Oh yeah on the RV wiring color codes. Inside the living space, electrical codes typically require 120v AND 12v 'appliances' and 'fixtures' to be wired using residential codes:
Black is HOT or POSITIVE
White is NEUTRAL or NEGATIVE
Green (or bare) is GROUND
2 and 3 way (12v and 120v) fridges and overhead lights are often wired this way.
Vehicle 12v chassis wiring is normally:
Black is GROUND or NEGATIVE
Red is HOT or POSITIVE
Green is (usually) ground.
But it is common to have 'blended' codes, such as the radio and fresh water pump and USB ports to have red(+) and black (-) and house battery color codes to have all black cables or black for positive and white for negative, even though its a chassis 12v circuit.
And every roof vent fan I have dealt with always had a black wire for positive and a white wire for negative on the fan, and often the wiring coming in was red and black: You hook up the black fan wire to the red supply wire, and the white fan wire to the black supply wire.
See? Not confusing at all!
