As John said, there are no requirements for residential. For commercial, you might want to take a look in the "building code for electricians" section in this site, as it has quite a lot of information.
Basically, you want to mount 15" to 48" for everything, as that is the standard reach range. The ADAAG (ADA) allows an unobstructed side reach of 54", but bare in mind that many states do not use the ADAAG for accessilbilty, but rather the ANSI A117.1. The ANSI doesn't recognize the 54" clearance, except for in existing buildings
Ryan Jackson, Salt Lake City
Re: Switch Elevation Standards#44820 11/12/0412:45 AM11/12/0412:45 AM