In Reply to: double switch circuit design posted by vincent on 02/17/01 at 7:42 AM:
When you have two separate light switches, one at each end of a hallway or a staircase for example, either of which can turn a light on or off regardless of the position of the other, you have what are called "three-way" switches which are sold at most any hardware store. Each switch is of SPDT configuration.
The wiring is very simple, but an installation of the switches and wiring should only be done according to code and only by a licensed electrician.
John Dunn - President