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We have an old dimmer switch in a two-switch box (next to a regular light bulb) (in California). The old dimmer switch's button no longer works right, so we wanted to replace it with a new one. We got a Lutron switch to replace it, and I looked over the instructions, but when I saw the wiring of the old switch it made me hesitate. The main thing I'm concerned about is the ground wire.

From the old dimmer switch, there is a capped off (unused) black wire and it has a red wire and a black wire connected to white wires in the box. This is a little different from the new dimmer switch which just has two black wires (besides the ground wire), but as far as I know I would connect the two black wires to those two white wires. Feel free to comment if that is right or wrong.

But for the ground wire, what I expected was that the box would have a green or copper wire coming out of the box with the old dimmer switch's ground wire connected to it. Rather, the old dimmer switch's green ground wire looks to be almost grabbed onto by a group of wires like fingers.

So what should I do? Is this normal wiring? Is it safe? Should I mimic it with the new switch? Should I leave it to an electrician? Are there particular instructions that I should follow, or would I need any special tools to open/close the fingers around the ground wire if I were to do the same thing for the new dimmer switch?

As it is, I pushed everything back in the box and screwed it back in (I hadn't disconnected any of the wires). Thank you.

wiring of dimmer switch image of ground wiring connection

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    Note that those aren't really white wires, they're painted wires, big difference :)
    – ThreePhaseEel
    Nov 10 '20 at 1:35
  • @ThreePhaseEel Is there anything I should know about that? Do I connect the two black wires from the dimmer switch to the two painted white wires? Is there anything that being painted white would indicate compared to how I see other instructions that have red and black wires in the box?
    – A L
    Nov 10 '20 at 3:10
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    When you see paint slopped all over the wires in a box like that, it has no significance other than "a sloppy painter or drywaller was here". I'd carefully scrape the paint off the wires you want to hook up to the switch so that you can verify their wire colors
    – ThreePhaseEel
    Nov 10 '20 at 4:07
  • Black or colored paint is allowed re-mark a white wire for use as a hot. That is the only re-marking allowed. Nothing can be re-marked to be neutral.
    – Harper - Reinstate Monica
    Nov 10 '20 at 18:02
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The old dimmer is not properly connected to ground (an attempt was made, but it's not good workmanship...)

The grounding wires are crimped (which seems to be a popular method at some places and times for grounding wires, I assume because someone felt it saved 3 seconds per box or something) but the old dimmer grounding wire is not in the crimp, it's just jammed between the crimped wires.

If one or more of the grounding wires that are in the crimp stick out far enough on the other side of it you can use a wire-nut to properly connect your new dimmer's grounding wire. Can't see if that's the case since they appear to be behind the other switch in your pictures.

If not, you can cut off the crimp and use a wire nut to connect all the grounding wires and your new dimmer grounding wire.

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  • Thanks. When you say if it sticks out far enough on the other side, wouldn’t they all just connect to something in the box without any accessible end in that direction? Maybe one of the wires that is “grabbing” onto the old switch’s grounding wire could be connected via a wire nut? Or if I were to connect them all to the new ground wire with a wire nut, wouldn’t I need a much bigger wire nut? (Why is there more than one wire in that group anyway?)
    – A L
    Nov 10 '20 at 1:44
  • Also, to clarify, is that group of wires the correct grounding wire to use? Since it looks strange and this is new territory for me, I want to be able to know that I would be doing it right and not anything unsafe.
    – A L
    Nov 10 '20 at 1:50
  • I can't tell from your picture which way they actually run - I'm assuming the bit where the old dimmer ground is stuffed in is about where there's a bend towards the back of the box. If it's the free end instead, then it looks like you don't have room for a nut there. That group has all the grounding wires from all the cables connected to this box, which is how grounding happens for everything connected to those cables. A wire nut will have to be an appropriate size for the number and size of wires.
    – Ecnerwal
    Nov 10 '20 at 1:52
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    @AL I'd just make sure you have some good sized wire-nuts (or 8 or 12 port push-in connectors for that matter) on hand before you start, you really aren't going "off book" at all, more cleaning up the "off book" thing the last bloke did and making it actually yanno, meet Code
    – ThreePhaseEel
    Nov 12 '20 at 2:51
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    @AL -- pick up a book on basic house wiring from your local library I reckon
    – ThreePhaseEel
    Nov 19 '20 at 12:45

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