A light switch is the simplest of electrical devices. Flip the switch, electricity flows. Flip it again, electricity stops. Lights on, lights off. That’s great for a small room with one entrance.

Q: Tim, I need you to mediate a dispute between my husband and me. We're building a new home, and there are several places where two or more switches can be used to control lights. I like the ...

A conference room has a pair of three-way switches for the overhead lights. One switch is located at the south entrance, and one is located at the north entrance. The south entrance is the one ...