I opened up a box with two switches to witness this:

enter image description here

The hot (which is white, I've confirmed) is looped around the far light switch, then pushed into the connector in the back of the near light switch. Each of the red and black wires (neutrals I think) then complete the circuit, so I guess it works.

Is this an undesirable configuration? I'm trying to replace them with simple dimmer switches, and what I would like to do is pigtail the single hot with the hots of each dimmer switch. Each switch would still have it own neutral. Is this a better way to go than the current setup?

  • 1
    No the red and black are not neutrals, they are switched hots going back to the lights/outlets those switches control.
    – brhans
    Commented Aug 8, 2020 at 3:44

1 Answer 1


This is called a switch leg the white should be taped black or another hot conductor color. Your red and black are the switched hots going to the lights.

You don’t have a neutral in your case so your dimmer can not require a neutral it is possible a dimmer that requires a ground will work if the ground is connected at the other end and back at the panel but most LED’s won’t work with an old school dimmer because they draw a little current through the light this causes LED’s to glow or flash but will be fine with incandescent lamps on a dimmer. That’s why I mentioned the possibility of a dimmer that uses the ground may be an option for LED’s.

  • Are you sure the red and black must be hot? I don't detect any current running through them when the switches are off. Commented Aug 8, 2020 at 1:25
  • 3
    @dfitzgerald -- they're the switched-hots, so of course they won't show up as live when the switch is off Commented Aug 8, 2020 at 1:38
  • 2
    To clarify, I hope, or muddy - Hot is hot from the power source. Switched Hot is from a switch (connected to hot) to a Load, and Neutral is from the other side of the load back to the power source (panel.) The current flows through hot, and switched hot, and the load, and neutral - but the "transition from hot to neutral" takes place at the load, NOT at a switch.
    – Ecnerwal
    Commented Aug 8, 2020 at 1:49
  • 1
    If they are simple dimmers that do not need neutral, you're set. You do not have Neutral at this box, at all - which is perfectly normal for older wiring with a switch loop. Eventually there was a code change that put an end to switch loops in new (code compliant) installs. You do still need to re-mark that white wire with a "hot color" (black red orange yellow blue purple or brown) - not gray or green.
    – Ecnerwal
    Commented Aug 8, 2020 at 2:41
  • 1
    I find it amazing that all the comments repeat the answer with multiple votes on the comment but not the answer.
    – Ed Beal
    Commented Aug 8, 2020 at 17:03

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