Key Takeaways
- Repeated GFCI trips indicate a real ground fault.
- Conduit can carry water far from its entry point.
- Drainage direction matters where exterior conduit enters a building.
- Testing needs to reflect the conditions that trigger the fault.
The Situation
A Costa Mesa restaurant’s outdoor prep area was served by a GFCI-protected circuit that tripped with every rain, even light drizzle. It tested perfectly dry, and two replacement GFCIs had changed nothing.
Initial Assessment
The rain-to-trip pattern was too consistent to blame the device. The weatherproof outlet box and visible fittings looked sound on a dry day, so we expanded the search beyond where rain fell.
The Diagnostic Process
We traced the run from the outdoor outlet to the panel. It entered the building at an upward angle near the roofline, so water entering outside could run inward. A fitting at the outdoor junction box was not fully sealed. Water traveled down the conduit to an interior low-point junction box, where moisture created a small but genuine ground-fault current.
Root Cause
Water entered an improperly sealed fitting and traveled through conduit to an interior junction box. The GFCI was correctly detecting the moisture-caused ground fault, 15 feet from the outlet.
The Solution
We weather-sealed the entry fitting, re-routed the penetration to a downward angle so future moisture could drain out, dried and cleaned the interior box, and added a weep hole at the outdoor low point as an additional precaution.
Results
- No trips through the following rainy season.
- The outdoor prep area remained reliable.
- The repair cost less than the prior replacement attempts.
Lessons Learned
GFCIs trip for a reason. The right response is to locate the ground fault, not replace the protective device. Conduit is a pathway, not a waterproof guarantee; exterior-to-interior runs need thoughtful sealing and drainage.
Frequently Asked Questions
Why does my GFCI keep tripping even after I replace it?
A fault downstream, often moisture or damaged insulation, can remain after a new device is installed.
Can water get inside electrical conduit?
Yes. Water can enter through imperfect fittings and travel through a conduit run.
What is a ground fault and why does it trip a GFCI?
It is unintended current flowing to ground. A GFCI trips when it detects that imbalance.
How do you find a ground fault that only happens sometimes?
Inspect the path and test under triggering conditions, using targeted isolation and monitoring.