A breaker that trips the moment the pump starts usually means a short: a failed wire splice down the well, damaged cable, shorted motor windings or a failed capacitor. One that trips after several minutes points to a motor overheating or straining. Reset once; if it trips again, leave it off, because repeated resets can ruin a motor.
Key points
- Instant trip: suspect a short in the splice, cable, motor or capacitor.
- Delayed trip: suspect overheating, a stuck check valve or low voltage.
- One reset only. Repeated resets can burn out a repairable motor.
- An insulation test from the surface tells whether the fault is in the well.
Wellborne traces breaker trips on well pumps across Suffolk and the surrounding area. A tripping breaker is the circuit protecting itself, and the useful question is what it is protecting itself from.
Notice when it trips
Immediately on start. The breaker trips the instant the pressure switch calls the pump. That points to a short circuit somewhere between the panel and the motor: a wire splice down the well that has let water in, cable damaged when the pump was last pulled, motor windings that have broken down, or a shorted capacitor in the control box.
After a few minutes of running. The pump starts, runs, and then the breaker drops. That points to a motor drawing more current than it should over time: overheating, straining against a stuck check valve or a partly blocked pipe, running on low voltage, or a pump with a seized bearing working harder and harder.
Only sometimes. Intermittent trips often come from a splice or cable that shorts only when it shifts or heats up, or from a breaker weakened by years of trips.
Why repeated resets are a bad idea
Each reset sends full starting current into whatever is wrong. If the motor windings are starting to break down, repeated starts finish them off. If a splice is arcing, repeated resets can damage the cable further. One reset is reasonable. If it trips again, leave the breaker off. A motor that might have been saved with a new splice can be destroyed by a dozen resets.
How the fault is found
The diagnosis works from the surface down:
- Voltage and the breaker. Is the supply steady at both legs, and is the breaker itself sound?
- The control box. On three-wire pumps, the start capacitor, run capacitor and relay are tested. A shorted capacitor trips the breaker exactly like a shorted motor.
- Insulation resistance. A megohm meter on the pump leads, from the surface, measures how well the motor windings and the cable are insulated from ground. A low reading means the fault is down the well.
- Winding resistance. Resistance readings on each motor lead show whether a winding has shorted or opened.
Those readings tell us whether the problem can be fixed above ground or the pump has to come up.
Lightning and surges
In Hampton Roads summers, thunderstorms are a frequent cause. A nearby strike can surge through the power line or the well’s long cable and damage capacitors, switches or the motor’s insulation. After a storm, a pump that trips its breaker should be tested before it is reset repeatedly. A lightning arrester at the control box or panel reduces the risk next time.
When the fault is down the well
If the insulation test points into the well, the pump is pulled. The cable and the splice just above the submersible pump are inspected first; a failed splice is a common and relatively cheap fix. If the motor windings have failed, the motor or the whole pump is replaced, sized to the well. On deep Suffolk wells, where 59% of owners in a Virginia Tech extension clinic reported depths over 300 feet, the pull is the bigger part of the job, so replacing worn pipe and splices while everything is out makes sense.
What you can safely check
With the breaker off, look for signs of trouble you can see without opening anything: a burned smell at the control box or switch, water around electrical boxes, or damage near the wellhead. Note what the pump was doing before the trip. Then leave the electrical testing to the visit, because the switch and control box carry full line voltage. If you need help, call (757) 919-1972.