I've pulled out the single pole switch and there are three black wires, two of which are connected to the same screw and one connected to the screw on the opposite side of the switch. Both screws appear to be brass and there is nothing connected to the odd colored screw on the switch. When I put in the new dimmer switch, do the three black wires get connected in the same way on the dimmer switch leaving the odd colored screw empty?

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    Can you send a pic? May be the green ground screw, or a neutral. Guessing green ground. – user101687 Jun 12 at 13:16
  • I can't send pic at this time – Lisa Jun 12 at 13:26
  • Can you get us a pic at some point then? It's really hard to judge what's going on from your description alone.... – ThreePhaseEel Jun 12 at 22:26
  • One more tell if it's a 3-way switch you are replacing.... does the handle have an On/Off label molded in? Because 3ways are dependent on the other switch state, they will be bare. – DaveM Jul 13 at 2:03

Yes your wires get connected the same way (but not 2 wires under 1 screw, unless it is a clamp designed for 2). If you are connecting the 2 wires and they are wrapped around the screw only 1 wire can be bone that way so a pig tail is needed a short pice of the same gauge wire wire nutted with the 2 wires then to a screw terminal, or better yet if the new switch has leads just tie the lead to the 2 with a wire nut and you are good to go.

  • My ground wire is separate and was grounded correctly the three black wires just stumped me I'm used to seeing a white one or a red one. And I didn't mean to imply that both black wires were under the same screw on the side that had two wires. One was under the screw and one was inserted in the hole in the back of the screw. My concern is that there wasn't any wires leading to the odd colored screw. – Lisa Jun 12 at 13:26
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    They are using a 3 way switch as a normal on off switch, not a problem, I have done this on occasions where I was a switch short, 3 ways cost more but not as much as a run to the parts house or big box store. I would pigtail the new switch, I don’t like back stabs they have been the cause of a huge majority of wiring failures I have been called to repair. – Ed Beal Jun 12 at 16:37

Two separate wires should never be attached to the same screw. Are you sure they are two separate wires and not a single wire with the insulation stripped off in the middle?

If it is two separate wires, a short black pigtail wire should be used. One end of the pigtail attaches to the screw on the switch and the other end is joined to the two black wires in the box using a wire nut or other suitable connecting device.

Is the "odd colored" screw green? This is the ground connection. Inside your junction box, there should be two or more bare copper wires joined together. Since it sounds like you old switch wasn't grounded, you will need to create another pigtail (using bare copper wire) and join it to the other bare copper wires in the box and the other end connects to the ground screw on your new switch.

A picture showing what is in the box would be very helpful to make sure everything I said above is accurate. A lot depends on where in the world you are located and the age of the wiring.

  • Believe it or not this is a brand new house. The switch being removed has two brass colored screws and one silver colored screw and one green screw. The green screw is grounded correctly with the ground wire. The silver screw is empty. The brass colored screws are at the top of the switch on either side. There is a single black wire going to the brass screw on the left hand side and the other two black wires are leading to the brass screw on the right hand side inserted like I said. – Lisa Jun 12 at 13:30
  • It sounds like this is a three way switch. But they way you've described the connections doesn't make sense. There should be something connected to the silver screw and either of the brass screws, not both brass screws. – Jim S. Jun 12 at 13:50

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