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12V Camper Branch Circuits – Parts & Components

12V Camper Branch Circuits – Parts & Components

This list will show you some of the more common parts and pieces necessary to wire all of the 12V branch circuits in your camper.


Thursday 23rd of September 2021


Do you have any recommended / affiliate links for the following? I feel like you must, but I just can't find them!

-USB Outlets (C and standard) -Combo 12v USB Outlets -Light Switch and Dimmer (Does the dimmer and switch need to be separate units as indicated in your 12v wiring diagram?)

Lastly, I am following your 2000w Inverter Charger Budget Friendly Wiring Diagram, which shows a single red wire going from the shunt to the busbar. I presume this is so the battery indicator can function. I purchased this one:

Anyways, it's the only wire in the diagram that you do not have a sizing for, why is that? Do you have a recommendation based on the info I have provided?

If it helps, I am currently running 320W of Solar and have 1 100amp Lithium battery and will add a second if needed.

Thanks again, Keaton

David R

Tuesday 30th of March 2021

Hi Nate,

First of, thanks for the great site. I purchased your 12v wiring diagrams and had a question on the 12v powered from a single location with the 4 Common Circuit ST Blade Compact fuse block [#4045] (Page 6/9). I am running 4 similar LED circuits with the PCA Electronics compact dimmer switches (

Question: My intent was to have a master switch between my panel and and the 4045 SD blade so I can simply make sure all the lights are off if I leave the van.

1. Do you recommend a switch for this location and should I use a different SD Blade fuse block that what you have listed on your site. 2. Can I consolidate the negative to the lever nut shown and then to the negative on the new switch and then to the panel? 3. Based on the above, should I be using a different dimmer.

Thanks, David

Steven Wolfe

Wednesday 17th of March 2021

Hi Nate, I saw your video on building a custom buss bar a few weeks ago and have gathered all of the components to proceed. I saw your recent posting on that video warning that you no longer recommend using this plan. I have a Renogy 12v 3000watt inverter/charger and 3, 12v 120 ah Lifepo4 batteries that I want to install in my RV with 30a service. I was all geared up and have begun to build this. You've stated that there was a problem with inferior fuse holders. Do you have any other possible suggestions for me to improve this design? Going with the Victon Versa (or whaterver it was, am on my phone and forgot the exact recommendation) is not really feasable for my budget. Can you offer me any other options? I do plan to operate my upgraded equipment conservatively. Thanks, Steve Wolfe

john k

Wednesday 10th of March 2021

hi nate-

although it took me a couple days of thought, the solution was very simple- i had the polarity of the switches reversed. well, DUH! two of my five lights are now working and i guess i have to troubleshoot the other three. this weekend's mini-project!

until next time...


john k

Monday 8th of March 2021

hi nate

have a question about switches

i purchased all the stuff for wiring my van through your list, carefully did the wiring. it was a tense and exciting moment when i installed the battery and turned on the power. No smoke! eureka!

i installed 5 12v plugs through the distribution box, tested them all, they all worked. installed two reading lights through the distribution box, tested them, they worked. bought a 5M light strip, cut it into five pieces, tested them all on a separate battery. they all worked. installed them with the SPST switches on your page. tried to test them. every one of them blew a fuse

WTF? any suggestions as to what i do next?

all the best

john kumiski

Nate Yarbrough

Saturday 13th of March 2021

I saw through a later reply of yours that you were able to troubleshoot and figure it out. Nice work!