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How to control 12 volt lighting with two switches?

Dirty Steve

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I want to hook up a switch by the side door and one by the rear door of my trailer to control the 12 lights. I want to be able to turn off and on with either switch. Anyone know how it's done?

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you do not need a 3 way switch for 12v applications. buy a normal switch, and hook them both up just as you would with 1 switch. when you get both +12v wires to the light assembly, tee everything together (12v from switch A, 12v from switch B, and the + lead on your light). if you have multiple bulbs, all the +12v wires need to be daisy chained together.


***NOTE - make sure the switches you use are able to handle the current the light is drawing. the light bulb should give its current rating in A (amps), as well as the switch(s). if you have 10 3amp bulbs, you need to either buy switches rated for 30 or more amps, or you need to use a relay (which is a whole nother wiring explanation)


the cheap $5 switches you find and stores like napa are not rated for much current. a good place to look for switches is an RV dealer. most lighting in campers is all 12v, and they are rated for the current draw of multiple lights (still be sure to check the ratings of each switch to make sure it will work for you)
 
I drew this out and I don't see how the 2 position switch would work.

Say I walk in the front of the trailer and turn on the lights. Then walk out the back door and flip the back switch, the light is going to stay on unless I go back and open the front switch , right?

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I drew this out and I don't see how the 2 position switch would work.

Say I walk in the front of the trailer and turn on the lights. Then walk out the back door and flip the back switch, the light is going to stay on unless I go back and open the front switch , right?

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yes, both switches have to be off in order to get the lights off. i guess i would see no need to have a full blown "3-way switch" setup in a trailer. in your scenario you gave above, you still have to go up front and close the door (unless you can close it from the inside).


if you want an all out 3-way setup, thats over my head. you may be able to use regular 120vac household 3-way switches. (i dont know if an AC switch will work for DC or not due to grounding differences). im pretty good with DC, but AC flies right over my head :face-icon-small-con
 
You can buy RV 12 volt 3 way switches too! It's super easy to wire them (it's just like from the top and bottom of a stairway), you just have to run two wires between the switches so either one works in either position. There is no on/off position on a 3 way switch.

The Google link I posted has pics, video's, website links, etc. It is easy to do.
 
I believe you can ground the light on the 12V system and just switch the power side... unlike an AC system where all legs have to be accounted for.

Use 2 SPDT On-On switches.

Wire the power coming in from the battery source to the center terminal of one switch, run a dual strand wire from switch to switch and connect them to the outer terminals on each switch. The power out to the light comes from the second switch on the center terminal.

When the system is energized, one leg between the switches will be "hot" at all times, the second switch determines whether the light is charged or not. If the second switch is "off", the first switch can be flipped to put electricity down the other "leg" to provide power to the light.

Might be better ways to do it, but that is one way.

http://www.waytekwire.com/item/44127/SWITCH-RECTANGLE-ROCKER-BLACK/
 
A house light switch will work the same on DC as it does on AC. A light switch is just like a toggle switch, open/closed. Doesn't matter if you use the switch to interrupt a power or ground wire.
House switches should be at least 15 amp 250v.
 
There are several ways to hook up three way and four way switches. I drew up the easiest one.

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