Hi,
Looking to add a separate accessory fuse block in the engine bay to avoid cramming my existing stock fuse panel. I included a basic diagram of what I'm looking to do and want to see if this is off-base or somewhat the right idea. Essentially I'm looking to run the proper gauge wire from +/- on the battery to standalone terminal lugs to allow multiple connections. From those lugs, I would feed power and ground to the circuit breaker, power relay and the accessory block (Blue Sea brand style). This would primarily be a switched source panel so from the relay, I would also add a wire to run from the relay to my OEM fuse panel in the accessory spade to tell the relay when to provide power.

For the components, could I use a regular square style spade terminal relay and wire it with either 10/12/14 gauge wire or would I need to go more heavy duty and select a post relay like the PAC-80 style which has the 2 screw lugs for power and 2 smaller screw lugs for the keyed source?

Along with the diagram, I'm also including pics of the relay style I'm referencing and the type of accessory block as well. I'm a novice at this and trying to figure it out as I go along. Trying to see if I'm in the ballpark or off-base with my thought process. Are there other ways that I'm not considering?



Blue Sea Accessory Panel

PAC-80 4-post relay

Wiring Diagram

 

That is pretty much how Olds wired the high current accessories like power windows and seat. The isolation relay only powers those circuits when the ignition is in the RUN position, using a power relay just as you've drawn.

 

Thanks Joe. In your opinion do you think I could use a square 100A relay instead of the type of relay pictured in my original post? Just thinking it would be a cleaner install with one of the cube/square relays.

 

100 amps sounds like waaay overkill for tha,t, and I really don't think you need that monster relay with threaded posts. The Olds isolation relay was 40A for power windows, power tailgate, and power seats (all on one feed). It is extremely unlikely that all those motors will hit stall current at exactly the same time. Just be sure you get a relay rated for continuous duty, not momentary contact. What is the total draw you plan to have on this panel, and are the wires feeding it sized for that current? You can get 40A and even 70A continuous duty relays in the cube package - I would just be sure to use a brand name like Bosch or Hella and not Chinesium. Here's one vendor with an impressive variety of automotive relays.

 

The relay should be rated for 1.25x the amount of the max continuous total load. Wire sizing is based load and length of the run. You don't need to run separate ground wires to each circuit, just use chassis ground or a chassis ground stud if multiple devices are powered in the same location. For the circuit breaker, chances are the only time the main circuit panel breaker will trip is if there is a solid short in the feed wire and a is requirement for a long run and should be sized 1.25x the max continuous load mounted close to the battery. I don't see a need for one if your mounting the panel close to the battery since you have fuses to protect the individual circuits.