I replaced a light switch installed at the bottom of the basement steps with one that has a dimmer. When I opened the junction box i saw there are two Romex wires coming in. One is connected to the switch at the top of the stairs which makes sense as this is a three way switch. I don’t know what the other one is connected to. The copper is connected to the ground, but the black and white wires are exposed and not connected to anything. Is this some kind of standard practice I’m not aware of or should I disconnect the ground and cap off the wire? I’m assuming the mystery wire is not live. I’m picking up a voltage meter tomorrow to confirm. Even if it’s not live, I feel uneasy having exposed random wires in the box. Any advice or input would be greatly appreciated.
Best Answer
It's not unusual to see an unused wires folded up in a box with the ground connected and the other conductors capped. Unfortunately it's very rare to see anything marked or labelled to help the next guy figure out what's what.
This one's a little different in that it's clipped short on purpose - someone wanted to discourage trying to use the wire - and the wires are not capped.
I'd cap the wires and leave it alone. Turn off the breaker for the light circuit, test to see if the short wire is live, and if so find and turn off that breaker. I'd peel back the jacket 1/2", carefully strip 1/4" or so off the black and white, and twist on a small wire nut.
Tracing the wire to figure out where it goes and the rest of the story could be a bit of a project, and there's nothing to indicate any hazard, so I would not bother.