Aux Fuse Box Wiring Question

I'm installing an aux fuse box and breaker switch tomorrow. I have two quick questions:

1) is it ok to use a different gauge wire (8 gauge) for the positive and neg connections to the breaker and aux fuse box. (e.g. Truck battery cables look like 4 or 2 gauge). Is it ok to mix wire size?

2) my accessory lights already have a fuse in the wiring harness. Do I remove that fuse from the wiring harness and put in the aux fuse box, leave fuse in the wiring harness, but not add a fuse to the aux fuse box, or have two fuses (1 in the wiring harness and 1 in the aux fuse box)?

Your assistance would be greatly appreciated. TIA.

 

you can mix size of wires, as long as its bigger then the load you need.

I generally redo light wiring when i do new fuse boxes. you can keep both fuses, or not, but i would keep them at least on the new aux box vs on the wire somewhere.

 

Thanks; I wired everything up today. Used 12 gauge wire. Striped a bolt for the bracket. Need to clean things up tomorrow, but everything works!

 

Is that 12ga from the battery to the breaker? I would think that wire might fry before that breaker tripped.... I used 4ga form the battery to the breaker and the breaker to the Blue Sea box.

 

Yes; 12 ga from the battery to the breaker. That's my worry... don't want it to catch fire. I have a 4 gauge cable I could attach from the battery to the breaker. Could I use the 12 gauge from the breaker to the fuse box?

 

12ga wire will handle 25 amps - assuming your blue sea breaker is 80 amps you could easily melt that wire and cause a fire before that breaker would trip. Personally, I would not run 12ga from the battery to the breaker OR from the breaker to the box.

The purpose of the breaker is to protect the wire. Using a wire with less than the half the amp rating of your breaker offers no protection for the wire. Conversely, a 4ga wire is rated at 85 amps - so the breaker would trip before the wire would be at risk.

I am by no means an expert. I did a ton of research when building mine and erred on overkill. All my fuse box wires to my relays are 10ga. I used 12ga for my accessories back to the box since nothing has a draw of more than 25 amps. For my switches I used 18ga - the amp draw is minimal there so minimal risk.

I suppose you could use a 12ga from the breaker to the box but I believe that would limit your fuse size to 25amps for anything you were connecting to the box.

 

seeing that you are using a breaker, you need to match the wire size of that or larger. under size will allow that wire to burn up

 

Re-wired with 4 gauge wire today. Thank for the advice.

 

Re-wired with 4 gauge wire

 

Purpose of the fuse box is to organize the fuses scattered around in different wire runs so you don't havet to hunt them down. You'll be eliminating those and replacing them with fuses in the box. The positive wire to the breaker and on to the box as well as the wire from the ground buss back to the battery neg clamp should all meet or exceed the box rating and the breaker should match or at least not exceed the box rating. You want the breaker to trip before either the wire or the box fails.