Current through Register Vol. 54, No. 50, December 14, 2024
Section 39.254 - Guards for live parts(a) Motors operating at over 150 volts to ground, unless isolated by elevation at least 8 feet above the floor line, should, if practicable, be provided with permanent inclosures or other suitable guards so arranged as to prevent persons or conducting objects from inadvertently coming or being brought into contact with live parts or interfering with the operation of the motors.(b) Suitable insulating mats or platforms of substantial construction and providing good footing shall be so placed on floors and, if necessary, on frames of machines having exposed live parts above 150 volts to ground that the operators or other persons in the vicinity cannot readily touch such parts unless standing on the mats, platforms, or insulating floors. The suitable guarding of live parts by inclosures of barriers effective during attendance or necessary adjustments of live parts will obviate the necessity for insulating mats, and, if such mats are impracticable from the nature of the location or process carried on, guards shall be used. If connectors are used in motor leads, these should be provided with insulating covering equal to that on the conductors.(c) If necessary, steps and handrails shall be installed on or about large machines to afford safe access to live parts which shall be examined or adjusted during operation.(d) If two or more machines, either of which operates at over 150 volts to ground, are mechanically coupled together, and the operator can touch the frames of more than one at a time, the frames of all such machines shall be permanently grounded, unless they are bonded together electrically and surrounded by insulating mats or platforms on which it is necessary persons stand in order to touch the machine frames. If operating at above 300 volts to ground, their frames shall always be grounded, and frames shall also be grounded wherever, from the nature of the location or of processes carried on, the use or maintenance of insulating mats or platforms is impracticable. Reference should also be made to § 39.197(c) (relating to grounding).