I have a GFCI in the garage. There are several outlets downstream of it, most of which are outside, with covers on. Despite the covers, sometimes the rain can get in and trip the GFCI. Strangely enough, this pattern only happens in the summer. It rains in the winter too, so why is my GFCI not tripping when it rains heavily in the winter?
The circuit normally has two fridges connected directly to the GFCI, and a computer downstream, and nothing else. In the summer, once it trips for whatever reason, even removing everything else from the circuit, it will still trip afterwards. This is how I found that moisture could get into the outlets outside. Yes, fridges work hard in the summer, but the GFCI still trips with nothing on the circuit.
Note: The coil on the fridge (hot part) is facing the GFCI about a foot away.
I get that fridge compressors can trip the GFCI. I get the moisture tripping the GFCI with nothing else on the circuit. But why is the summer season a factor?
Edit Aug16 2020: I found the source of the tripping. I found a mystery box on a wall with a blank plate and a vertical PVC pipe running into the ground. The pipe had broken, allowing rainwater to get in. Although the wiring is insulated, there might be a knick in the romex further down, or some underground junction. It is possible that the heat difference between outside/underground caused some condensation to form somewhere bad. I prevented large droplets from being able to get in the gap, and the tripping has largely stopped.
I was also confused by the color of the visible wiring, as the sun caused the yellow wiring jacket, used elsewhere on the garage circuit, had faded and appeared white, making me think it was an unrelated circuit.