Skip to main content ↑ ↓
Topic: DC 12V (-) & AC 120V (Ground) connect on to same base plate? (Read 1327 times) previous topic - next topic

DC 12V (-) & AC 120V (Ground) connect on to same base plate?

Those who know a bit more than I do about AC and DC electrical systems, please help me get a clarification:
Motorhome is not grounded like a house, a house electrical breaker box is grounded with a coper rod in to earth.
Now when I am talking about 120V AC, I am not talking about Neutral (White) but the Green/Ground wire.
<I am never talking about the hot (+) side of the wiring>
So everything in our coaches must be grounded to chassis, 120V AC (green wire) & 12V DC (green or sometime black).
Therefore anywhere inside our coaches a 120V AC ground/green and 12V DC (-) ground/green wire can be terminated on to a same plate/bolt/metal plate without any issues correct?
Thank you,
Al
Former 2003 GV U295 (6230) (2015 - 2025)
Former 94 GV U225 (2013-2016)

Re: DC 12V (-) & AC 120V (Ground) connect on to same base plate?

Reply #1 –

Yes
No~Shock~Zone RV Electrical Safety: Sokol, J Michael: 9780990527916:...
Foretravel does some weird spliced in wires in the headlight. Colors are weird and confusing. No shock is a good read for everyone
Scott

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: DC 12V (-) & AC 120V (Ground) connect on to same base plate?

Reply #2 –
Al,
You are correct that white is the normal color for the neutral conductor on a 120v AC system, it is also the normal color for the "ground" in a 12v DC system. Black is normally the "hot" in  120v AC if using just the 3 normal colors in romex black, white  & green.
But the black wire is also the "hot" or "positive" in our 12v DC coach wiring. So it is normal to see the "white" 12v DC wires connected to the same point as the "green" 120v grounds, all should be bonded to the chassis frame.
hope this is as clear as mud............................
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: DC 12V (-) & AC 120V (Ground) connect on to same base plate?

Reply #3 –
The wires are coded and it's easy to match them up when you look at the schematic. For the wires exposed to the elements, the codes may not be readable so you have to find out what there are for and label them. Our isolator had been changed and all batteries wired together. Took a little figuring out.

Take a photo before you pull wires off anything so you get it back together correctly.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: DC 12V (-) & AC 120V (Ground) connect on to same base plate?

Reply #4 –
Quote from: propman –
So everything in our coaches must be grounded to chassis, 120V AC (green wire) & 12V DC (green or sometime black).
Therefore anywhere inside our coaches a 120V AC ground/green and 12V DC (-) ground/green wire can be terminated on to a same plate/bolt/metal plate without any issues correct?


I'll throw in "possibly" as an answer.

Ground is not to be viewed as a giant reservoir/hole where all electricity goes when it's done doing its thing.  You see, the current flows in a loop - from source through item you're powering and then back to source.  That's why when you're missing a ground connection in DC, things don't work.

Good wiring/design makes the return path as short and direct (and low impedence) as possible.  That's because stray return currents can cause unintended behavior/electrical noise if they find flowing through other devices "easier" than the desired path. 

Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320
 

Re: DC 12V (-) & AC 120V (Ground) connect on to same base plate?

Reply #5 –
And if you are welding on your coach and don't want to disconnect your ECU, power, etc., connect the ground cable on the welder as close as possible to where you are going to strike an arc.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)