Chris, What are you going to run on these circuits that will pull more that 30 amps. A winch or a really large amp. might require such a relay but I would hook them directly to the battery. A winch would also need a master cutoff switch. But an amp needs only a 40 - 50 amp fuse.
Well I have a few items, but basically I just added up all the circuits on the accessory side to get a total amp draw. I will have power windows which will draw quite a few amps plus all the other circuits, which may only draw 10 amps or so but it starts to add up when other ciruits are also on at the same time. Better to put in a relay that should be more than up to the job than to put one in that I will have to keep replacing and eventually rewiring. This way its also got room to expand for the future as I could wire another switched circuit/device off the output of the relay.
