dimmer switch caused problems

Old 01-23-03, 07:25 AM
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dimmer switch caused problems

After I installed a dimmer switch in the bedroom a light switch in the adjoining room no longer works. Where I installed the dimmer switch there are 3 sets of black and white wires. The 3 white wires are capped and 2 black wires are connected to the dimmer switch. I'm guessing the 3rd black wire needs to be connected somehow to allow the light switch in the other room to work. How do I connect that 3rd black wire? Do I connect it to one of the other black wires? Thanks in advance!!!
Old 01-23-03, 07:35 AM
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Did you connect the dimmer switch the same way, to the same wires as the previous light switch?

Does the other light work at all? Dimmer switch full bright, full dim, and off?

Is the bulb in the other room still good?
Old 01-23-03, 07:41 AM
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This is a very common mistake.

Two of the black wires need to be connected to one dimmer wire, and the third black wire to the other dimmer wire. This is the way it was before with the old switch, but perhaps you didn't look closely enough before you disconnected it. In standard switches, it is common to use the screw and adjacent backstab hole to use the switch to electrically connect the two wires. This technique is usually not available for dimmers.

So which two of the black wires go together? You can figure it out with a lot of testing, but trial and error works okay. There are only three possible combinations. So try one of them first.

Pick any two of the black wires at random and connect them to either one of the dimmer wires. Connect the third black wire to the other dimmer wire. Turn the breaker back on and test. You will have one of three situations.

(1) The lights in the room with the dimmer are always on and cannot be turned off with the dimmmer.

(2) The lights in the room correctly work with the dimmer, but the lights in the next room are also dimmed by this dimmer.

(3) All works well.

If you have situation (1) or (2), turn the breaker back off and try again by pairing a different two black wires. As I said, there are only three possibilities and one is bound to produce result (3).

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