From another place:
>My house was built in the late 50's with everything electric made by GE.
It had a GE heat pump, an electrostatic air cleaner that looked like it was from a nuke plant, even GE wire nuts! It still has the 24volt latching rel ay system for the lighting. There are 18 circuits for the output, directly from the relay to the lights / outlets. All over the place I have 3 wire lo w voltage runs to rocker switches that control the relays. While this may s eem a nightmare, the whole thing works very well. The relays are still used in big commercial buildings , still available, and everything is pretty ro bust. Because the control can be easily ganged I have the ability to turn o n the upstairs hall light from within each bedroom and downstairs so it is the equivalent of a 7 way switch. From the master bedroom there is a rotary selector and rocker to control every circuit on the system.