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Mike, Master Electrician
Category: Electrical
Satisfied Customers: 2742
Experience:  Licensed Master Electrician - OnQ Certified Data Voice Audio Video Installer
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Why does my GFCI outlet keep tripping after rains?

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My GFCI trips during/after rain storms. Why?

Where is this GFI located? Outside? Is it the one on the screen porch? Or is the receptacle on the screen porch a standard receptacle that loses power when the GFI trips?

Customer: replied 7 years ago.
The GFI is in the garage. There are normal receptacles in the garage, front open porch, and screened back porch on this circuit which lose power when GFI is tripped. There is a small freezer in garage plugged into regular outlet on this circuit. I am not sure if the sump pump under the house is also on it.

And does the GFI still trip even with the items you mentioned that you unplugged, unplugged? Or did you just mean that you have since (after GFI tripped) unplugged those outside devices/equipment?

Customer: replied 7 years ago.

The GFI still trips. I just remembered that there is a dusk-to-dawn light with motion sensor outside the back porch which I had not unplugged yet. A couple questions - can moisture in the air get intoa socket, causing this? or is it more likely an appliance problem?

If you have everything unplugged from this circuit and the GFI is still tripping, which appears to be the case, that rules out that problem (plugged in equipment). Keep in mind though that even if a piece of equipment that IS plugged in is causing the GFI to trip when it rains, that may not necessarily mean the equipment is faulty. It's most likely that water or moisture is getting down inside the equipment which is causing the GFI to trip, which leads to my next point, and most likely the cause of your problem. Moisture in the air shouldn't cause the GFI to trip, but moisture inside the receptacle box would, and that's what I suspect is going on in your situation.

I'd suggest opening up any outside receptacle boxes, and taking a good look inside to see if you see any signs of water entering the box. Outside receptacles, especially receptacles that do not have adequate protection or cover from falling rain are prone to leakage because the gaskets that seal the cover to the wall fail over time. That's why I always silicone mine!

If you have equipment that is plugged into an exposed outside receptacle and you do not have an "In-Use" cover on that receptacle, that is a good point of entry to get into the receptacle when it rains. In previous versions of the National Electric Code (NEC), it was not required to use "In-Use" covers exposed receptacles. Current codes now DO require these covers. The difference is that In-Use covers provide protection receptacle while it is "in use", or in other words, while there is a cord plugged into a receptacle. Standard weather proof covers expose the receptacle to the elements when the cover is opened to plug in a device.

In-Use Cover:

Standard Weatherproof Cover:

Because you have so many receptacles on this circuit, it may make tracking down the problem difficult, but I'd be willing to be the problem is in one of the outlets outside. Feel free to post back any additional questions if you need more help.

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