Bus Bar For Accessories

I posted this in the Lighting Forum but figured I'd post this here since there’s probably more traffic.

Currently, I have two light bars and will be installing some reverse pods and possibly under the hood lighting. Looking to clean up the wiring in the engine bay. I have the negative bus bar sorted but looking for guidance on the positive bus bar.

Do I simply run a wire from the positive battery terminal and connect it to the positive bus bar then add all the positives from the accessories?

What gauge wire from the battery to the bus bar?

Where would be a good place for the positive bus bar? On top of fuse box? other?

 

Yes, run a larger wire from the battery to any terminal on the bus bar, same as your ground. Just make sure you have a fuse and relay in-between your bus bar and accessory. It would also be smart to put a circuit breaker or fuse rated for the sum of your accessories in between the battery and the bus bar just incase something shorts the bus bar or your main power wire.

The gauge depends entirely on wire length and expected amperage draw. Just follow a table like this:

 

All lights have an inline fuse and relay.

So gauge appropriate wire from neg terminal to neg bus bar. Gauge appropriate wire from positive terminal to positive bus bar with a fuse or circuit breaker in between.

This type of fuse?

$22 Blue Sea Systems 5191 Fuse Block Terminal 30-300 AMP

Blue Sea Systems 5191 Fuse Block Terminal 30-300 AMP: Battery Terminal Fuse: Amazon.com: Industrial & Scientific

If I go with a circuit breaker, am I on the right track (still need to figure out the total amperage)?

$26 RED WOLF BS6100 100A Amp Circuit Breaker W/Manual Reset Switch DC 12-48V for Car Audio RV Marine Boat Truck Trolling Motors Stereo Audio Electronic Battery Solar System

RED WOLF BS6100 100A Amp Circuit Breaker W/Manual Reset Switch DC 12-48V for Car Audio RV Marine Boat Truck Trolling Motors Stereo Audio Electronic Battery Solar System Waterproof : Amazon.ca: Automotive

 

The way those charts work is by determining percent voltage loss, like 1, 3, or maybe 5% depending where you find it. So if you break up your entire cable run and size each segment using the chart, you'll end up losing more than the specified percent. That's why it says total run. I have a calculator I made for sizing wire without the guesswork, but you should just oversize the leads going from your battery terminals to the bus bars, then use use the chart as intended for your accessory runs. If you know your amperage loads and wire lengths I could tell you exactly what I'd use.

Either of those styles would work, but I recommend using a circuit breaker just so you don't have to carry extra fuses around.

 

Yes, I understood the chart (thank you for that). I just needed to figure out the total amps of the lights which is 21.17.

Thank you for recommending the circuit breaker over the fuse. I was leaning that way after some thought today.

I appreciate the help.

 

I like using the circuit breakers over a fuse, definitely get good quality breakers, these are made in USA and available at Digikey
https://www.digikey.com/en/products/detail/mechanical-products/175-S0-040-2R/12698414

 

The sum of the accessories is 22 amps. Should I be putting a 25 amp or 30 amp circuit breaker? Larger? If I add more accessories in the future, I would just buy a new circuit breaker accordingly?

 

So long as each accessory has its own individual fuse off your bus bar, the breaker or fuse for your bus bar power lead can be sized appropriately to whatever cable you run from the battery to the bus bar.