How to tell black wire from black wire?

andee_gwMay 27, 2010

I'm replacing a light switch in the bathroom. The existing switch has two black wires and I don't know which should go to the red wire and which to the black wire of the new dimmer switch.

The existing switch has one black wire that comes from the wall (along with a white wire for the receptacle) and is screwed at the top of the switch. The second black wire attached to the bottom is also attached to the bottom of the adjacent fan switch. The fan switch top black wire disappears behind the receptacle.

Can anyone help sort this out for me? Thanks!

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Doesn't really matter, but connect the black from the dimmer to the black that goes to each switch, and the red from the dimmer to the single black.

    Bookmark   May 27, 2010 at 10:01AM
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Hey Normel, it worked! And the house didn't blow up and I quit sweating. Thanks so much -- I'll do another one.

    Bookmark   May 27, 2010 at 10:22AM
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Ron Natalie

If the house blows up, just swap the wires :-)

    Bookmark   May 27, 2010 at 11:05AM
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lol... or what's left of them.

    Bookmark   May 31, 2010 at 12:38AM
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