Electrical switches and circuit breakers in which the contacts and operating mechanism are enclosed within an insulating housing by an insulating cover and which have an elongated operating handle extending through an elongated slot in the cover have an enlarged terminal portion of the operating handle which is wider than the slot to prevent removal of the cover except in positions of the handle at which the electrical contacts are open and the slot is wider than the terminal portion of the handle. Preferably, this is only the OFF position of the switch or breaker, however, in circuit breakers with a notch at the trip position to expose indicia indicating the breaker operating condition, a transverse pin through the operating handle permitting removal of the cover only with the operating handle in the trip position, provides an economical backfit.