Adding a 12 volt power point

The previous owner of my RV added several 12v power plugs by tapping into the light housings before the switch. Both ground and hot are there because the lights are mounted on wood cabinets. He used a Molex plug which is much smaller than the standard cig lighter type.
We find it very handy for charging devices, portable fans, lights etc.

Norm

budwich wrote:

TomG2 wrote:
Some of these answers remind me of the old "knob and tube" house wiring where single lines were interconnected all over the place to save a little copper wiring.

Reminds how those houses are still "in use" today.

Now you know where the original phrase, "Hot wire" came from. It's a wonder there were not more house fires as modern appliances were added to the string.

To the OP: I tied into an unused converter fuse and ground connection to run the two wires to a nearby 12 volt outlet. (#10 twisted wire and 20 amp fuse.)

TomG2 wrote:
Some of these answers remind me of the old "knob and tube" house wiring where single lines were interconnected all over the place to save a little copper wiring.

Reminds how those houses are still "in use" today.

I would have thought 120VAC would use an earth ground from the shore cable. Never saw how it was wired before.

Some of these answers remind me of the old "knob and tube" house wiring where single lines were interconnected all over the place to save a little copper wiring.

I think you need to ensure that the circuit (AC) in question is not going back to a GFI which you will be tripping if you "mix" the "groundings".

Thanks for all the replies,
What I am finding is that because the 120 volt AC common and ground are not connected in a RV the ground is connected to the chassis as is the ground for the 12 volt DC.
It should work fine. "A ground is a ground" The only problem is when I forget why I did it next week.
The reason for the power point is to get power near the bed for my cpap machine. The machine pulls 2 amps without the humidifier and 5 amps with the humidifier. I will try not to use the humidifier.

Reminds me of a story,
One of our firefighters said that she would get shocked when she got into the engine at the station. None of the other firefighters complained about it. I went to the station and got into the engine and nothing. Asked for her to come out and show me. She walks out in her stocking feet. So the diagnostician that I am I took one boot off and grabbed the handle. Yes she she was not lying. We found an open ground at the shore line connector.

Ed

A ground is a ground, however the 12 V supply typically has much higher currents so the wire size might not be appropriate. But the best reason to not do this is that it contravenes code. If there is ever a fire, even if you are sure it has nothing to do with wiring, your insurance may not cover you. For a couple bucks worth of wire and drilling 1 hole, why risk it? Also do yourself a favor and run the 12V return to either the ground window or the actual battery, not the frame or you'll be messing with it a couple times per season for as long as you own the camper.

?

120v shorts to the same ground whether its at the box or back at the terminal strip, if you look at the posted diagram.... a ground is a ground.

Connecting a 12V (-) phase wire to a 120 V AC receptacle ground opens the possibility of a 120 V device shorting to ground and putting 120 V AC on the (-) phase of the 12 v circuit. That is not a good thing.

Any connection to frame or the battery negative, either directly or through the (-) phase wiring in the 12V distribution panel is what you need.

An alternative is to connect to (-) at another 12 V device but since you may be using this power port with devices that draw significant current, you would have to make sure the originally wired 12 V device has sufficient wire size for both that device and the device powered by the new power port. In most cases, that will not be true. Better to wire directly to frame or battery negative.