Switch makers have built all kinds of cool features into modern “smart switches.” You can buy switches with occupancy sensors, timers and programmable dimmers. But the catch is that, unlike an ordinary switch, some of these new switches require a neutral to operate correctly. This is a problem if your old switch is wired as a “switch loop,” such that only a hot and a switched hot are available in the box. Before you shop for a new switch, remove your old one from the box—after making sure the...
