Wiring a ceiling light fixture and light switch

Old 07-28-03, 01:49 PM
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Wiring a ceiling light fixture and light switch

In a bedroom in my house, I decided to replace a ceiling fan with a halogen ceiling light fixture. The junction box has three old non-metallic 2-wire cables coming into it. One line is from the power source, via another few junctions between the circuit box and the junction box. The second line runs from the junction box and terminates at the on/off switch, which controlled the fan. The power source does not come through this switch to the light, but from the box to the switch. The third line runs from the junction box to yet another box, continuing the circuit.

The light fixture I am trying to install is a simple piece, with one black, one white, and one ground wire. I have tried every conceivable wiring combination, but cannot get the switch to turn on the light.

Two goals define what I am trying to accomplish. First, the on/off switch must turn on the light. I am using a single-pole dimmer switch. Second, the power source must provide electricity to the other boxes, switches, and outlets further down the circuit.

Here is what I think is supposed to work.
1. I tie the white wires from lines 1, 2, and the light fixture together.
2. I tie the black wires from line 1 and line 3 and the white wire of line 2, and mark this white wire as “hot” with a piece of electrical tape.
3. I tie the black wire from line 2 together with the black wire from the light fixture.
4. I ground the light fixture to the junction box.
5. I connect the brand new on/off dimmer switch to the wires in the switch box as follows. I connect the white “hot” wire to the one black wire on the dimmer switch, according to the instructions that came with the dimmer switch. I connect the black “neutral” wire to the other black wire on the back of the dimmer switch. I connect the ground from the dimmer switch to the light switch box.

With this configuration, I achieve the second goal of having power in the boxes, switches, and outlets further on in the circuit. However, the dimmer switch does not turn the light on and off.

Any suggestions on how to overcome this problem?

Old 07-28-03, 02:11 PM
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Because of heat concerns, installing a halogen light on older wiring is a questionable choice. Didn't the fixture come with a warning about installing it on pre-1985 wiring?

Here's what you should do (line 1 is power, line 2 is to the switch, line 3 continues the circuit):[list=1][*]line 1 white to line 3 white to the light fixture white.[*]line 1 black to line 3 black to line 2 white.[*]line 2 black to the light black.[/list=1]Note that this almost, but doesn't quite, match what you said you did. Actually, what you said didn't quite make sense since you used the white wire from line 2 twice and didn't use the white wire from line 3 at all.

Just a point of terminology, but there is no "neutral" wire at the switch. Both the black and white wires are hot.

If you have it wired as I said and it still doesn't work, then you probably fried your dimmer switch with some earlier experiment that tripped the breaker than you were too embarassed to mention.

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