Arc Flash Plasma – Modify the Arc Rating or Modify the Incident Energy Calculations?

Why Horizontal Electrode Configuration?

Although not the most common electrode configuration that is used when performing an arc flash study, using the Horizontal Conductors/Electrodes inside a metal box/enclosure (HCB) produces results that align closely with previous research from 2010.  That body of research explored the performance of some arc rated clothing when subjected directly to the convective flows of an arc flash. The conclusion was that the arc rating of PPE may need to be reduced when subject to the convective flows (from horizontal electrodes).

Fast forward and we find the 2018 Edition of IEEE 1584 – IEEE Guide for Performing Arc-Flash Hazard Calculations leads to a similar conclusion. Except rather than reducing the arc rating of the PPE, when incident energy calculations use the HCB electrode configuration, the result is a greater incident energy – which requires increasing in the arc rating.

In this video, Jim Phillips explains his findings by comparing the two methods.  The video is based on his presentation made at the 2020 IEEE Electrical Safety Workshop in Reno, NV