An electric fluid heater includes a metallic container defining a heating chamber provided with a pair electrodes for passing electric current through the fluid for heating the fluid. The container has a fluid input port, a fluid output port and a safety port all communicating with the heating chamber. The ports have a reduced aperture portion of a substantial length to increase the resistance of the current leakage path from the electrodes to external ground connections. All surfaces of the metallic container including the fluid contacting surfaces of the heating chamber and ports are covered by an electrically insulative coating. An external pressure relief valve is connected to the safety port.