The "COMMON" wire color? Replacing an old dimmer switch.

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Old 06-09-15, 04:10 PM
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The "COMMON" wire color? Replacing an old dimmer switch.

Hey guys,

I am installing a new dimmer switch. I removed the old switch from the wall box and found 3 wires: Black, Red, and Green.

Now the new dimmer switch has me confused:

There is a screw for Ground (obviously the Green wire);
but then screws to attach "Single Pole" and another for "COMMON" (the "COMMON" screw is black).

Is "COMMON" my 'hot' Black wire? ...or the red?

Thanks! I'm in Massachusetts, USA.
 
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Old 06-09-15, 04:39 PM
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The common only matters in a three way switch.
 
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Old 06-09-15, 05:16 PM
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Actually, I should have been more specific: the instructions have 2 options.

For 'single pole' it instructs to attach 3 wires - 1 labeled "single pole" (Wire to Light), 1 labeled "COMMON" (Wire to Source), and Ground.

For '3-way- it instructs to attach 4 wires - 1 labeled "single pole" (traveler to 3way), 1 labeled "COMMON" (wire to source), 1 labeled "3-way" (traveler to 3way), and Ground.

I have 3 wires coming out of my wall only, Black, Red and Green so I assumed the "single-pole" option... but I just don't know which wires are which.

Thanks again.
 
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Old 06-09-15, 08:07 PM
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If there is only one switch to operate the fixture you need the single pole wiring.
 
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Old 06-09-15, 08:10 PM
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Single pole to red. Common to Black.
 
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Old 06-09-15, 08:17 PM
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Thanks! ...I tried it, it worked and nothing blew up.
 
 

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