Is there a maximum number of switches that can be used to turn on a light. I work for a high end residential design firm and it is typical for us to provide light switches at every possible door/opening into a room to turn on the light. Besides being unbelievably stupid, is there a code or hazard to having too many switches connected to a light? It would be nice to have a good reason to tell my boss the next time he makes me draw 5 switches to a single light.

Nope. No limit at all.
Sorry.

There is no code limiting the amount of switches for anything.

Of course there is a limit to distances, assuming hardwired system, since each switch needs at least one three wire cable, most with two, voltage drop can be an issue with large buildings, esp if the load is large. If there is only a few lamps or low wattage, probably not notice this.

There are so many ways to have multiple control points, without using long runs of 3 wire copper cable.

Low voltage wiring, not used too often now, was the rage in the late fifties. Now there is wireless, and X-10, that I know of.

Wireless is radio frequency, and X-10 switches connect to 120 volt power and transmits a addressable signal to receivers at the desired loads and operate switching relays. That's enough to get you going.

There are many others here that may know more details about these systems.

I have used X-10 devices several times. I would have a master control board anywhere in the mansion, usually with only my new load as a start to the system. The owner could control their tennis court lighting,and path lighting, as you needed a mansion for these courts. Big houses have big yards, so courts were often at least a hundred foot away. One needed a golf cart to get to.

Since this is high end, check out lighting systems from Lutron Electronics, Inc. - Dimmers And Lighting Controls (http://www.Lutron.com). Low voltage to the keypads. Lights direct to to controller.

I'd check these guys out too: www.amx.com