I just recently installed a light switch. It's not a dimmer switch, so there's just an off and on. Now, the lights are constantly on! When I turn the light switch off, they dim slightly, and when I turn the light switch on, they brighten slightly. How might I have messed up installing the light switch that this happens? Could it be the switches fault?

Process I used to install light switch:

  1. Remove old light switch. Wires going into old light switch are: bare copper wire attached to green lead, 2 black wires going into copper leads red wire going into black lead.
  2. Connect new light switch. New setup is: bare copper wire attached to green wire labeled "ground" on switch, 1 black wire attached to black wire labeled "in" on switch, 1 black wire attached to red wire labeled "out" on switch, 1 red wire attached to white wire labeled "neutral" on switch.
  • 6
    So you wired it differently, and now it doesn't work. Surprise!! But more worrying, you have probably now compromised the electrical safety of ALL your house lights, until you sort this out. Since you don't say what country you are in, we can only guess what the correct way to wire this would be.
    – alephzero
    Commented Aug 20, 2019 at 10:36

2 Answers 2



You have messed things up. Sorry to be blunt. But electricity is dangerous, so this is really a big deal.

Safety First

Turn off the breaker for this circuit. NOW! What you have described might be fairly benign, but you might have caused some parts of your electrical system to be "hot" that should not be.

Assuming you are in the US (if you are not, please say where you are as different countries have different color codes):

  • Neutral is white or gray and only needed on a switch if it has "smarts" of some sort (timer, dimmer, WiFi controls, etc.)
  • All other colors (except green/bare == ground, which you have handled correctly) are HOT or SWITCHED HOT.

Your new switch has a neutral connection? That implies it is something more than "just a switch". Not a dimmer (since you said so), but is it a "smart switch"? A timer? Something else special? In any case, the red wire is not neutral and should not be connected to neutral on the switch. If you actually need neutral then you need to find neutral - typically a bundle of white wires stuffed in the back of the box, but sometimes not in the switch box at all because old construction did not require neutral in the box.

Old switch: "2 black wires going into copper leads" - what does that mean? Was it two black wires connected together onto one wire or screw? If so, they likely need to be connected together to the "in" connection on the new switch. If they were two separate connections on the old switch then this is impossible to guess, but a 3 way switch is a possibility.


A picture is worth a thousand words. Please upload pictures of the old switch (preferably showing model # if you can), the new switch (again showing model # if you can), and the switch box showing all wires as clearly as you can.


It's really time to leave mains electrical to the professionals - or at least a competent handyman with some years under his belt.

The first problem is that you say this is an ordinary switch. It's not. Ordinary switches do not have built-in pigtails, and they especially don't have neutral wires. They don't use current themselves, so they don't need to return current to source.

The second is that neutral is involved. Neutral is a curent return, and while there aren't many meaningful color codes in US wiring, neutral is always white or gray. Attaching a wire labeled neutral to a wire that isn't white or gray is instantly wrong.

These are "electric 101“ concepts that you shouldn't be struggling with. Being unable to identify the type of switch you're installing is particularly disconcerting. Lack of knowledge is curable, of course; however you do have to actually do that.

To your credit, you connected the wires thoughtfully, once, and got help; rather than play "wire roulette" as we see many people do.

Also, you identified the importance of the screw colors, which give it all away.

This switch will not work here. The old switch was a 3-way, because there is a second point of control for this light. I also suspect you are in the conduit wiring system given the wire colors I see in use.

As you have surely gathered, it is not simple at all.

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