Adding 12VDC circuits

Boat wire

I use the 12v boating convention red/yellow for + - to avoid confusion with black = hot or ground.

Some RV's do run ground wires but the standard for automotive systems (12 volt) is to use the chassis as ground and only run a ground wire as far as the closest chassis attachment point.

NOTE: The reason some RV's do run ground wires all the way back to a ground bus on the fuse block is they are wired by ELECTRICIANS, not Electronic or automotive technicians and as you noted, That is how your "House" wiring is done.

You might also notice the electricans use WHITE as the "Ground" on 12 volt systems (I should add "Often" to that "use") so if adding stuff..> Be sure to use your polarity indicating voltmeter before connecting, You never know how they did it.

IMHO the number one reason for DC problems are bad chassis grounds. Run the negative wire back to the panel.

Believe what you wish ,sir
May God Bless You

"Your house is not DC.
Apples and oranges."

The question was whether in a small RV the chassis is used as the ground in a 12V circuit.

I do not believe you think or intended that to be a constructive answer, and if you did, if telling me what I obviously knew, was intended to be constructive, I am sorry. I apologize to you and am awed by your effort.

AC and DC are apples and oranges as far as wiring is concerned.
If the original post had included the basic info that part of your house WAS DC my attempt to help would have not started with such basic info that AC and DC were different.
Poor comunication and a worse attitude make for hard learning .
I'm not sorry I tried to help but am sorry you didn't appreciate it.
Good Luck, Mike

Hi all. One is reluctant to ask a simple question on these forums because of the temptation it is for some folks to be jerks. For the record, it's not apples and oranges, it's varieties of apples. Also, I'm aware I do not have a metal house, although I can say that on a farm outbuilding I once used a copper water pipe as a return with no problems. And I had a notion that most of my house is not DC, although there are some parts which are.

Thanks to SteveG for the first adequate answer. smkettner is also very helpful and exactly right. It's too late to change brands of box, though I like RoyBs idea of boat wire and will find some at a marine supply. I would rather bring the return back, though will use the chassis if I have to. After all, the box returns wind up back at the chassis.

All of my 12VDC DC Appliance circuits is fed with 2-conductor wiring called boat wire..

Looks like this...


The BLACK wire connects to the 12VDC Power distribution panel fused terminal and the WHITE WIRE is connected to the 12VDC ground bus bar...

This is a typical WFCO schematic showing this


This is another drawing showing the 12VDC fuse circuits using the ground bus bar for all DC circuits.


Roy Ken

You house is not DC.
Apples and oranges.

My oem WFCO center has a negative wire to a ground bus where all the return negatives connect including a connection to the frame. Frame return is just as valid although if unprotected may not be as reliable.