JK-Ford

Relays are useful for keeping "High Current" devices outside of the cab. They are also useful for keeping the distribution circuits as short as posible. In turn, shorter circuits cost less money, are easier to maintain and are safer.

Conductor and fuse selection is based soley on the connected load. The relationship between these three factors should stay as tight as possible ( with the "LOAD" being the key factor ). You can upsize the wire if you want ( or if necessary based on distance ). But you should never upsize the fuse. If you add aditional "LOAD" to a circuit, you will most likely have to upsize the fuse and the wiring ( basically building a new circuit ).

It's unnecessary to switch an entire fuse block if you are using it mainly for lighting distribution. You only need to switch ( 1 ) single control circuit from an accessory source. Use the switched circuit to power "ALL" of your lighting switches. Therefore, when the Jeep isn't running and the accessory circuit is OFF, none of your switches will work. The only reason to switch an entire block would be for power distribution to: CB Radios, Inverters, Compressor Control, Extra 12 volt outlets, ect, ect.

08HokieJK

I have a few questions.

1) Is 2 AWG for the main power and ground lines to big? Would 4 AWG work as well for the 75 amp max circuit.
2) Does the main ground wire for the fuse block's negative bus have to go to the battery's negative terminal? Or can it go to the frame. Is one way better than the other?
3) Does anyone know what gauge the stock battery cable is for the positive feeder?

Thank you

JK-Ford

4 awg is fine for 75 Amps.

The best way is to connect the ground wire directly to the battery ground. You could use the frame if you like. But if you do, you need to consider up-gradeing the OE frame ground to handle the additional load.