Section 39.113. Guards for live parts

(a) Suitable insulating mats or platforms of substantial construction providing good footing shall be placed on floors and, if necessary, on frames of machines having exposed live parts above 300 volts to ground, so that no operator may readily touch such parts unless he is standing on the mat or platform.

(b) For parts above 750 volts, suitable enclosing or barrier guards shall, if practicable, be provided in addition to mats or platforms, and arranged such that the operator may not inadvertently touch the live parts and any neighboring grounded parts at the same time.

(c) If necessary, steps and handrails shall be installed on or about large machines to afford ready access to live parts which shall be examined or adjusted during operation.

(d) If switches are installed on the frames of generating equipment for the purpose of reducing inductive voltage in generator and converter field coils, they shall be suitably constructed or guarded to prevent passers by from inadvertently coming in contact with the live parts, to protect persons handling them, and to prevent them being accidentally opened or closed.

(e) Suitable shields or barriers shall be provided where necessary to prevent areas from large commutators or circuit breakers from injuring persons in the vicinity such as narrow switchboard galleries or similar working spaces located immediately above or beside such equipment.