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Law911 03-26-2010 08:46 AM

The Wife said, "The lights are flickering." Dimmer on aluminum wiring
The two wall-mounted lights were indeed flickering in unison. There is a Lutron "Glyder" single-pole dimmer switch (two black wires and green ground) and three cables in one normal size box. One from below, two from above. There was only a single bare aluminum wire entering the box.

None of the dimmer wires pulled free. Two black wires connected by a wire nut, not to the dimmer, were loose. It was not possible to re-cram the wiring back into the same box. The box was replaced with an Old Work Deep. I marked (taped) the wires and replaced them into the new box. In process most marks came off.

The two common black wires were connected. All white wires connected together with a dimmer wire. The remaining black wire to one dimmer wire. The dimmer ground was connected to the single bare wire. But, I extended the two bare aluminum wires to connect with the green from the dimmer. Lights do not work.

Please point to my error. And, any margin of safety that can be gained with aluminum wiring.

Scuba_Dave 03-26-2010 09:27 AM

Is that dimmer rated for use with AL wire ?
How did you extedn the AL wire ? With more alum ?
You can't use copper unless you use the proper AL/CU connectors
What model dimmer ?

Law911 03-26-2010 09:53 AM

The two aluminum grounds were extended with copper pigtails and wire nuts. The 2 grounds entering from above were cut short and twisted together outside of the box. These were the ones pulled into the box and extended with copper pigtails to connect with the dimmer ground and the bare aluminum one.

All aluminum wires were coated with Ox-Gard anti-oxidant compound.

The dimmer, nor the instructions, specify whether or not it is rated for aluminum. It was placed by a previous owner. It is a Lutron Glyder single-pole 600W UL 6B38. The dimmer wires are two black one green and all twisted steel.

The aluminum wiring entering the box seemed brittle -- some wire broke when straightened. I know dimmers get warm. This one seemed more than normal.

Jim Port 03-26-2010 10:45 AM

Most likely the blacks were incoming power, outgoing power and a run to the fixtures. Some combination of these would be connected to the dimmer.

The whites should not be connected to the dimmer.

I seriously doubt that the dimmer is for use with AL wire. Special connectors are also required to be used with AL wiring.

andrew79 03-26-2010 11:19 AM

in most cases an electronic dimmer does need a neutral connected to it. Even old analog style have started to include one. What type of bulb was in the fixture that will tell you the story most likely. you either need an electronic dimmer (which you have) or special bulbs rated for dimming if you've got energy saving flourescents installed. Regular old filament works the best with a dimmer. How dim were the lights? In effect what happens in a 60 cycle system is that the power flows from 120 positive to 120 negative 60 time a second. What a dimmer in essence does is slow that rate down. If you slow it down enough the lights will indeed apear to flicker. Having the light at a low brightness for a long period of time will also cause the dimmer itself to dissipate more heat.
next time your in an office building take a look at the flourescent lights in the ceiling and if you really pay attention you can actually see the flicker from them "turning on and off" 60 times a second.

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