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.