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12V Camper Branch Circuit Guidebook

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12V Camper Branch Circuit Guidebook



This is a 7-page guidebook for installing 12V accessories that will show you common ways to wire the 12V accessories around your camper like lights, fans, USB outlets, and such.  This guidebook includes the wiring examples as well as recommended wire and fuse size recommendations that are specific to the items being powered.  The following circuits are shown: 

  • 12V Lights – Switched with functional LED switch indicator
  • 12V Lights – Switched with led switch indicator disabled
  • Alternate wiring for 12V lights
  • 12V Lights – Switch w/ dimmer
  • 12V lights – 3 way switch (Switches in 2 separate locations)
  • 12V lights – 3 way switch with dimmer (Switches in 2 locations, dimmable from 1 location)
  • 12V lights – powered from a switch panel
  • Single Maxxair Fan
  • Dual Maxxair Fans
  • 12V Outlets
  • Combo 12V USB Outlet / 12V Outlet
  • USB Outlets
  • Water Pump
  • 12V Refrigerator

You can learn more about and source all of the little bits and pieces found in the guidebook here:

Note: This is a high-resolution PDF eBook.  Although it is indeed able to be printed, some of the smallest details on the page may be too small to see when printed (like the ‘spade connector’ label on the spade connectors), but are completely visible when viewed digitally.

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Tuesday 6th of April 2021

Do you have a diagram for a 4-way switch (controllable from 3 locations)?


Tuesday 30th of March 2021

Hey Nate,

Huge fan of all the things you create for us DIYers! It's incredibly helpful. We're hoping to find a dimmer switch more like what we have in our apartment. I was looking on Amazon and found this:

Would this work in the same way as the SPDT switches you show in your diagram? We have 2 zones of lights in our van we want to control and be able to dim separately.

Thanks a ton!



Monday 22nd of March 2021

Awesome guide!

Have a follow up question the diagram there are times where you have multiple wires (12v single panel diagram has 5 negative in) of the same charge going into an orange block. Can you tell me what this is supposed to represent and then maybe provide a link to a product you would use? Thanks!

Also, anything on using 3-way switches with a single panel switch as well for the second light switch location?


Wednesday 24th of February 2021

Hi Nate, I've purchased a few of your diagrams/guides and they have been super helpful! Quick question - I notice in some of the 12v lighting diagrams the dimmer is wired separately from the on/off switch. Do you recommend DIY'ers install a separate dimmer and on/off switch, or is the diagram this way for ease of reference? Any thoughts on the 2-in-1 switch with dimmer? That would seem more convenient but I'm not sure if there is a material differnece. Anything else I should be looking out for in selecting the switches for my build?


Thursday 14th of January 2021


Nate Yarbrough

Friday 15th of January 2021

Thanks! Glad it helped!