I'm installing some LEDs in my RV that I want to operate via dimmer switches, and would like some help validating that I've installed the dimmers switches in the circuits correctly. Please see the following parts list and wiring diagrams for each of the circuits I'm wiring.

There are 2 circuits: one for the front lights, and one for the rear lights. Each circuit is wired with 12/2 AWG wire, and each has 4 LEDs wired in series. The circuits will be controlled via one dimmer switch each.

  • The front circuit has the dimmer switch wired at the terminal end of the wire.
  • The rear circuit has the dimmer switch wired in between LEDs 2 and 3.

Please note the manufacturer's labels on the dimmer switch:

(-) (white) to Earth or Ground

(+) (black) to lamp positive

(+) (red) to power positive

Wiring Diagrams

Front Lights Circuit:

Front lights circuit diagram

Rear Lights Circuit:

Rear lights circuit diagram

Dimmer switch manufacturer recommended wiring diagrams:

Manufacturer recommended wiring diagrams

Parts List:

  • This is confusing, you mention 4 leds in each circuit but show only 2. The dimmer diagram shows them wired in parallel, yet you say you have wired them in series. Please confirm that you have wired them the Dimmer wiring scheme says to. Commented Feb 5 at 11:15
  • @RohitGupta the third image on my post shows the manufacturer's recommended wiring diagrams. The actual circuits I wired are images 1 (i.sstatic.net/f4QzB.png) and 2 (i.sstatic.net/PEerL.png) -- each with 4 LEDs wired in series.
    – mycomyco
    Commented Feb 5 at 17:39

1 Answer 1


The way you have the dimmer wired is incorrect.

The dimmer must be wired after the power supply and before the lights.

The red wire from the power supply is cut and the red from the dimmer is attached to the red wire on the power supply. The black wire on the dimmer is attached to the red wire going to the lights.

The black wire on the power supply is cut and the white wire on the dimmer is added. ( all 3 wires 2 black and 1 white are tied together.)

This will allow the dimmer to dim all the lights. The dimmer location and wiring is the same for both sets of lights.

(forgive my sloppy diagram. It's the best I know how to do)

enter image description here

  • Exactly this. If the input and the output of the dimmer switch are hooked together as in your diagram, it won't do anything. There's no way to put a dimmer at the far end of this circuit unless you add another wire to get a constant power feed to it.
    – KMJ
    Commented Feb 5 at 16:01
  • Got it, thanks for your help!
    – mycomyco
    Commented Feb 5 at 17:38

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.