A Detailed Approach for ARC Flash Sustainability for Systems at or Below 240V and Over 2000A

Abstract

The IEEE Std. 1584–2018 IEEE Guide for Performing Arc Flash Hazard Calculations has seen a welcome improvement in calculation accuracy from the 2002 version. Empirical data used for the 2018 standard shows that below 250VAC certain arcs sustained while other arcs failed to sustain. The “<240V and <125kVA transformer” exception in the 2002 standard has been replaced by “≤240V (nominal) and <2000A (short-circuit current)” language, that includes a band of arcs that did not sustain during practical testing. Previously published papers suggested further research into this area, however, within the finite resources available to the 1584–2018 working committee, not all requests could materialize. This paper investigates whether guidelines for arc sustainability (<250VAC equipment) match the empirical arc testing data available from IEEE, the Electric Power Research Institute (EPRI), and others while considering new developments and a better understating of arc physics. It uses recent data from studies performed at utilities and industry to determine the impact (if any) of a range of conservatism in the standard. This paper concludes by presenting a more detailed approach using NFPA 70E® - 2021 for users who may be affected by conservative results and suggests areas where additional testing and research may benefit end-users.