Can I just cap the extra red wire at the ceiling box and not bother to change the light switch? I know you are supposed to cap the extra wire at the switch but want to know what happens if I don't?

  • 1
    Not much till someone undo the cap and that switch is on. The cap wire will be hot/live whenever that switch for it is on. Should do as much as possible to save a future idiot, they are out there and coming. Look up darwin awards.
    – crip659
    Mar 19 at 21:31
  • @crip659 That's an answer, write it up. Mar 20 at 0:56

1 Answer 1


You could do that and probably nothing will never happen.

The problem is that in the future someone else might remove the wire nut, not realizing that it is still hot/live/has power in it.

There is also the chance that a mouse would eat/chew the insulation of the wire and either cause a short or a fire.

The proper way is to cap both ends and if possible remove the always hot wire from the switch itself, easy if the switch's hot is just pigtailed from the other switch.

You mainly do not want to leave a possible hot wire inside of walls if it is going to be used. It is also nice to leave label/note saying there is a dead unused wire there for future owners.

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