Needing a ground for Dimmer Switch

[Trapshooter]

I tried a few different searches but didn't find any postings that solved my dilemma.

I am wanting to change out the OEM light switch and install a dimmer switch to tone down the lights over the dining table and lounge chairs in our slide. They are way to bright.

The issue I have is the OEM switch is in series with the light circuit. The new dimmer switch I have needs a ground circuit to operate.

I tested the new dimmer switch in the circuit and using a jumper to the ground from an AC outlet that is close to the on/off switch. The dimmer worked great with the existing lights.

I tried fishing around in the small hole where the wires come out of the wall to the switch but couldn't find any other wiring. Since the lights are mounted in the slide there is no access via the top.

Since my camper is still new and under warranty I really do not want to start tearing into things.

Here are some photos of what I have:
Photo #1 - OEM Switch
Photo#2 - Back of OEM Switch - Green/White Power In. White to Light Fixture
Photo#3 - New Dimmer Switch
Photo#4 - Back of New Dimmer Switch

Any thoughts or ideas are greatly appreciated!

[Wingerdinger]

You are going to have to find the negative wire coming back from the lights, it's not necessarily ground, it is the return wire from the lights.
On my camper, many (all?) of the 12 volt negative wires are white, and they are often tied together. Maybe find a junction of white wires, meter to confirm that they have no voltage, and try it?
The dimmer diagram assumes you have the negative grounded, that is not always the case, and rare on a modern camper.

[Trapshooter]

Originally Posted by Wingerdinger

You are going to have to find the negative wire coming back from the lights, it's not necessarily ground, it is the return wire from the lights.
On my camper, many (all?) of the 12 volt negative wires are white, and they are often tied together. Maybe find a junction of white wires, meter to confirm that they have no voltage, and try it?
The dimmer diagram assumes you have the negative grounded, that is not always the case, and rare on a modern camper.

Thanks Wingerdinger, I figured that would be the case. I pulled one of the lights down out of the ceiling. There is a white wire coming in and a black come out. I didn't check for voltage at the time but will. I would bet the black is the ground. I need to fish around some more and see if I can get something to tie the new switch into.

[Wingerdinger]

Originally Posted by Trapshooter

Thanks Wingerdinger, I figured that would be the case. I pulled one of the lights down out of the ceiling. There is a white wire coming in and a black come out. I didn't check for voltage at the time but will. I would bet the black is the ground. I need to fish around some more and see if I can get something to tie the new switch into.

On a typical RV, wire color is different from the rest of the world. Go Figure.
Real commonly, black is POSITIVE and white is negative.
On your picture of the fixture, You will notice a '+' symbol next to the black wire, and a '-' symbol next to the white wire.
A lot of people connect their battery backwards and blow fuses because of this.
In the same panel as the light switches, you will probably find groups of white wires; all the negatives tied together.. test one of those for no voltage.

[Trapshooter]

Originally Posted by Wingerdinger

On a typical RV, wire color is different from the rest of the world. Go Figure.
Real commonly, black is POSITIVE and white is negative.
On your picture of the fixture, You will notice a '+' symbol next to the black wire, and a '-' symbol next to the white wire.
A lot of people connect their battery backwards and blow fuses because of this.
In the same panel as the light switches, you will probably find groups of white wires; all the negatives tied together.. test one of those for no voltage.

WOW, thanks for pointing that out! I totally missed that. This so goes against everything I learned in automotive and aviation maintenance. Rest assured I will not be wiring any circuits until I confirm were the power is coming from.
Thanks.............

[TerryH]

YES, Grab a ground at the fixture itself; *** but **Warning** DIMMER MAY/ MAY NOT WORK SATISFACTORY. With 120vac LED Lights at home that are NOT marked "Dimmable" I have found (some) SOMETIMES irratically turn into STROBES after 5-minutes or 5-30-minutes, and same STROBE can happen if Non-dimmables connected to DAY/ NIGHT or MOTION sensors. Sometimes, would be NICE to feel we (really) understood what we "thought we knew"? ** Do quality work/ connection, and you will have no warranty issues.

[Wingerdinger]

Originally Posted by TerryH

YES, Grab a ground at the fixture itself; *** but **Warning** DIMMER MAY/ MAY NOT WORK SATISFACTORY. With 120vac LED Lights at home that are NOT marked "Dimmable" I have found (some) SOMETIMES irratically turn into STROBES after 5-minutes or 5-30-minutes, and same STROBE can happen if Non-dimmables connected to DAY/ NIGHT or MOTION sensors. Sometimes, would be NICE to feel we (really) understood what we "thought we knew"? ** Do quality work/ connection, and you will have no warranty issues.

The negative (not ground) at the fixture would mean running wire all the way to the switch, that's just not practical. The fixture is 12 volt. I use a dimmer in mine, it depends on the dimmer, it must be for 12 volt LED.

[Ckenmore]

Did you ever find a work around for this? I ran into the exact same issue trying to replace the OEM switch with a dimmer for the LEDs in my slide out. Id rather NOT try to run a new wire from the fixture (-) all the way to the dimmer on the wall..

[Wingerdinger]

As we mentioned, all the negative wires are tied together, there should be mo need to go back to the fixture. Find and confirm zero voltage on a (usually white) wire near the switch. I successfully installed a remote controllerd dimmer at the switch that controls all six of my main overhead LED fixtures.

[Ckenmore]

thanks for the reply. i fished all over in and near the switch on the wall and there is no gang of white wires I even used an endoscope and nadda. If its hiding...its hiding good. I just have the 2 wires that go to the OEM switch and thats it. Dimmer is the exact same as above in the OP and the OEM switch is the exact same as well. The slide looks to be the same as well. I have a 2022 299QB. The dimmer has a Red (12v), Black (Ground) and White (Load/Light). The wiring in the wall of the slide has a Green (12v) and a White (Load/Light). If I attach the Black Ground and the White (load/Light)) from the dimmer into the White (Load/Light) of the wiring in the wall.....and attach the Red (12v) from the dimmer into the Green (12V) wiring in the wall, the lights will work and dim beautifully.....but......the dimmer starts to heat up a little. Obviously, thats NOT the way to do it...unless you want a really big expensive camp fire. But other than trying to run a wire from the (-) in the light fixture to the switch on the wall of the slide....I just dont see a path forward

[Rrizz]

Have you tried hooking up the switch without using the black ground?
Red to Green/white, White to white?
Obviously the OEM switch is a simple line break, with no ground there. This would mean the light itself is grounded.
My next question would be is the switch backlit? if so, that may be the reason for the ground wire.
Thats the only reason there would be a ground on a 12 volt switch, as far as I know.

[Rrizz]

RV Dimmer Wiring Options. It appears the ground is for the dimmers electronics.
Heres a good informative page on RV dimmers...