CPSC says the GFCI is defective and should be replaced. It also recommends testing every GFCI "once a month."
2. 2Watch when it trips. Trips with nothing plugged in point to the outlet or wiring. Trips only when the pump is plugged in or starts point to the pump.
3. 3Look at the cord. A cut, crushed or swollen cord, or one that has sat in water at the plug end, is a reason to stop using the pump.
4. 4Note the pump's age and behavior. A pump that also hums, runs hot or struggles to move water is showing wear on more than one front. See why a sump pump won't turn on and why a sump pump runs constantly for those symptoms.

If the outlet tests fine and it still trips the moment the pump runs, Wayne's chart gives you the answer: the pump.

A tripping GFCI is inconvenient, and people try shortcuts. These are the ones pump makers rule out:

• Don't cut off or bypass the ground prong. Wayne's manual says "NEVER REMOVE THE GROUND PRONG," and Liberty says "Do not bypass grounding wires or remove ground prong from attachment plugs."
• Don't run the pump on an extension cord. Liberty says "Do not use an extension cord to power the product," because extension cords can overload the product and the cord's supply wires, and overloaded wires can get hot enough to catch fire.
• Don't swap in a plain outlet to stop the trips. Wayne's manual calls for GFCI protection on the receptacle. Removing it hides a leak of current into a wet pit. Outlet and circuit changes are an electrician's call.
• Don't keep resetting and walking away. Every trip is a stretch of time with no pump.

That last point is why a high-water alarm makes sense on any pit you depend on. Liberty's pump manual says "If an alarm is used, it must be connected to a separate electrical circuit," so a trip on the pump circuit doesn't silence the warning. Our page on what to do when a sump pump alarm goes off explains the sounds and first checks, and whether you need a battery backup covers the other safety net.

### Set the power up right after the fix

Once the bad part is replaced, the circuit matters as much as the pump. Liberty's manual says its pump "requires a separate, properly fused and grounded branch circuit, sized for the voltage and amperage requirements of the pump, as noted on the nameplate." It also says that for below-grade installations the power supply "shall be at least 4 ft (1.22 m) above floor level," which keeps the outlet out of reach of a flooded floor. Check the pump's nameplate and manual for your model, since each maker sets its own requirements. A dedicated, dry, GFCI-protected outlet at the right height removes most of the reasons a good pump trips.

Split it the way Wayne's chart does. A bad GFCI outlet, a shared circuit or wiring trouble is work for a licensed electrician. A worn pump, a damaged cord that can't be replaced to the maker's spec, a stuck check valve or a pit that needs rework is plumbing. Our guide to maintaining and testing a sump pump helps you catch the next problem early.

HQ Plumbing & Air is a licensed and insured plumbing company with 24/7 emergency service. Estimates are free and the price is set up front. If the pit is filling while the outlet keeps tripping, keep people and pets away from the water and call.