All shower compartments and shower-bath combinations shall be provided with an automatic safety water mixing device to prevent sudden unanticipated changes in water temperature or excessive water temperatures. The automatic safety water mixing device shall be either thermostatic, pressure balance, or combination controlled, in accordance with ANSI/ASSE 1016-1990, and designed with a maximum handle rotation limit/stop, adjusted to a maximum setting of 115°F (46.1°C) at the time of installation. The temperature of mixed water provided to multi-shower units or gang showers shall be controlled by a master automatic safety water mixing device or the mixed water temperature for such showers shall be individually regulated by automatic safety mixing valves for each shower unit. A hot water heater thermostat shall not be an acceptable alternative water temperature control device.