Ok- so I hope I explain well- I will also attach photo. Dimmer switch and switch to fan located in same box. When we removed the plate, the cords came out of there locations before we could see what was attached to what. We have: 2 white wires that had a yellow nut connecting them; then we have a red wire, 2 black wires and a green grounding wire. The new dimmer also included a yellow "jumper" wire. We are wanting to replace the current dimmer switch and also the switch next to it that controls the fan. The old setup has wires coming out of the switches attaching to the wires in the wall with yellow electrical nuts. The new switches don't have any wires at all (other than the green grounding wire)- just the screw or wire-in-the-hole hookups. We are having a hard time figuring out the connection map. We can't tell which one is the common or "hot" wire. We don't have any electrical tools to tell us either. The new dimmer switch has a blue screw, a gold screw, and a black screw. The new regular switch has a black screw, a gold screw and a green screw. Can someone PLEASE help by telling us what to hook which wires to on both the new dimmer and the new switch? Even without knowing which is the "hot" wire, is there a couple of different configurations that could help us figure that out? Thank you so much!!![image of wires in wall]1

  • Hello, and welcome to Stack Exchange. Another picture, especially of what's below the current picture, might help. If you can't post a second picture, post the URL, and someone will be along to edit it into your post. Mar 20, 2016 at 2:29

1 Answer 1


I'd be surprised if the wires coming in from the bottom of the box (the 14/2 NM) weren't the supply (hot). It's fairly common to use a 14/3 for the run between the switches and the light\fan. In that you only have 2 cables coming into the box and you're working with single-pole switches, the easiest way to verify is to use the regular switch to test for the hot.

I'd connect one of the non-green terminals to the red wire coming in from the top and one of the non-green terminals to the black wire coming in from the bottom. Switch it on, and turn the breaker back on. My guess is that either the fan (most likely) or light will come on.

You can then confirm this by turning the breaker back off, removing the red wire from the switch, and replace it with the black wire coming in from the top of the box. Turn everything back on, and the other device should be on now.

After you've confirmed that the bottom black wire is the hot, follow the installation instructions on the new switch and dimmer. You'll need to connect both of line terminals on the switches to the hot. You can either jumper them (tacky) or wire-nut two pigtails onto the hot and connect one to each switch.

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