WiremanWireman · Sump pump not running: troubleshooting for electricians · 2023 NEC ·
Sump pump not running
Test it with water, check the GFCI and outlet, then bypass the float switch briefly.
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How it works
A sump pump is turned on by a float switch: a tethered float that tips up, a vertical float on a rod, or an electronic sensor. Many plug in through a piggyback plug: the float’s plug goes into the wall and the pump plugs into the back of it. Basement receptacles need GFCI protection under current code, so a tripped GFCI is a common cause. The fastest test is to pour water into the pit and watch.
Every question and answer in this guide. Tap “Step by step” to walk through it.
- Pour a bucket of water into the pit until the float rises. What happens?
- Nothing, no soundIs the receptacle live? Check for a tripped GFCI (it may be at another receptacle or a GFCI breaker) and measure the receptacle.
- GFCI was tripped, it holds nowTripped GFCI
- GFCI trips againGround fault in the pump or cord
- Outlet is deadDead receptacle
- Outlet is liveWith water in the pit, unplug the pump from the float’s piggyback plug and plug it straight into the outlet for a few seconds. Does it run?
- Runs when plugged in directlyFailed float switch
- Still deadFailed pump
- Hums, but no water movesJammed impeller or stuck motor
- Runs, but the pit doesn’t emptyDischarge problem
- It runs nonstopStuck float or a failed check valve
- Nothing, no soundIs the receptacle live? Check for a tripped GFCI (it may be at another receptacle or a GFCI breaker) and measure the receptacle.