Arc flash studies and their accompanying labels are one of the backbones of electrical job safety planning and safe work execution. Both items give service personnel and equipment owners a starting point to plan work that involves shock hazards, arc flash hazards, or both. The 2009 edition of NFPA 70E provided the criteria for shock and arc flash boundaries and requirements for personal protective equipment. That edition also specified rules for reviewing and updating arc flash studies and their associated labels.
Since then, the NFPA has continued to refine these requirements. It has provided updated guidelines on calculation methods and worked with IEEE on Standard 1584 to provide equipment owners and those employees servicing electrical equipment with more accurate calculations. The continued development of the standard has contributed to a decrease over time in electrical injuries and fatalities.
Biggest Arc Flash Study Misconception
The 2024 NFPA 70E standard indicates that personnel whose duties involve operating and servicing electrical equipment shall perform a shock risk assessment and an arc flash risk assessment as part of the pre-task job planning and PPE selection process. This connects to OSHA 29 CFR 1910.132(d)(1), which states, “The employer must assess the workplace to determine if hazards are present or are likely to be present. If those hazards necessitate the use of PPE, the employer must select and have the affected employee use PPE that fits, as well as communicate selection decisions to the affected employee.” One of the ways these hazards are communicated is through an incident energy analysis, also known as an arc flash study, which is subsequently displayed on an arc flash label.
Many people, in reading through the NFPA 70E, see the notation about revisiting an arc flash study every five years and jump to the conclusion that the entire study must be recalculated on that interval. This is the biggest arc flash study misconception because it is only partially correct. The 2024 NFPA 70E specifically states that “an incident energy analysis shall be reviewed for accuracy every five years.” It also mentions that “the incident energy analysis shall be updated when changes occur in the electrical distribution system that could affect the results of the analysis.” There is a clear distinction from the NFPA for when a study needs to be reviewed and when part or all of it needs to be recalculated.
First, let’s discuss updating an incident energy analysis. Some items that can trigger the need for an updated arc flash study include changes to physical apparatus such as transformers, cables, or distribution equipment, modifications to protective devices or device settings, or changes made by utilities in the service to the facility. Any such change requires the recalculation of the circuits affected by those changes and the application of updated labels. Sometimes these changes result in significant recalculations and other times they are relatively minor. These updates should ideally be completed at the time of equipment or service modification, but definitely within the five-year review period.
It is imperative that employers inform personnel of hazards they are exposed to. Any delay in updating this information leaves employees vulnerable to making inadequate PPE selections and choosing the wrong work methods based on incorrect information. For example, if upon recalculation, the available incident energy at a device increases from 38 cal/cm2 to 45 cal/cm2, there will need to be significant changes to the processes and procedures used when servicing or operating that equipment.
Next, let’s discuss the review of an arc flash study. The 2024 NFPA 70E states, “the data to support the information for the label shall be reviewed for accuracy at intervals not to exceed five years.” This review must be documented, and records of this documentation must be maintained. A review must occur every five years and the historical confirmation of the review needs to be maintained by the equipment owner. As mentioned above, any changes and their associated recalculations must be incorporated into the records kept by the equipment owner and new labels applied where the changes occurred.
It is also important to note that “labels applied prior to the effective date of the current edition of the standard shall be acceptable if they complied with the requirements for equipment labeling in the standard in effect at the time the labels were applied.” It is a common misconception that all the labeling in a facility be replaced at the five-year interval. The NFPA specifically allows existing labels to remain in place. That being said, there are times when it may be prudent to consider recalculating the available incident energy at specific devices within a distribution system, even if no changes were made in the last five-year period.
Be Aware of Standard Updates
One example of this is the enhanced calculation parameter within IEEE 1584 that now considers enclosures of different depths and conductor configurations. If an equipment owner, for example, has an existing higher amperage item that is housed in a shallow enclosure, such as a 480 V, 2000 A disconnect, there is now the likelihood of a higher arc flash hazard result with the newer formulas. Providing employees with this enhanced information is a good reason to update parts of the study and apply new labels outside of the standard label requirements where applicable.
There is an additional consideration for the installation of new labels. Any time that labels have become hard to read or are damaged by the environmental conditions, they should be replaced so that the correct information is available to workers who examine, service, maintain, or operate that equipment. Not having proper information at hand can lead to incorrect assumptions by employees.
In approaching arc flash studies and the guidelines associated with them, it is important that trained and qualified individuals assist equipment owners in staying informed on their responsibilities, reviewing and documenting their system information, and supporting them by providing accurate, updated information when changes to their systems occur. It is just as important that equipment owners be proactive in the documentation of the electrical hazards in their facilities. The commitment to safety through quality information, documentation, and procedures will continue to enhance safer work environments and also continue the downward trend of electrical injuries and fatalities in the workplace.
Author Denise Green is the Midwest regional sales manager and national breaker specialist for Group CBS and has been in the electrical distribution industry for more than 30 years.
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