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Full disclosure: I know very little about electrical work and was hoping for an easy fix.

I have been getting a buzzing from my dimmer every time the dim feature is used, and I read that a low quality dimmer can cause this. I read that this one is good, so I purchased it as a replacement: https://www.amazon.com/gp/product/B000BOA23U

I flipped the breaker and then tested the light switch to make sure the light wouldn't turn off. I removed the old dimmer, which had two black wires and a green wire.

Both black wires were connected to their own black wires in the wall (seen below coming toward the camera), but the green wire was not connected to anything at all. I'm really not sure what to do as I suspect that not having a ground on a dimmer could be causing the buzzing and could be unsafe. Here's what it looks like in the wall:

Wires in the wall

So...what should I do to make this safe?

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  • I agree with most of @harper answer below but thought I should ask what kind of lamp or lamps are you driving with the dimmer?
    – Ed Beal
    Jan 6, 2017 at 20:07
  • 4 recessed lights that are using 60W incandescents and another light fixture with 2 25W incandescents.
    – Nathan
    Jan 9, 2017 at 14:17

1 Answer 1

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A dimmer that buzzes is using an obsolete way to dim. It's also buzzing all your surge suppressors and the AM radio for half the neighborhood.

Grounds are not used in any way whatsoever as part of the functioning circuit. Electrons should never move on a ground path. So the dimmer shouldn't need it to function, but a newer, better dimmer might need a neutral wire. Make sure you are considering future LEDs when picking a dimmer. The better LEDs (GE, Cree) are really quite good now, and it's time to say goodbye to incandescents.

I do see a ground wire back in there. It also looks like a steel junction box. It is likely the ground wire is either strapped to the box (typically with a #10-32 screw) or is otherwise attachable with a wire nut, possibly already attached to other wires.

You also see the metal yoke on the switch. That is meant to be ground. You see where the yoke is resting on plaster, not the steel box itself, so the ground path there is weak - depending on the metal screw. Because of that, I'd use a wired connection of bare (or bareD) wire to go from an attachment point to the ground screw on the switch.

By the way, that little paper square on the bottom of the box, is designed to go on the screws on the switch yoke. You slide or screw it onto the screw, and now it will stay captive and not fall out. Sometimes they get unscrewed by accident as you're removing the switch.

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  • I think this answered most of my questions. Thanks!
    – Nathan
    Jan 9, 2017 at 14:18

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