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I have an old light switch that I want to upgrade. The old switch does not have a ground screw (see second image) so the bare copper ground wire is just tied to the metal box with a screw (see "B" in the first image).

My new switch comes with a ground screw and a ground wire pre-attached.

Also, there does not appear to be a neutral wire here (correct me if I'm wrong) so I made sure to just pick a new switch that does not require neutral.

I just want to make sure, when I install the new switch what is the best way to go about it:

  • Remove the existing copper wire from the box screw and attach it to the light switch's ground wire?
  • Leave the existing copper where it is (B) and attach the new switch's ground wire to the box at A?
  • Or pigtail the existing copper to the new switch and then put it all back at B?

I know there are other similar questions answered on the site, but I wanted to provide pics of my exact setup to make sure. Thanks.

(also, whatever the solution is here, would it also apply to something like smart relays?)

Front of box

Back of switch

orr
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2 Answers2

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There are a lot of problems there.

The left of the three cables has two unterminated wires in the box. What’s with that? At LEAST they should be capped off, but what are they, and why is their ground wire in use (but incorrectly)?

The left switch is grounded by a wire from that left cable. The box is grounded by a wire from the right cable. I can’t see where the ground wire goes from the middle cable. But none of these are connected together as they should be.

I'd like to suggest that whoever did this has so little understanding of electrical wiring that it should be inspected and rewired by a professional electrician.. If the same person did other wiring in this house you NEED to have it looked at by a professional.

At least in this box, all the ground wires need to be connected to each other and to all the switches and to the box. It’s not critically important HOW you do that. Ideally, the wire that is closest to the actual source of ground should be longer, should be connected to the box screw first, and then wire nutted to all the rest, and the switches should all be pigtailed to that. Usually in an existing box you can't be picky ... you use the available wire to connect everything together as best you can without breaking them, as long as they ARE ACTUALLY connected by proper nuts or devices.

jay613
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Leave the ground at B as it is, connect the ground of the new switch to A.

With metal boxes there is less need to connect a ground wire from a switch to the box, since the metal screw mounts of the switch act as a ground path.

White wire is usually used as neutral in circuits, but in your case the cable is being used as a switch loop. One wire is always hot/live(should be the white and is nice to put black tape on it) and the other wire is called switch hot, becomes hot when switch is on.

Newer smart switches do usually require a separate neutral and new code requires three wire plus ground cables for them(black, red, and white for neutral).

crip659
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