Abstract: A three phase hermetic protector for electrical apparatus has a pair of terminals extending through a header with first and second elongated heaters mounted on the terminals and extending away from the header. A rigid support is attached to the header between the terminals and extends away from the header and mounts a third elongated heater extending back toward the header. A snap acting disc is cantilever mounted on the free end of the third heater and mounts thereon a pair of movable contacts adapted to move into and out of the engagement with stationary contacts mounted at the free ends of the first and second heaters. The rigid support mounts a calibration screw beneath the free end of each of the first and second heaters to independently adjust the vertical position of the stationary contacts.