Puzzling electrical problem in 5’er

[harris71]

I did test the camper on a different circuit in the house with a fairly new GFCI, so that should rule out the receptacle itself. The shopvac is three-prong and have been using this in my garage for years without issue. After unplugging the fridge, I tried the shopvac in the camper and it worked fine.

[twindman]

A gfci isn't that expensive. Go to hardware store and buy a new one to replace the one in the garage. That would rule that out.

[BB_TX]

Is your fridge on a GFCI outlet in the trailer? If so, it is odd that it would not also trip that outlet.

As I mentioned in a previous post, a GFCI outlet wired downstream of another GFCI outlet can cause the upstream GFCI outlet to trip when the downstream GFCI outlet does a self test. Don’t really know much about how or when the self test works. But if the self test is only performed when there is something drawing current from it, then it could be that when you turn on the fridge, it initiates a self test and trips the upstream outlet.

Something to consider.