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atouchet 04-10-2009 05:20 PM

3-Way Switch
I have one outside backyard light that can be turned off/on from a switch in the garage or from one in the house. I'm trying to add additional backyard light to work off this three way circuit but I can't run the new wire to the existing light base without busting bricks and/or removing hardy-plank; the garage is detached (the existing light is by the backdoor). Can I add the new light and have it work by both switches if I can only get to the wiring at the garage switch? I tried taking the new light wire and connecting it to the neutral white wire to the existing white wires and connecting the black hot wire to 1st the bottom pole of the switch and then to the top pole of the switch; the new light stayed on constantly and would not turn off.

Any help is greatly appreciated.


SD515 04-10-2009 05:52 PM

What color and how many wires are in the switch box in the garage? What are they hooked to? If it's a proper 3-way setup, in order for your idea to work, the garage switch box would have to have the neutral in it (and wouldn't be attached to the switch at all) and the common terminal of the 3 way switch would have to be connected to the black wire of the load, not the black of the source (feed) power.

dSilanskas 04-10-2009 06:41 PM

If you can get to the switch that has the leg from the light going to it you can come off of that switch.

220/221 04-10-2009 08:01 PM

Existing light is on the house and you want to add one on the garage?

I'm gonna say no. Not using existing wires.

If you are lucky, the circuit is installed in conduit. You need another wire in the mix.

There is probably some crazy hillbilly way of doing this but I don't think it's a good idea :jester:

PaliBob 04-10-2009 08:21 PM

1 Attachment(s)
Allen, Here is a typical 3-Way ckt

What you need to know is where is Switch #1
Is it in the house or in the Garage?

If it is in the house then you can tap off the common of the Garage switch.

Or just tap off the existing backyard light

atouchet 04-11-2009 12:05 PM

1 Attachment(s)
Palibob---I cannot get to the existing backyard light; the garage is detached from the house and the wires run through the breeze-way connecting the house and garage. Therefore, to get to the existing light, I would have to rip hardy-plank and bust brick...too expensive. How do I know which switch is #1?

SD515---the wires that are coming into the garage light switch box are red, black and white. All the white wires are twisted and capped together. The red wire from the 14/3 wire coming in is hooked to the bottom of the switch and all black wires are twisted and capped together except for the Black wire from the 14/3 line; it's connected to the top of the switch. The other black wire connected to the bottom of the switch is black jumper and tied with the other black wires that are twisted and capped; the main source wire from the panel is included in this bunch. see attachment.

PaliBob 04-11-2009 01:23 PM


Originally Posted by atouchet (Post 258330)
How do I know which switch is #1?

Allen, From my diagram in Post #5 the common terminal of switch #1 will always be Hot regardless of the position of either 3-Way switch. Check the diagram.

The common terminal on a 3-Way has the odd colored screw. Look at the color of the three screws. Two will be the same and the third screw will be a different color. This is the common terminal.

* Set either 3-Way switch to where the backyard light is OFF
Check the voltage on the common of one of the two switches:
* If there is Voltage........That is Switch #1
* If there is No Voltage....That is Switch #2

Some Cheapo Testers:
Neon Screwdriver
Cheapo DMM
Voltage Sniffer

joed 04-11-2009 05:50 PM

How many cables inthat box? I know we have at least two since you have two black wires.
If you only have two cables, is the black from the two wire cable hot if if it is disconnected from the switch?

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