Accessory Relay

Hello All,

I bought an accessory fuse block mount, and a two bus fuse block. I’m going to get a 100A circuit breaker. I want one bus to be always on, and one to have a relay controlled by the ignition, so I can choose which accessories can be on regardless of whether the ignition is on (light bar, USB power in cab) or only when ignition is on(dash cam, ham radio). I’m thinking of using a single relay to power the 2nd bus. Will this work? Suggestions on what relay to buy? Do I need two circuit breakers? Thanks!

 

An appropriate sized relay to handle the fuse block. Typically people wire their accessories to individual relays instead of a single relay to a fuseblock.

 

I’ve seen that people say to use a separate relay for each accessory, I’m just not sure why?

 

I would do something like coming in through the 100 amp main. Break that up e.g. one to several, 20-30 amp fuses. Put a relay rated at 20-30 amps after one of the 20-30 amp fuses. The relay should be rated for the fuse ahead of it. After that I would put fuses rated for the individual devices e.g., a 5 amp fuse on the USB power etc.

 

TE Connectivity V23232-A0001-X003 Power Relay, Parallel and Series Diodes, SPST, 12V, 75A

 

That’s perfect, thank you!

 

That’s more amps than my house had when I first bought it!