This could have been done by a failure in the NEUTRAL Wiring at the PEDESTAL as well...
Something along the way may have got the NEUTRAL BUSS OPENED and out of balance (CAMPGROUND PROBLEM).
This would be a problem at the campground shore power pedestal...
Ideally the AC VOLTAGES around the three or four CAMPGROUND PEDESTAL AC SOCKET CONNECTIONS should read like this when measured with a AC VOLTAGE...
50 AMP SERVICE (Read at PEDESTAL before hooking up)
30/20/15 AMP SERVICE (Read at PEDESTAL before hooking up)
Any readings different than this is cause for concern...
Loose connections on the NEUTRAL BUS BAR inside your 120VAC distribution Panel can also cause this to happen...
TYPICAL WFCO POWER DISTRIBUTION WIRING DIAGRAM
The BLACK lines are HOT going to the circuit breakers.
The GRAY lines NEUTRAL BUS BAR is floating (NOT GROUNDED).
The GREEN lines GROUND BUS BAR is grounded to the RV Frame ground.
The INVERTER shown here is OPTIONAL EQUIPMENT.
Roy Ken
