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Once again I am going through a room and replacing the switches, and once again I am stumped on how to proceed.

We have a switch in the laundry room which controls a light in the garage. I assumed it was 3 way because there is another light in the garage which controls the same light. So I bought a switch with a pilot light and prepared to go to work.

However, the switch seems to (like many of the others in our house) follow some weird wiring pattern. Here's a picture of the back of the switch:

Back of old switch

And here is the new switch I'm trying to install:

Front of new switch

https://imgur.com/a/Gr9NH

Could someone walk me through how to wire this up? Thanks in advance!

EDIT: Added more pictures.

Side of old switch

Other side of old switch

  • I need to see the sides (screws/terminals) of the old switch – Ben Welborn Aug 20 '16 at 20:46
  • @BenWelborn - added! – Brynn Flynn Aug 20 '16 at 20:55
  • Does the little red (pilot) light always stay on or does it only come on when you turn off (or on) the light? – Ben Welborn Aug 20 '16 at 21:05
  • @BenWelborn - in the old configuration, the red light behaved as expected in a 3-way configuration. If the garage light was on, it was on. If a switch (either the one I'm replacing or the one in the garage) was flipped while the light was on, both the light and the garage light would go off. So it seemed like a standard 3-way. – Brynn Flynn Aug 20 '16 at 21:09
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    @BenWelborn So it only came on when the light was on. – Brynn Flynn Aug 20 '16 at 21:13
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The wire painted red is called the common wire (it's connected to the actual light). The two blue wires are the travellers. The pink wire is not necessary. Use a wire nut to cap it off.

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To maintain the 3 way function of the two switches, just make sure the red wire is identified when you take out the old switch. Be sure to put that common-wire on the black screw of the new switch. The traveller wires go on the brass terminals. You can reverse them or not.

Tip- if the new switch is such that it is down while the other one is up when the light is off, you can either reverse the traveller wires or spin/flip the switch upside-down (there really isn't an up or down on a 3-way switch), so that both switches are pointed down to turn the light off.


If you want to eliminate one of the switches (suppose you just want one switch in the garage- not the laundry room), then, in the laundry room, just connect the common (red) wire to one of the travellers with a wire nut. Use another wire nut to cap off the extra traveller and use a pice of tape to mark it "J-Biden".

Now you should go to the other switch (in the garage) and take the unnecessary traveler wire off the switch. You have a 50/50 chance of removing the correct wire, so just take one off, and try it. If the switch doesn't work, then the traveller wire you took off is the one you need... put it back on the switch and take off the other traveller. Put a wire nut over the unused traveller and use a piece of tape to mark it "B. Obama".

Don't forget to turn off the breaker before you touch it.

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