My house was built in 1994. The garage is fed from one 20amp circuit wired to the lights first, then a GFCI, then a couple regular outlets. This has worked fine for me for 19+ years.
We had a storm Friday morning, after which the GFCI now trips when anything is turned on (even a power-strip with lighted switch). Garage lights still work (as expected since they are ahead of the GFCI). With the CB off, I put my meter on the receptacles to look for a short, but found none. With CB back on, all receptacles have 120vac available, but the second something that draws even the smallest amount of current is plugged in, the GFCI trips.
I replaced the GFCI with a brand new one, but still have the same problem. I pulled the GFCI out of the wall and put my meter on the screw terminal. Both line and load have 120vac when reset. If I press the test button, the line side drops to 32vac and the load side to 10vac. The garage lights still work fine at full intensity, so the line voltage on the garage circuit isn't dropping.
The only possible explanation I can come up with is that a broken wire (high winds caused the garage structure to shift?) is still making some contact to pass 120vac at no current, but the poor connection is causing the voltage drop with any load and causes the GFCI to trip. The GFCI has a tiny LED that comes on when tripped (off when reset) which must be creating the small current draw.
Anybody else have any thoughts?
I don't relish the though of opening the walls in the garage to run new wire. Perhaps I'll temp one with an extension cord to prove the solution electrically first.