IEEE NESCIR546-2007 pdf download National Electrical Safety Code Committee, Accredited Standards Committee C2 National Electrical Safety Code ® Interpretation Section 11. Protective arrangements in electric supply stations
Rule 110B2 General requirements–Rooms and spaces–Use (2007 Edition, page 32)(30 March 2007)IR546
EXCEPTION 1 makes reference to equipment and EXCEPTION 2 and EXCEPTION 3 do not specifically mentionequipment. Can EXCEPTION 2 and EXCEPTION 3 be applied to equipment as well as materials? Also, it is not clearas to what type ofequipment is being considered under EXCEPTION 1.Would this apply to electrical equipment andconstruction equipment (line trucks, backhoes, trenchers,etc.)?
Discussion: Upon review of certain practices for storing materials and construction equipment in electricalsubstations, it was determined that some storage needs are short-term and some are long-term, lt is clear that longerm storage requires a separate fenced area. Clarification on the equipment considered under the exceptions wouloe very helpful in the setting of work practices such that they do not violate the Code
Interpretation
The Interpretations Subcommittee has considered the subject Interpretation Request for Rule 110B2 and hasdeveloped a consensus report as follows:
“Electric supply stations come in various forms and sizes. Small unit substations may have very few exposedhigh-voltage parts while larger substations and switching stations tend to have an abundance of high-voltagelines, bus bars, transformers, switchgear, etc. Property size and the amount of fencing installed at a specific sitealso vary. Fencing may be minimal, enclosing only the station vard–the electrified portion of the station–andmay or may not cover the entire property. On the other hand. a perimeter fence may be installed to cover a mucharger area. In such cases, the station yard may or may not be enclosed with additional switchyard fencing
The rationale for fencing (or walls, etc,) is covered in the first paragraph of Rule 110A1, which reads: “Roomsand spaces in which electric supply conductors or equipment are installed shall be so arranged with fencesscreens. partitions. or walls to form an enclosure as to limit the likelihood of entrance of unauthorized persons orinterference by them with equipment inside. Entrances not under observation of an authorized attendant shall bekept locked.(Emphasis added.) Rule 110B2 prohibits storage except as allowed in the exceptions.EXCEPTION 1 is limited to items essential for the maintenance of installed equipment at the specific station.EXCEPTION 2 applies to both short- and long-term storage and, as is stated in the discussion above, requires aseparate or intermediate fence. EXCEPTION 3 is limited to temporary storage of items to be used for work inprogress, and all of the itemized requirements in the exception must be met.
lypes of equipment and material that may be stored under any of the exceptions have not been detailed becausef the vast differences in stations. methods of operation, and maintenance requirements. There is no intent toexclude either electrical equipment (such as spare transformers) or mechanized construction equipment (such asline trucks, etc,) as long as the other provisions of the exceptions are followed. However, with respect to thisinterpretation, note that Rule 110A1 limits entrance to the station yard (the inner sanctum) to authorizedpersonnel and states that all entrances to such an area must be kept locked if not under the observation of anauthorized attendant. In other words, persons not qualified and authorized to be in station yards cannot delivermaterials or equipment to a yard nor can they park a truck in a yard unless under the observation of or escortedby a qualified and authorized person.
IEEE NESCIR546-2007 pdf download
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