Sprinkler System Trips GFCI After 5 Minutes: Electrical Troubleshooting

Why Your Irrigation Controller Keeps Tripping

A sprinkler system runs for exactly 5 minutes, then shuts down everything in the garage. After 20 minutes and a reset, it runs another 5 minutes. An extension cord to a house outlet works fine. An electrician found no electrical system issues; the sprinkler contractor suspects the timer.

Three Likely Culprits

1. Faulty GFCI outlet: The garage outlet (with test/reset buttons) may be failing under the pump's inductive load.
2. Bad controller transformer: The internal 24V transformer may be overheating and drawing excess current.
3. Failed timer/controller: Internal short or component failure in the controller itself.

Diagnostic Steps

Test by plugging the controller into a known-good GFCI outlet inside the house. If it runs a full cycle, the garage GFCI is the problem. Replace the GFCI outlet first—it's the least expensive fix. If the problem persists, replace the controller.