Thus, a revised requirement in Art. 130 spells out more clearly how switchboards, panelboards, control panels, and like equipment must be labeled with critical information needed to gauge and mitigate potential risks and hazards. Now, a label must include nominal system voltage and the arc flash boundary, as well as at least one of the following: available incident energy level, minimum arc rating of clothing, required level of PPE, or highest hazard/risk category for the equipment.

“Many of the arc flash equipment labels installed today are incorrect because they include both an incident energy level and an HRC level, which can be confusing since only one method should be used,” Ayer says.

According to McCauley, the new, more definitive labeling requirement reflects the reality that accurate risk and hazard assessment on different equipment in different settings can be challenging. That’s a problem compounded by 70E’s historic allowance of numerous calculation methods that would benefit from greater clarity and specificity.

“In the past, the practice was to put incident energy information on the label, but the reality is that can change all the time depending on the configuration of a plant’s systems,” he says. “Something may be classified as, say, a Category 3, but there’s a range on that.”

Because accurate and reliable labels depend on precise engineering assessments of equipment, which over time can fall into disrepair that might render original calculations inaccurate, the 2012 edition codifies the importance of maintenance. Specifically, new language in Art. 205 states that to minimize the risk of failure and exposure to hazards, electrical equipment must be maintained in accordance with manufacturers’ instructions or industry consensus standards.

Committee member Ron Widup, president of Shermco Industries, a Dallas electrical power system testing company, says the new, pointed reference to a maintenance standard is evidence of growing recognition in the industry that worker safety is a function of proper maintenance.

“Calculation of incident energy exposure and specification of the proper PPE is premised on an engineering analysis either IEEE 1584 or 70E guidance, and it’s all based on the assumption that the relay, fuse, or circuit breaker has been installed and maintained properly,” Widup says. “But if an overcurrent protective device or panel hasn’t been tested in years, you have to ask yourself what the chance of the arc flash hazard analysis label on the equipment being accurate is. Over the next few cycles of 70E revisions, I think we’re going to see more focus on the maintenance aspect because it’s key to the validation of the engineering assessments designed to protect workers.”             

Zind is a freelance writer based in Lee’s Summit, Mo. He can be reached at