I'm having a major issue with my main breaker tripping after running for several hours. I've got a main breaker feeding into UF cable that goes underground to a GFCI subpanel for my pool. At the end of the last pool season, we turned off the subpanel but left the main breaker on. This winter, I found the main breaker had tripped but thought nothing of it. Now that we're opening the pool, I turned on both the main and subpanel, and initially, the pool pump worked fine. However, the main breaker tripped after a few hours, and it wasn't the GFCI for the pool pump that caused the issue. I consulted an electrician who suggested replacing all the breakers, which I did. Everything was running smoothly until it tripped again after 5 hours. When the subpanel is switched off, the main breaker still trips after about 5-8 hours. If the subpanel is on, it tends to trip within 3 hours. I thought that damaged wiring would cause immediate trips but this is puzzling me. The underground wire is about 30 years old but encased in conduit, so I wouldn't expect it to be damaged. Any ideas on what else it could be? Is replacing the underground wire the only option left?
4 Answers
One thing to consider is if the pool pump hasn’t been running, the bearings could be sticking, causing added friction and higher current draw. That could be leading to the breaker tripping.
Have you tried using a current clamp on the line? Sometimes, wiring can be mixed up, causing one circuit to inadvertently feed into another. It might help to see if there’s an unusual current flow somewhere along the line.
Have you checked if the pool pump is drawing more amps than it should? It could be starting to fail, which would explain the breaker tripping. Use an amp meter on the motor to see how it compares to the maximum amps listed on the motor plate.
Just to clarify, are you saying that your main breaker, which isn’t a GFCI, trips even when everything downstream is turned off? That might indicate there’s excess current flowing somewhere. You might want to check your setup again.