Section 43.37. Fuses, circuit breakers, switches, and motors

(a) Fuses and automatic circuit breakers shall be constructed so as to effectually interrupt the current when a short circuit occurs or when the current through them exceeds a predetermined value. No open type or link fuses shall be kept.

(b) All points at which a circuit has to be made or broken shall be provided with suitable switches, which shall be installed so that they cannot be closed by gravity.

(c) Fuses shall be stamped or marked, or shall have a label attached indicating the maximum current that they are intended to carry. Fuses shall be adjusted or replaced only by an authorized and competent person.

(d) The capacity of fuses used to protect feeders shall not exceed the current capacity of the feeder by more than 25%.

(e) All circuit breakers and fuses shall have noncombustible bases and shall be properly enclosed.

(f) All switches used for medium and high voltage shall have noncombustible bases and shall be of approved safety types.

(g) Every motor and its starting device shall be protected by a fuse in each phase or in the case of motors of more than 40 horsepower, by a circuit breaking device on at least one phase of direct current motors and on each phase of alternating current motors and by switches arranged to cut off entirely the power from the motor. These devices shall be installed in a convenient position near the motor and in sight of it.