Recent Arc Flash Updates to NFPA 70E & The NEC


This blog post was written by Jason Wyenberg.

Ensure you’ve got the latest updates for your Arc Flash requirements.

Arc flash standards are a relatively new addition to the National Electric Code (NEC) and NFPA 70E “Standard for Electrical Safety in the Workplace.” The standard calculation method for performing arc flash studies (IEEE 1584) was only introduced in 2002. Manufacturers are still developing new, more sophisticated methods of mitigating arc flash hazards in electrical equipment. Facility operators are still refining their safety programs to train employees. Code authors are taking note and have made several revisions in recent code updates.

One update to the 2014 NEC was to change the wording of article 240.87 addressing arc flash energy reduction features of large breakers. Any breaker 1200A or larger must now be provided with a Reduced Energy Let-Through (RELT) feature as listed in the code.

Some of the more significant changes in the 2015 NFPA 70E update include elimination of the “Prohibited Approach Boundary,” and renaming of the term “Hazard/Risk Category” to “PPE Category” to describe the level of PPE to be used when working in the arc flash hazard boundary. Along with this verbiage change, the Category 0 arc flash hazard level has been removed and replaced with the statement: “No Arc Flash PPE Required.” Rather than describing a Category 0 level of Arc Flash PPE, a description of standard safety equipment is listed.

How should you deal with these changes? NFPA 70E recommends that an arc flash study be updated every 5 years to account for changes to the facility’s and utility’s distribution systems. If your facility has recently completed an arc flash study, you may be concerned to hear that the NFPA 70E 2015 standards affect the content of your report and the labels installed on electrical distribution equipment. An update to the 2015 standard is not required immediately. It is appropriate to wait until the next 5-year update to incorporate the NFPA 70E changes into your arc flash study. Consider the two updates listed above. If a study was performed under the 2012 standard, a Category 0 designation would have been applied to some equipment. Per the 2015 standard, labeling a PPE category on this equipment would be overly conservative. Some facility owners, after updating their arc flash standards to the 2015 version, have even elected to keep the Category 0 PPE designation in order to remain consistent with past training and conservative with the arc flash hazard labeling. Similarly, having equipment labeled with the Prohibited Approach Boundary shows an extra level of caution for the shock hazard risk of electrical equipment.

To meet the requirements of NEC 240.87, ensure that your vendor is providing an RELT feature on any new breaker 1200A or larger. A simple method is to install a maintenance safety switch, which will lower the breaker settings to their minimum when operated. This switch can be specified to be installed on the breaker or remote from the breaker. New distribution equipment may also be specified with other RELT features such as zone-selective interlocking, differential relaying, or photo-eye arc flash detection.