We have an old dimmer switch, single pole, the type with an indicator light internally. It has two black wires, and the green wire is cut off. The plastic box it's connected to has only two wires, one black, one white. They are obviously 120 volts, since the switch has a light in it, and I measured it with a circuit tester. It seems to be described as "electro-mechanical". The part is a Leviton catalog No. 6631, but the instructions I see for these seem to be different than this device, and show the conventional hookup with 2 pairs of wires.

Do I need a special dimmer switch? The one I bought wants two sets of black/white wires, and connects to the black ones, with the white ones shorted.

Or do I need to rewire the whole mess?

Edit I think I might need to rewire if I want anything other than a crappy dimmer; I can't even use a simple switch, because as soon as I turn it on, it might be a short from hot to neutral black to white).

I have no idea how it's connected, actually. Perhaps I'm just being fooled by measuring stray voltage where there is no real current?

I hope there's someone out there who understands electricity enough to explain it.


What you are looking for is a single-pole, 2-wire dimmer. That's a fairly standard item. An indicator light is a little less common, but not impossible to find.

Since you only have 2 conductors in the switch box, your switch is probably wired like this:

enter image description here

  • Thanks, but the directions are exactly like every other dimmer and switch I can find, and will not work. It specifies that the black wire needs to be switched, and the white wire needs to be directly connected. There is no way for me to interrupt the black wire, unless I run one from (presumably) the switch box to the light. I can't even replace it with a normal switch, because it would be a direct short across the hot and neutral when turned on. – Marty Fried Jan 18 '15 at 3:46
  • "direct short across the hot and neutral", where, in the switch box? – longneck Jan 18 '15 at 3:50
  • How do you think the existing dimmer works? – longneck Jan 18 '15 at 3:50
  • I edited my question to add more info. But the short would be at the switch box. There is a hot and a neutral, with 120 volts across it (I checked with a circuit tester, and also, there is a light in the switch). So if I connect these 2 wires to a switch, it can only short the hot and neutral, right? – Marty Fried Jan 18 '15 at 4:18
  • 1
    And before you ask, yes, this does work if the switch has an indicator light in it because in the "off" position, it's not actually off. The switch is actually passing a tiny amount of current through the circuit to power the indicator, but not enough to light up the ceiling light. – longneck Jan 18 '15 at 4:31

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