Hurk:
The dimmers you are referring to are probably old resistance units which were introduced in theaters back in the 1920's. These things had the unique capability of dimming D.C. as well as A.C. Loads (since some theater districts in large cities only had D.C. current...more modern day devices can only use A.C.). The common method of installing these guys involved mounting them sideways in a heavy steel frame along the top edge of the actual "switchboard" itself...a large vertical piece of marble, slate, or some other electrically non-conductive surface fitted with dozens of knife switches and fuses. The moveable contact arm on each dimmer (for imposing the required amount of resistance for dimming lights) was connected to a rack and pinion drive handle which was placed within reach of the board operator. Since the dimmers liberated large amounts of heat during operation, this elevated placement got them out of the way where they would not burn someone or start a fire. Since these boards were practically indestructible, it is possible that some may still be in operation, albeit at a tremendous risk of injury or death to anyone using them.

I am very interested in equipment of this type because of it's fascinating historical perspective, and would appreciate seeing any pix you can send along. [Linked Image]

Mike (mamills)