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NFPA 70E®-2009 Standard for Electrical Safety in the Workplace® TIA Log No.: 981 Reference: 130.3, Exception No. 1 Comment Closing Date: February 1, 2010 Submitter: Daleep Mohla, DCM Electrical Consulting Services, Inc. 1. Delete Exception No. 1 to Section 130.3, Arc Flash Hazard Analysis, which presently reads as follows: Exception No. 1: An arc flash hazard analysis shall not be required where all of the following conditions exist: (1) The circuit is rated 240 volts or less. (2) The circuit is supplied by one transformer. (3) The transformer supplying the circuit is rated less than 125 kVA. 2. Renumber Exception No. 2 as Exception. SUBSTANTIATION: Safety Concern Article 130.3, Exception No. 1 can lead to incorrect conclusions and an unsafe condition for workers expected to perform work on the equipment and needs to be immediately removed. Using this exception as written and not properly analyzing the hazard can result in a potential injury to the workers if hazard due to a potential arc flash is not addressed properly. A. Incorrect Substantiation The text of Section 130.3, Exception No. 1 was supposed to be based on IEEE 1584-2002. It was incorrectly transcribed. In addition, the text placed in the existing Exception No. 1 is only a portion of the text in IEEE 1584-2002 related to this subject and was taken out of context. Without providing the proper context and balance of the critical information contained in IEEE 1584-2002, the exception is incorrect. 1. There are a number of inconsistencies and errors in this text, scope and purpose of IEEE 1584- 2002 which clearly states that single phase systems are not included in this guide. 2. Exception No. 1 as currently written applies to all systems (three phase and single phase) rated 240 volts and below. 3. This exception is applicable to all enclosure sizes which is not consistent with IEEE -1584. IEEE 1584- 2002 clearly states hazards in smaller enclosures, including equipment such as panel boards, voltages as low as 208 volts can cause severe injuries. IEEE 1584-2002, 9.3.2 in part states "Arc faults can be sustained at 208 V and have caused severe injuries with very high short-circuit current applications in meter enclosures. A meter enclosure is small and tends to confine an arc more than laboratory test boxes with no door. Used equipment at 208 V was not tested, but it is recognized that many types of equipment have relatively small open spaces between components, such as the space in a panelboard between the circuit breakers and the wall of the enclosure. B. Conflict with NFPA 70E-2009 1. Conflict with Table 130.7(C) (9) The existing text in Section 130.3, Exception No. 1 is also in direct conflict with recommendations contained in NFPA 70E-2009 Table 130.7(C)(9), Hazard Risk Category Classifications and Use of

Rubber Insulating Gloves and Insulating Hand Tools, which states that for "Panelboards or Other Equipment Rated 240 V and Below" in certain situations the equipment should be classified HRC-1, indicating an arc flash hazard level of up to 4 cal/cm2. 2. Hazard Risk Analysis There are many conditions and installation parameters that affect whether or not an arc flash hazard exists, and if so how to "accurately" predict it. Without analysis by competent people using good engineering judgment, a good prediction of the hazard cannot be made. The existing text of Article 130.3, Exception No. 1, or any other text, does not cover all conditions and installations that may exist. Any exception wording, including the existing text, is going to be a source of confusion, inconsistency, and a potentially dangerous situation for the reader. This exception has created confusion within the industry relative to how it should be applied and opens the door for potential misapplication. The existing exception deals with the 240 volt and below, and below 125 kVA issue. A number of other situations in a typical power distribution system, if subject to similar text, would also create the potential for confusion and misapplication. C. Technical Error Arc Flash Hazard is proportional to bolted fault current and fault clearing time. Fault current from a transformer cannot be calculated based only on kVA To calculate bolted fault from a transformer, impedance of the transformer and available fault current on the primary of the transformer is needed. This exception is based on transformer kVA with no mention of impedance or available primary fault current.. To calculate arc flash, bolted fault current and fault clearing time are both required. Arc Flash cannot be calculated only based on transformer kVA. Fault clearing time is not mentioned in the text of the present 130.3 Exception No.1. D. Hazard Risk Analysis Substantiation for this exception does not exist. The words "an arc flash hazard analysis shall not be required" in 130.3 Exception No. 1 are being interpreted as meaning that there is no arc flash hazard associated with this equipment under any condition. This is simply not true. IEEE 1584- 2002 clearly identified depending on the enclosure size, and even systems at 208 volts can result in Arc Flash hazard. IEEE 1584-2002, 9.3.2 in part states "Arc faults can be sustained at 208 V and have caused severe injuries with very high short-circuit current applications in meter enclosures." A meter enclosure is small and tends to confine an arc more than laboratory test boxes with no door. Used equipment at 208 V was not tested, but it is recognized that many types of equipment have relatively small open spaces between components, such as the space in a panelboard between the circuit breakers and the wall of the enclosure. The hazard may be determined to be high, or low, but an analysis of the potential for arc flash hazards must be done to perform Hazard/Risk Analysis. The working distance for this type of equipment is typically much less than for higher voltages/capacity circuits which would, of course, increase any arc flash hazard that may be present. Working distances assumed to be in the range typical for higher voltages, 18" for example, will result in much lower incident energy levels, falsely giving the person working on this type of equipment at a distance of 6" the impression there is no, or a much reduced hazard, than actually is present. An analysis must be done of all potential hazards. Decision needs to be made by owner of the equipment with proper hazard risk analysis to determine the extent of the possible hazard and protective equipment and measures required to mitigate the hazard. To say definitively that equipment belonging to a particular class does not pose a risk in any situation is dangerous and should not be included in NFPA 70E. The 70E document requires an analysis of all hazards be done for all work to be performed prior to exposing people to any potential hazards.

EMERGENCY NATURE: This proposed TIA is of an emergency nature because the broad application of this this exception has the potential to expose personnel to arc flash hazard in some 240 volt and under applications. The existing text of Article 130.3, Exception No.1 is a consistent source of confusion and has a high potential for misapplication of the requirements of NFPA 70E-2009. The text placed in the existing Exception No. 1 was taken from IEEE 1584-2002 and is only a portion of the text in IEEE 1584-2002 related to this subject. Taken as written, without the benefit of the balance of the discussion in IEEE 1584-2002, the reader of Article 130.3, Exception No. 1 can be lead to incorrect conclusions and is subjected to a source of confusion. This confusion and potential misapplication can lead to incorrect arc flash hazards analysis results and in the workers exposed being underprotected. This proposed change should be implemented at this time because the next revision to the NFPA 70E document will not be issued until late 2012. Without this TIA, this source of confusion, potential misapplication will exist until the document is revised. The risk of workers being underprotected from arc flash hazards present with this equipment will exist until this requirement is corrected.

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