I have two doors and I put the magnetic switches in line. So if either door is open the light will come on. It's also tied to my sump, so if any of the three doors open the light comes on. It saves me one spot on the Apex.I've got 4 doors. but as long as one activates. The tape lights are nice too. Trying to make sure the heating elements were under water was a tight area to see in a small dark box.