I recently attempted to reduce the noise and vibration from a bathroom vent fan by putting small pieces of a rubber sheet between the fan's C clamp and the mounting box. Not long afterwards, when I turned off the fan a nearby GFCI outlet tripped. But the fan is not downstream of the outlet -- the fan still worked even while the outlet was tripped.
How can a device trip a GFCI when it's not downstream?
Is it a bad idea to leave the rubber in place? Could it cause problems since the fan would no longer be grounded to its mounting box? The fan is plugged into a standard two-prong outlet in the mounting box.
-Apr