In my bathroom (shower, tub and no window) I have single switch which operates both the lights and the ventilation fan. I would like to turn this into a double switch, one which operates the lights and the other would operate the fan. I have been told this is against building code. I live in Boston, MA. Is this against building code? And, so I can be more self reliant in the future, where could I find building codes? Any help would be much appreciated.