gfw

In the wall box where I'm working, there is the hot wire, the load wire (goes to chandelier) and two bare wires that are wired together.

The existing switch ties is grounded to those two bare wires, so I think I'm safe in assuming at least one of those bare wires is truly ground. Is it likely the other is the neutral? Is it normal or common for neutral to be grounded?

Thanks,
Greg

Square Eye

No.
Neutral and ground are NOT the same.
Neutrals should never be connected to a ground wire and ground wires should never be used as neutrals.
So, it's not common. But from what I've seen, anything is possible. That doesn't make it right.
Hopefully you're looking at a switch leg (2 hot wires with a switch between) Maybe the ground wires come from a back to back box?
Need a picture on this one. Are there jacketed Romex wires in the box or are the wires run in conduit? One of the bare wires could be pigtailed from the switch body to the box?

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gfw

I think I understand. There are two complete wires entering the box. Each contains an insulated black, an insulated white and a bare. The two black ones go across the switch, so one is hot from source, the other is hot to load. The two white are wire-nutted together so they are neutral, and the two bare are wire-nutted together with the ground from the switch body, so they are ground. Have I got it?

The reason I'm asking is because I think the dimmer switch I've ordered will require a neutral connection, unlike the switch I'm replacing. I'm replacing the existing dimmer switch because it's incandescent-only, and I just replaced the incandescent chandelier with a 12V halogen one. A lot of the low-voltage compatible dimmers seem to require a neutral connection. Until the new switch gets here, we're using the existing switch all-on or all-off.

kok328

Yes, you understanding is correct and your new dimmer will break the hot and tap the neutral (assuming it needs neutral) & ground.