I want to put an Battery isolater switch so I can cut off anything coming from the battery when the car is not used. I have had some conflicting advice, some say it should be on the red/power cable, other say it should be the Earth. What does the collective think please.
If its just to disconect the battery when not in use, earth cable.
If you want to it following FIA regulations, so its usable as a kill switch, its power cable. You must use a resistor ( suplied with most proper kill switches).
Plus side of option 2, the Kill Switch. It kills all power when in case of emergency. Engine stops, fuel pump stops and no damadge to the alternator.
You can hook a cable system to this so its accecable from the drivers seat.
Imo, do it right, proper FIA compliant kill switch on the power cable.
We are not talking about a Kia whatever, but about a GT40.