30 CFR § 75.900
Low- and medium-voltage circuits serving three-phase alternating current equipment; circuit breakers.
Low- and medium-voltage power circuits serving three-phase alternating
current equipment shall be protected by suitable circuit breakers of adequate
interrupting capacity which are properly tested and maintained as prescribed
by the Secretary. Such breakers shall be equipped with devices to provide
protection against undervoltage, grounded phase, short circuit, and