Don't like the adverts?  Click here to remove them

Accessory Activated Bus Bar


New Member
Nov 14, 2022
Country Flag
currently in the process of updating a 2001 90 series land cruiser prado, adding a few small electrical parts, and wondering if it's possible to add an accessory powered bus bar? say run a wire from an accessory fuse to a relay, then from the relay connect to a battery? just with looking at adding a few things, 2 dash cams plus replacing the rear mirror with a digital one since I can't see out the back with the camping set up there, couple gauges, extra usb ports/ cig lighter to the rear seats for charging, you get the idea, lot of wires and multiple fuse splitters which is where my idea came from? On the one hand this sounds like it should work fine, but also I've only tinkered a little with car electrical work so could be missing something?
Yes you could do that and doing it via a relay is the correct way. But I’d recommend using an aux fuse box rather than a busbar so you can easily fuse all your accessories correctly.

I ran the same set up on my FJ, trigger wire from the cabin fuse box to a relay to a common input to a six way fuse box for dashcam, trailer camera etc outputs.

Just be sure not to exceed the total amperage of either the relay (40A usually) or the supply wire and add a fuse to the battery side too for the supply.
I did something similar to power my radios. I fitted a separate battery and small fuse box at the rear, linked to the main battery via a suitably sized cable and a relay with a 10sec delay when the ignition is switched on. You can pay £££ for branded "marine grade" components but there's plenty of decent stuff around at decent prices.