3 way switch wiring

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Old 06-22-14, 08:54 PM
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Question 3 way switch wiring

My daughter wants me to replace a 3 way switch that controles three outside lights.The wire is 12 gage,the circuit breaker is 20 amps,but the old switch is a 15 amp with one wire for power and three traveler wires.Two wires are conected to the side screws and one wire is inserted in the back of a traveler slot.I do not understand this configeration.Where could the third wire go to,and can you use the side screw and the back space together.Should I use a 20 amp switch for this?
 
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Old 06-22-14, 10:34 PM
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Welcome to the forums.

can you use the side screw and the back space together ?
Can you..... yes. Should you.... no !

You do not have to use a 20A switch on that circuit.

You have four wires on your three way switch. There will be two on the dark colored screw. Remove them from the dark colored screw, connect them together with a short piece of black wire. This new tail will go to the dark terminal and the other two wires will go on the silver traveler screws.


Tech note....
Every three way switch has one dark colored screw and two silver colored ones. Always mark the wire from the dark color screw as it must go back to the same color screw on a new switch.
 
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Old 06-23-14, 05:59 AM
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Where could the third wire go to,and can you use the side screw and the back space together.
Most likely explanation is that power is being fed through this switch box to another device. Follow PJ's suggestion.
 
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Old 06-23-14, 10:32 AM
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can you use the side screw and the back space together ?

Can you..... yes. Should you.... no !
Of course pigtail instead of backstabbing. But technically a switch can be used to feed thru.

So should you? no!

Not because you cant "feed thru" but rather because the OP said this was 12awg being backstabbed.... new devices I don't think are rated for 12 backstabbers only 14.


p.s.- The spec grade switches, with the backwired clamps (not backstabbed) do accommodate 2 wires under one clamp... so technically you could feed thru that way if there was a shortage of wirenuts.

You could even loop a single conductor thru a switch like the old timers used to do... that is also perfectly legal.
 
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