I've wired almost all the light switches in the house with Lutron switches. So I have a lot of experience with installing them. For some reason this one is giving my problems. This switch controls a light that is plugged into a switched outlet.

It looks like the romex to the switched outlet is 14/3 since I see a red wire. I shouldn't need the red wire though, correct? The old toggle light switch had a pigtail from the line wire to the switch and the red wire was connected to the switch as well with no ground connection.

I've attached an image of how I have it wired. Do I have the switch wired incorrectly? I don't even see the faint green light on the dimmer switch when the breaker is turned back on.

enter image description here

  • 2
    Is the switched outlet fully(both) switch or only half switch? Does switch only control top or bottom of the outlet? It is possible that 14/3 was used just because it was handy, but usually is used because the red is needed.
    – crip659
    May 31, 2023 at 19:05
  • Newer code requires there be a neutral wire to all switch boxes, if needed or not, dumb switches do not use neutral. Neutral must be white, but white can be used for power(marked with black). 14/3(or 12/3) is now used for switch loops where black and red are hot and switch hot. So red is probably important.
    – crip659
    May 31, 2023 at 19:27
  • Why is one Lutron black going to power (left = 'to another room' but 2 wires so presumably one power in, one power on to another room) and one going to another light switch? May 31, 2023 at 19:28

2 Answers 2


Stop. You can't install a dimmer on a receptacle.

Unless you use really special "lamp-only" receptacles made for that purpose.

You're welcome to change that to some sort of non-dimming smart switch, but a dimmer is Right Out unless you ante up for the custom receptacle and plug for the lamp.

Why the red wire, though

There is generally a receptacle every 12 feet along a wall. People often find it inconvenient for the entire receptacle to be switched, and why does a light need 2 sockets? So typically, the receptacle is split, with one socket always-on like normal, and the other socket switched. That would be consistent with the /3 cable.

One hot wire (typically black) is used to carry always-hot, and the other hot wire (typically red) is used to carry switched-hot. Neutral is shared. The receptacle's "hot" (brass) side has its tab broken off, and black and red each get a screw.


The old toggle light switch had a pigtail from the line wire to the switch and the red wire was connected to the switch as well with no ground connection.

The red wire is the one that needs to be switched, then, and the black wire should be connected directly (unswitched) to line.

The 14/3 cable contains a red wire for switch-controlled power to something (the switched outlets); it contains a black wire for always-on power to other things (possibly the other half of the switched outlets, or maybe just feeding power to other non-switched things further along in the circuit); it contains a white wire providing a shared neutral for the switched and the unswitched loads.

  • Using red for switched hot is a good bet and convention - it's not, however, a rule or code. But conventions are useful, just not utterly dependable.
    – Ecnerwal
    May 31, 2023 at 19:36
  • 1
    I understand a switched outlet is ok, but I thought a dimmer controlling an outlet was a no-no...not so?
    – RMDman
    May 31, 2023 at 19:40
  • @RMDman Ah! You're right. I overlooked the fact that the control is a dimmer. :-(
    – Greg Hill
    May 31, 2023 at 21:02

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