Please check my diagram

ESUPPORT Car Auto Heavy Duty Split Charge DC 12V 100A 100 AMP SPST Relay 4 Pin 4P RL180

$12 ESUPPORT Car Auto Heavy Duty Split Charge DC 12V 100A 100 AMP SPST Relay 4 Pin 4P RL180

https://www.amazon.com/dp/B012N09BFE/ref=cm_sw_r_cp_api_i_.52TDbA8K3VNJ

 

Just my 2c as an engineer during the week, code violator on weekends:

I don't see an issue running 100A for future-proofing the circuit, just make sure everything along the way can support 100A continuous. That means (as others have stated) at least 4 gauge into the box, and a relay capable of supporting 100A+. If you're grounding to chassis, make sure you get a clean mating (sandpaper) at the terminal point, and if you're grounding back to battery via wire, make sure to count that length in your gauge consideration. Your switch box will also need to support 100A input, and technically each switch would need to be individually fused to its limit (say, 40A, probably less).

Keep in mind also, that a 100W LED bar will only draw like 60W (/13.2V = 4.5A). So to some level I have to agree this may be overkill. But then again I have 250A breaker on my audio circuit, so you do you.

 

Although AC and DC are different animals, power distribution can be handled in similar fashion. Agreed that you need to keep in mind the different ratings of different devices in different areas of the distribution. But you still follow the same principals of something like your typical Load Center (Main Breaker and wiring / Sub Breakers and wiring).

 

..I think if your point is he can use smaller wiring out of the distribution box, yes of course I agree.
(I'm a transmission engineer btw, but focused mainly on microelectronics in school, and dabbled in RF so have plenty of experience in all methods of getting current around )

 

Nice to meet you brother. I've been "Playing With Fire" for the past 35 years in the residential/commercial/industrial fields. Currently expanding my knowledge in instrumentation.