Abstract: Apparatus and method for automatic control of with a high pressure mercury arc lamp is described. The apparatus includes a control unit that monitors the current and the voltage supplied to the arc lamp. A temperature measuring device is coupled to a portion of the lamp for monitoring the temperature. The control device controls a flow of air past the lamp by controlling the power to a fan motor or by controlling the flow of air by controllable dampers. After equilibrium conditions are established, the control unit determines and stores the equilibrium values of current and voltage. Thereafter the control unit monitors the values of current and voltage periodically. When these measured voltage and current values are outside of predetermined limits, the control unit initiates shut down operation of the lamp.