Section 39.235. Disconnection of fusible cut-outs before handling

(a) Fusible cut-outs in circuits operating at over 150 volts to ground, shall, if practicable, where accessible to others than qualified electrical attendants, be so arranged that the ungrounded current-carrying parts cannot be touched by persons refusing the cut-out until the fuses have been disconnected from all sources of electrical energy. If the circuit voltage exceeds 300 to ground, this arrangement shall always be made. If practicable this protection should also be provided for fusible cut-outs in curcuits operating below 150 volts to ground. This may be accomplished by a construction in which the fuse and its exposed current-carrying connections are accessible only after they have been disconnected from the circuit, either by opening the fuse enclosure or by other means.

(b) On circuits not exceeding 150 volts to ground, if the fusible cut-outs are not arranged so that they are necessarily disconnected from all sources of electrical energy before the ungrounded current-carrying parts can be touched, it is recommended that switches be so placed or arranged that opening them will disconnect the fuses from all sources of electrical energy. On circuits between 150 and 300 volts to ground, if fusible cut-outs are not arranged so that they are necessarily disconnected from sources of electrical energy before the ungrounded current-carrying parts can be touched, switches shall always be so placed or arranged that opening them will disconnect the fuses from sources of electrical energy unless portable insulating appliances are provided for handling the cut-outs.

(c) If fusible cut-outs are in locked cabinets or otherwise made inaccessible to all but qualified persons, sufficient protection is usually secured, even for voltages above 300, by the use of switches accessible only to such persons, these switches to be placed or arranged so that their operation will disconnect the fuses from all sources of electrical energy.