There seems to be some different interpretations as to the scope of OSHA-29 CFR 1910 Subpart S.
This subpart DOES NOT apply to all equipment that plugs into the AC mains. The Introduction specifically states 1910.301 (a) Design and safety standards for electrical systems These regulations are contained in 1910.302 through 1910.330. Sections 1910.302 through 1910.308 contain safety standards for electrical utilization systems. Included in this category are all electrical equipment and installations used to provide electric power and light for employee workplaces. Sections 1910.309 through 1910.330 are reserved for possible future safety standards for other electrical systems. Later in 1910.399 utilization systems are define as (128) A utilization system is a system which provides electric power and light for employee workplaces,and includes the premises wiring system and utilization equipment. utilization equipment is described just above this in 1910.399 (127) Utilization equipment means equipment which utilizes electric energy for mechanical, chemical, heating, lighting or similar useful purpose. This definition clearly does not cover a computer unless maybe it is used to control one of the elements above. The introduction specifically reserving 1910.309 through 1910.330 for other "electrical" systems indicates that there are other types of systems that do not fall under these standards. This specification is design to handle installations in the workplace, NOT the design of individual pieces equipment. The only electrical systems that need to be "approved" which is "acceptible" equipment as designated in 1910.399 (1) are those covered by this subpart which was described in the introduction and then redefined in 1910.399 (128). Engineers at our company have been "told" at seminars that UL or "approved" equipment was necessary to plug into the mains due to this CFR. This misinformation has led to alot of confusion and misdirected effort. Clearly there are state and local regulations that vary. I am not sure about the source of these regulations other than those specified in the NEC. It is definitely easier if the inspectors see a mark from an NRTL; however, I am not sure that it is actually required by the state and local regulations. This has only been a concern when our equipment was put into a new building that was under construction. It has seldom been an issue when the equipment (small rack mount equipment) was installed after the facility was built. Maybe the inspectors and the facilities engineers also have a different interpretation of the regulations. Jim Stafford HPS Product Engineer. (These comments do not necessarily reflect the views of my employer).
