A CIRCUIT BREAKER

摘要

A circuit breaker (1) includes an upper rail mounting device (26) defined by a line terminal (2) having a pair of spaced-apart jaws (31, 32). A bimetal (10) is adjusted by means of a calibration screw (12). An aperture (30) is provided in an upper sidewall portion (24a) of a base (20) of the circuit breaker for access to the screw (12) by a calibration device (35). The aperture (30) is positioned so that the calibration device (35) must pass through the jaws (31, 32) of the upper rail mounting device (26). This ensures that the calibration screw (12) can only be operated when the circuit breaker is disconnected from an electrical supply.