30 CFR § 77.900-1
Testing, examination, and maintenance of circuit breakers; procedures.
Circuit breakers protecting low- and medium-voltage circuits serving portable
or mobile three-phase alternating current equipment and their auxiliary
devices shall be tested and examined at least once each month by a person
qualified as provided in §77.103
. In performing such
tests, the circuit breaker auxiliaries or control circuits shall be actuated
in any manner which causes the circuit breaker to open. All components of the
circuit breaker and its auxiliary devices shall be visually examined and such
repairs or adjustments as are indicated by such tests and examinations shall
be carried out immediately.