NCRUBI2012

Before I connect the main wires can someone tell me if I am okay with this setup or if I am missing anything......please.
Blue Sea 6 Fuse Box loaded with 30 amp fuses - probably never use all of them
6 gauge power and ground wire
100 amp fuse between battery and fuse box
Plan to only use for lights/CB. Do I need relays between swtich and fuse box?

jnabird333

You absolutely did miss something... 6awg is only rated for 50A. Your main fuse should not be larger than this. If you want a main fuse of 100A you need 1/O wire. If you were to pull more then 50A for an extended time, or even 95A for a short time, you are likely going to melt the wire and catch your rig on fire.

jnabird333

This is a general statement on amperage ratings... There are 2/4 awg wires that are rated at 100A but you need to check the temp ratings on the jacket. These types of wire usually have an extremely small stranding. If your stranding is course I would assume the lower current ratings.

tommyluv78

^^^exactly what he said.

NCRUBI2012

And this is why I asked. So 1/o wire for 100 amp. Does the ground wire need to be that as well or just the main power? Do I need relays between this and switches?

jnabird333

Usually circuit protection and power distribution in cars is only done on the positive side of things. This is because the ground (negative) connections are usually made by a good chassis connection near the accessory. If you are planning on running all your negative wires back to the box then yes, you will need a 1/O wire or combination of wires with equivalent capacity for the negative too.

You will likely still need relays for many of your accessories. This is because most switches are only rated for 10A or less.

demp

This is important. Many car audio wires will have higher ratings as they have high thread counts and more wire under the insulation. I've seen people using welding cable as well with high stranding and high heat tolerance. Heat tolerance will be important as the engine compartment is going to get extremely hot as well.

I would lean towards safety and go with bigger wire or smaller load on that 4 gauge. If you do overload a wire you risk heat buildup added to the engine compartment's heat making the insulation fail.

You want your ground to be equivalent to the power cable going in to a device, as the power has to travel through the ground just as it would through the power wire. Consider the circuit is a loop because your battery will be grounded to the chassis as well. Circuit protection is on the positive side as it motivates the flow of current, pulling it from the ground. When a fault occurs it breaks the current inducing voltage from the non charged everything else.