An electric water heater tank adapted for connection to a controller, the tank including one or more electrical heating elements temperature sensing means mounted on the exterior of the tank wall and adapted to obtain a measurement of the temperature of the water in the tank, the temperature sensing means and each heating element being connected to an externally accessible connection means. The tank can include one or more heating element control means each connected to a corresponding one of the heating elements. The element control means can be connected to the externally accessible connection means.