All you need is a screw terminal for wire painted the same color as your switch plate. Loop it over the switch, secure it with the screw above, and no more accidental flipping.

While most older houses were wired with 14-gauge knob-and-tube, for the switch loop use 12-gauge NM (nonmetallic sheathed cable), commonly known as Romex™. The cable contains a black wire, a ...