Installing a dimmer switch

Bobbo wrote:
My sister called me in a panic because she replaced a lightbulb in a ceiling fixture (stick and brick, not RV) with an LED bulb and there was a HORRIBLE sizzling noise, then the light went out. I went over and noted that the light had a dimmer switch and the LED bulb was not dimmable. Replaced the dimmer switch with ON/OFF switch, threw away ruined LED bulb, and all was well.

If a dimmer for an incandescent bulb is used, it will indeed fry the LED. Using an LED dimmer like the OP has purchased will work fine. All 12V LED's are capable of being controlled by that style of dimmer as long as the load is within the dimmers range - 10A in the case of the OP's dimmer.

My sister called me in a panic because she replaced a lightbulb in a ceiling fixture (stick and brick, not RV) with an LED bulb and there was a HORRIBLE sizzling noise, then the light went out. I went over and noted that the light had a dimmer switch and the LED bulb was not dimmable. Replaced the dimmer switch with ON/OFF switch, threw away ruined LED bulb, and all was well.

Unplug the white wire(s) from the existing switch. If the ceiling lights still work but the blue light in the switch does not, that is the ground wire.

If that’s the ground wire, connect it to the black wire on the new switch. After that, determine which of the red wires is 12V by checking with a voltmeter. That wire goes to red on the new switch and the other goes to white. If you don’t have a meter or test light, just hook one red wire to red and the other to white on the new switch. If it doesn’t work, swap them.

be careful with colors. Looks like in your pic the "electrician" just used whatever color wire was close.
Typically RVs use white wire for all ground. So, yours is different already, you cannot go by color, test everything first.
Agree on dimmers not always working with LEDs. Some dimmers make noise when dimmed.
You could always just get a less bright light bulb.... I started to call it a "dimmer bulb" but that would not work here.

Lightning55 wrote:

The problem is that I don't know how to hook it up.

The three wires on the existing switch go to the three wires on the new switch.

ScottG wrote:
That dimmer will work fine for for your 12V LED's. BTDT.

The problem is that I don't know how to hook it up.

That dimmer will work fine for for your 12V LED's. BTDT.

Most 12V dimmers that look like that one are fine for most modern LEDs. I've put a lot of dimmers in my rig!

I agree that it's probably best to disconnect the switch in the panel. I did that because I hated opening the cover just to turn on a light. Remove the switch leads one at a time to see what they do. As I recall, mine are just as you suggest. But testing is smart.

The dimmer needs the neg/ground to properly dim LEDs, where a switch doesn't. If you want to just run the switch lines to the new switch you should be OK.

Hook the wires up as directed by purpose NOT by color. There are several color patterns in use in automotive/RV products, including ones where black and white are reversed! Generally if you get it wrong things just won't work, rather than lighting on fire. Worst case you blow a fuse.

If the lights are LED, you might have to check some more to get a dimmer specific for them?

I don't think any "off the shelf" dimmer is going to work with LED's??

If the lights are your old 1156 bulbs, you can probably get any dimmer for them, but I don't know for sure??

I remember replacing my old 1156 bulbs in my old 2003 Prowler with some LED's and they worked great.. You could still turn on one or two of the bulbs in the fixture from the switch, so that was my 'dimmer'.. :)

I did get some LED specific lights that you could dim with a wireless remote, but they are battery operated and I put them where I needed more light in the corners of my slide out and they work great too.

Good luck! Mitch

The first thing is to make sure teh dimmer and the lamps work together

Second Make sure you have properly identified POWER, GROUND and Load leads on the existing switch

Finally I can not read the labels on the new switch's wires and thus can not advise what wire is which. the image will not open in a new tab (That's a first) so.