Aux fuse block and relay wiring

Hello electrical experts. I am wiring up an axillary fuse box to handle my accessories (GMRS, Fridge, Jackery, lights, compressor) and I would like to confirm I am doing it right.
I want the aux fuse box to flip on only when the car is running. Is a relay the way to do this? how should I wire relay 86 to accomplish this?

 

You do not need to ground the fuse block but a ground bus is part of the fuse block for your convenience.

Check where your battery + is attached as I think you may be attaching it to the bus terminal and not the supply terminal that will run through your individual fuses.

You will want to trigger your relay with an ignition source. Easiest would be in the under hood fuse box with an add-a-fuse tap. There is good info on an ignition source in the switch pro threads so just check that your relay trigger doesn't require a bunch of current and size the add-a-fuse properly.

 

Yeah on that fuse block, the top terminal (under the yellow clip thing) is the ground side, and the bottom is the positive side

 

Thank you for pointing out the +/- issue, and pointing me in the right direction on the add-a-circuit.
Updated diagram:

 

What you have drawn will work. I would likely take the main ground for the bus straight to the battery since it's so close anyway.

 

Are you also planning to run dedicated relays for some of the heavier loads?

 

Yeah, anything that I want to control with a switch I will add an additional relay for, like my compressor and aux lights.
My GMRS, 2 additional 12v sockets powering my fridge and jackery, and my additional USB charging ports for my dash mounted phone and tablet will go directly to this fuse block. Do you see any issues with this approach?

 

No. Sound approach. Something to consider is using an integrated fused/relay block vs just a fuse block and then a relay block or individual relays. Goal is to minimize wire length runs for high current devices so you can avoid wrestling heavy gauge wire everywhere. Looks like you might already be parts committed though.

 

Oof, yeah parts committed for sure haha. Excellent tip for any future readers of this thread though.

 

Looks good except for the aux fuse block ground, don't connect it to the fuse box mount, you'll get a much better ground connection by going right to the battery negative terminal. You don't "need" to ground the aux fuse block if you aren't bringing your grounds for the devices back there and you can just ground to the frame by the device you're wiring up. Something else to consider to save on a little wiring.

 

Appreciate all the help I got on this thread. Got everything installed and it works as intended. Now to add the accessories.

 

looks great man. ive got a few questions for you though, im thinking of doing a similar set up, what gauge wiring did you run to connect everything ive heard 6 is a good size, but ive also heard of people doing 2. what would be the purpose of going so big?

 

I am not an expert, but I used 6ga.
It's cheaper and easier to move around and I don't think I'll be requiring more than the 55 amps it's rated for.
People might use 2 gauge if they require 115 amps.

 

Which block from this list would have the relays included already? And is there anything else to consider when choosing that method? https://www.bluesea.com/products/category/16/61/Fuse_Blocks/ST_Blade

 

dont think blue sea has a product like that, at least not on that list there.

 

It comes down wire length. This is a handy calculator.

https://www.wirebarn.com/Wire-Calculator-_ep_41.html