der Mouse <mouse at Rodents.Montreal.QC.CA> said: House 4-way switches DO exist. They have 4 terminals (thus the [USA/NEMA] "4-way" designation). They preform the "normal"/"cris-cross" switching function. A quicky web search <"4-way" switches> got lots of answers, and you can buy these (new, sorry not 10 year old) devices. The first return from a yahoo search has a nifty animation on how this all works. The technology has been in use for quite some time (the house I grew up in used a 4-way switch in the 50's). The problem is that not many places stock the things (I looked on Home Depot's site to no avail). Basically the switch train is a bunch of exclusive-or's so that any switch can make the "sum" 1 (on), or 0 (off). I had to get a computer reference in there somewhere! If you do decide to do some wiring, be careful. There are lots of references on the web on the "how-to" aspects. Ob antique stuff: Yes, the house also (the part built in 1946) had knob & tube wiring. The other part (built in 1952) where the 4-way switch was had something resembling romex. -- Tom Watson tsw at johana.com ____________________________________________________________________________________ Want to start your own business? Learn how on Yahoo! Small Business. http://smallbusiness.yahoo.com/r-index