Replacing an old light switch with a new one. Trying to figure out correct wiring

Question

My old light switch did not have the common labeled and just had two brass screw connectors. Coming in the bottom of the box was a black, a white, and ground wire. The ground was connected to another ground and out the top not connected to the switch. The black was to the switch and the white to another white and put the top. Coming off the switch was a red that went out the top. Not sure which to connect to the common connector and which to the other. I also wrapped the ground wire around the ground screw.

Here is how I wired the new switch:

Coming into the bottom of the box was a black, a white, and ground. The ground was wired to another ground coming in from the top of the box, the old switch was not grounded. The white coming in the bottom was connected to another white from the top (I assume straight to the light) the black was looped around one terminal and then connected to a black coming from the top of the box. Then there was a red wire coming from the top of the box on the second terminal on the switch.

This should be a better picture (sorry I’m on my phone and first time posting here). I went and got a single pole switch. Can o wrap the ground wire around the ground screw then up to the ground wire coming in the top?

Answer 1

You have a romex 14-2 coming in the bottom of your box and a 14-3 going out the top. With a plastic box. Single pole switches have no common,connect the black wires together (they are your line side circuit) and around 1 of the single pole screws (doesn't matter which one) connect the red wire to the other screw (this is your switch leg going to your light). the white wires just get connected together, and the ground wires (bare wires) get connected and attached to the ground screw on the single pole switch.

Yes a 3-way switch can be used as a single pole switch, you just have to leave one screw unused.

Answer 2

You are attempting to replace a "normal" switch with a a "3-way" switch, which is why you have a "common" terminal you don't know what to do with.

You also are replacing a switch that depended on the box screws for grounding with a switch that has a ground terminal. You need to maintain the connection to "the ground wire going out the top" and you should also have a "ground screw connected to the box" (unless it' a plastic box - hard to tell from that picture) as well as the "ground screw on the switch" - it is unsafe and improper to connect only to the ground screw on the switch, particularly if (as I read it, which MAY not be what you MEANT) that's at the cost of the ground going out to the fixture. Basically, you need a wire nut for the grounds, and you need "pigtails" (short wires) coming off that to make the connection to the box & switch. "Special for grounding" wirenuts are made that allow one of those pigtails to be from one of the wires going straight through the wirenut - whether you want to bother with buying one for a single switch is up to you, you don't have to use them, a regular wirenut will work.

Edit to add in response to edit of question: Yes, if you have adequate wire to do so, you can just bend the ground wire around to connect to the ground screw on the switch, and keep the wire-nut connection to the top ground wire. The bigger picture does appear to be a plastic box, so you don't have to try to ground that as well.

Best solution would be to get the proper replacement switch. However, you can simply leave one terminal disconnected and use a 3-way as a regular switch:

Can I use a 3-way switch as a single-pole switch?