I've got a Jayco Eagle HT 30.5MBOK 5th wheel that has about 7-8 ceiling lights. They are way too bright so I want to install a dimmer switch. The new dimmer switch looks very similar except it has a slide dimmer next to the ON-Off rocker switch. When I pulled out the original switch I determined that the red wire with white stripe is hot. It is looped with a connector that is spliced into the wire that plugs into the back of the switch (see pics). It's 12v hot all the time. The black wire goes to the lights and is powered when the rocker switch is turned on. The new switch has 3 wires and the instructions to hook this up is not at all what they describe the wiring in the instructions that came with the new switch. I'm stumped....It seems that the light circuit is powered up and the rocker switch completes and interrupts the circuit but the dimmer is set up for a different wiring system. Any 12V gurus out there that can give me some help?

I'm assuming your light's are LED's. Some led lights are not dim-able.

Hi,Another question: The dimmer you purchased, is it for 120V lighting circuits or 12V lighting circuits? Can you post the make and model number of the dimmer switch?~Rick

Your pics are not showing. That will probably simplify your question if you can get them to post. As stated above confirm it is a low voltage switch.It sounds like it can be set up as a three way switch.

It may not be as simple as which wire goes where.My dimmer replacement called for a PWM (Pulse Wave Modulated) dimmer, not a simple 12v resistance type.ExampleGoogle "12v modulated dimmer switch" for multiple sources.

Need help with dimmer switch | Good Sam Community

dieseltruckdriv
Explorer II
Sep 06, 2019
philh wrote:
Awesome you found a solution

In a different forum a couple of people had good luck with this item
Link to Amazon dimmer

Just for reference if anyone is curious, I have three of these in my 5er and LOVE them.
1492
Moderator
Sep 05, 2019
Moved from Technology Corner
RickLight
Explorer III
Sep 04, 2019
Thanks for letting us know!
Lightning55
Explorer
Sep 04, 2019
OK, job done, dimmer switch installed and works perfectly. I found a white wire in the wall where the switch mounts and it tested as a ground wire. All I did was tie into it and the system works as designed. No fishing wires down the wall. No flickering lights when dimmed. DW is very happy. Two of these lights are in the hallway and I wish they were on a separate switch...but that's a project for another day. Thanks for the help.
philh
Explorer II
Sep 04, 2019
Awesome you found a solution

In a different forum a couple of people had good luck with this item
Link to Amazon dimmer
RickLight
Explorer III
Sep 03, 2019
No, not all whites are ground. In fact 12VDC systems don't have a separate ground like household 120VAC systems. Negative is usually the chassis that works sorta like a ground. If you have a return from the lighting then you don't need a new wire.

Color codes also vary widely. You'll find products from outside the USA often have black and white reversed from our normal black=negative. Sometimes you'll see red instead of white, or yellow, or, or, or they're just all the same color!!

This guy does a great overview of dimmers for RVs.
https://youtu.be/wv7h8jDPZ8g
Lightning55
Explorer
Sep 03, 2019
Thanks for the input. I found that the white wire from the new switch has to be grounded. I ran a jumper from the ground lug in the electrical panel to the white wire and it works perfectly. Now I have to fish a wire down the wall to the panel box to hook up to ground.
Question: I see a lot of white wires in the wall near my light switch. Are white wires always grounds? If so, couldn't I just tie into one of these rather than fish a new wire down the wall to the electrical panel?
Dick_B
Explorer
Sep 02, 2019
The previous poster's dimmer is also shown in Camping World (white option) as a dimmer especially made for low voltage. $45!
Dimming LED's are more complicated than the old incandescent bulbs because of the internal circuitry in each LED that is not always compatible with store-bought dimmers.
RickLight
Explorer III
Sep 02, 2019
Is the dimmer like this?
https://www.amazon.com/dp/B07D2CPJ3S

If that's at all right you should be in good shape.

Do you have 4 wires? 2 from the source, 2 from the light.

Does your dimmer have 3 wires or 4. If 4 then it's just a matter of sorting line and load, positive and negative. If you have 3 wires then one will go to both negatives and all join together. The others to positive and load.

If you only have 2 wires then you may need a different dimmer.
Corkey05
Explorer
Sep 02, 2019
It may not be as simple as which wire goes where.

My dimmer replacement called for a PWM (Pulse Wave Modulated) dimmer, not a simple 12v resistance type.

Example

Google "12v modulated dimmer switch" for multiple sources.