2-wire light switch to 4-wire dimmer switch

[dano50]

The LED reading lights above the bed are too bright for us so I found the dimmer switch on the original equipment manufacturer's web site and ordered two of them. When they arrived I noticed that they have 4 wires instead of two. On the "IN" side there is a red and a black wire and on the "Out" side, a red and a white. The instructions say:
Wiring Instructions:
Step 1: Locate both red wires – these are positive
Step 2: Connect the +IN Red Wire and the black wire to the power source
Step 3: Connect the +OUT Red wire and the white wire to the lights

This may be a dumb question, but here goes: Do they want me to connect the red and black from the "In" side to the existing "Hot" wire and the same thing (three wires together) on the "Out" side? I'm thinking, "Gee, if the 2 wires coming out of the dimmer switch go together, why don't they combine them internally and just have one coming out?"

Anyway, any help would be appreciated.

[96Bounder1st]

At a guess without seeing the actual instructions they expect you to break the power side of the circuit and run it thru the dimmer as it uses a resistor to drop the voltage to the light to dim it.

[dano50]

Originally Posted by 96Bounder1st

At a guess without seeing the actual instructions they expect you to break the power side of the circuit and run it thru the dimmer as it uses a resistor to drop the voltage to the light to dim it.

Sorry, but I'm not sure what you mean as far as which wires should be connected to which.

[96Bounder1st]

You need to connect the positive wire, check with multi meter , as colour codes in RV's are random at best. The positive wire from the battery goes to the red of the in side of new dimmer. The same positive wire you cut or removed from original switch goes to red of the out side of new dimmer. The other wire , assuming there is another , will go in the same fashion to the dimmer. For example, if the other wire is a white, splice the white from the direction of the power source to the black. Then splice the white, again assuming it is a white, to the white of the out of the dimmer.
As far as I know, the only wire that actually is active in the switch is the wire attached to the red of the dimmer.
I wish I could attach a diagram but do not know how.
Terry

[aether_one]

Right now you have 2 wires going to the LED; a positive (+) wire (normally black) and a negative (-) wire (normally white).

When you cut these wires you will have 4 leads; a + and - for the source power, and a + and - for the load LED.

Your IN + (red) goes to the source + wire. The dimmer black wire goes to the - source lead.

Your OUT + (red) goes to the LED + wire and the dimmer white wire goes to the LED - wire.

In no case will 3 wires be connected together.

[96Bounder1st]

Tfryman, perfect description. Thanks a lot clearer than what I posted.
Terry

[dano50]

Originally Posted by tfryman

Right now you have 2 wires going to the LED; a positive (+) wire (normally black) and a negative (-) wire (normally white).

When you cut these wires you will have 4 leads; a + and - for the source power, and a + and - for the load LED.

Your IN + (red) goes to the source + wire. The dimmer black wire goes to the - source lead.

Your OUT + (red) goes to the LED + wire and the dimmer white wire goes to the LED - wire.

In no case will 3 wires be connected together.

Okay, that helps a lot. This means that my dimmer is going to have to be located near the LED and can't replace the original light switch since there is just one wire in and out of the switch but two going to the LED.

Thank you very much.

[96Bounder1st]

Dano59, try connecting the two wires at your switch to the red wires of the dimmer. The wire that comes from the power to the red of the in on the dimmer and the wire that goes to the light to The red of the dimmer switch that is the out.
If possible do not cut ends off just twist and tape for the experiment.
Also not all LED light are dimmable.
Best of luck.
Terry

[aether_one]

Originally Posted by 96Bounder1st

Tfryman, perfect description. Thanks a lot clearer than what I posted.
Terry

Thanks, I was writing it the same time you were writing yours so I didn't see yours until after I posted mine. I thought they said the same thing; at least I understood what you were saying.

[Gary RVRoamer]

Your dimmer is a PWM type and needs to utilize both the hot & ground wires, where as the previous simple switch only had to open/close the hot wire.

It does NOT use a resister, as someone suggested earlier. If it was a resistance type dimmer, it would have only two wires (and it wouldn't work with Leds either). Leds are not dimmed by reducing the voltage - they just blink or go out completely if the voltage gets a little low.

[96Bounder1st]

Thanks Gary, I went and read up on PWM dimmers and have learned something new, again!
This forum is perhaps the best place to learn as there are so many people with such a diverse background. Thanks again Gary.
Terry

[Gary RVRoamer]

Happy to be of assistance!

[nehog]

Just a word to the wise... Do not attempt to connect any of the input wires to the output wires. Many of the PWM LED dimmers common the positive and then modulate the negative side of the circuit. (And as an EE I have no idea why they designed it this way...) Don't consider connecting the two negative terminals to a single ground wire--it won't work.

[dano50]

Thanks for all the input. Regarding the statement that not all LEDs are dimmable, I asked the lighting manufacturer about this before buying the dimmers. They said that theirs were dimmable with their dimmers.

So, I mounted one close to each light following the very clear instructions provided by tfryman (hopefully I am able to attach a photo). They turned out pretty good. It involved taking up the bottom of the storage area directly above the lights so I could get to the wiring.

Thanks again to all of you!