A Hydromassage bathtub, which is something you would find in a master bathroom, falls under section VII of article 680. Spas and Hot Tubs can be found in section IV of article 680 and there is a section for indoor and outdoor type tubs. Although code permits installing GFCI receptacles at the cord connection where the motor is, a more professional installation would be to install a faceless GFCI device above the switches in the room where it more convienent to the end user when the device trips and needs to be reset. I'd say close to 70% of homeowners wouldn't think to check inside their tubs for a tripped GFI.
