Most RV's have a GFCI in the Bathroom.. Sometimes it is somewhere else and sometimes there are two or more.
GFCI outlets have the ability to not only protect a user using a tool plugged into them, but also additional protection to down-line outlets.. kind of like this.
Breaker---GFCI--Protected 2----Protected 3---Protected 4
Well.. The patio is one of those "Protected #" outlets (I have 5 such Bathroom, other bathroom, Dining table, Kitechen and patio.
You may also have a problem with the tool you plugged in or the cord feeding it. (In which case the GFCI did its job and protected you).
