Is a GFCI required for a outdoor receptacle intended for a vehicle block heater. In a non residential location(Lumber yard). Do you know what is causing the GFCI'S to trip? Bad block heater the Cord?
yes -- outside = GFCI (NEC)
yes -- non-residential (NEC & OSHA)
tripping varies:
1 non-WR GFCI affected by weather
2 cords run over too many times.
3 vehicle backs into receptacle
4 block heaters.
I recommend using GFCI receptacles rather than receptacles protected by GFCI-CBs
I recommend you follow the code and use covers that are rated in-use (cover closes when plug is in)
My experience: 100 or so school buses