IEEE TRANSACTIONS ONINDUSTRY APPLICATIONS, VOL. 56, NO. 6, NOVEMBER/DECEMBER 2020 6307 Determine the Electrode Conﬁguration and Sensitivity of the Enclosure Dimensions When Performing Arc Flash Analysis Kaynat Zia , Student Member, IEEE, Anusha Papasani , Student Member, IEEE, David Rosewater , Senior Member, IEEE, and Wei-Jen Lee , Fellow, IEEE Abstract—Arc ﬂash hazard prediction methods have become more sophisticated because the knowledge about arc ﬂash phe- nomenon has advanced since the publication of IEEE Std. 1584- 2002. The IEEE Std. 1584-2018 has added parameters for more accurate arc ﬂash incident energy (IE), arcing current, and protec- tion boundary estimation. The parameters in the updated estima- tion models include electrode conﬁguration, open circuit voltage, bolted fault current, arc duration, gap width, working distance, and enclosure dimension. The sensitivity and effect changes of other parameters have been discussed in the previous literatures. This article explains the fundamental theory on the selection of electrode conﬁgurations and performs sensitivity analysis of the enclosure dimension that have been introduced in the IEEE Std. 1584-2018. According to the newly published model for IE estima- tion, the IE between vertical conductors inside a metal box (VCB) and horizontal conductors inside a metal box (HCB) can differ by a factor of two with other parameter constants. Using HCB as the worst-case scenario to determine the personal protection requirements may not be the best practice in all circumstances. This article provides guidance for electrode conﬁguration selection and a sensitivity analysis for determining a reasonable engineering margin when actual dimension is not available. Index Terms—Arc ﬂash, electrode conﬁguration, enclosure dimensions, incident energy (IE), plasma trajectory. I. INTRODUCTION A N ELECTRIC arc is formed when two physically sep- arated and energized conducting bodies transfer charge through air [21]. Manuscript received February 27, 2020; accepted July 3, 2020. Date of publication August 31, 2020; date of current version November 19, 2020. Paper 2020-PSPC-0282, presented at the 2020 IEEE/IAS 56th Industrial and Commercial Power Systems Technical Conference, Las Vegas, NV, USA, Apr. 27–30, and approved for publication in the IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS by the Power Systems Protection Committee of the IEEE Industry Applications Society. This work was supported in part by the U.S. Department of Energy, Ofﬁce of Electricity, Energy Storage Program. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government. (SAND2020-7245 J). (Corresponding author: Kaynat Zia.) Kaynat Zia, Anusha Papasani, and Wei-Jen Lee are with the Electrical Engi- neering, University of Texas at Arlington, Arlington, TX 76019 USA (e-mail: kaynat.zia@mavs.uta.edu; anusha.papasani@mavs.uta.edu; wlee@uta.edu). David Rosewater is with the Sandia National Laboratories, Albuquerque, NM 87123 USA (e-mail: dmrose@sandia.gov). Color versions of one or more of the ﬁgures in this article are available online at https://ieeexplore.ieee.org. Digital Object Identiﬁer 10.1109/TIA.2020.3020531 The loss of insulation between conductors, due to aging; environmental factors; human errors; and overheating, is one of the main causes of the electric arc formation [3]. The current ﬂowing ionizes the air between the conductors, while converting it into plasma and causing a rapid increase in temperature. The plasma is responsible for giving the arc its characteristic “ﬂash” and contains the biggest part of the arc energy [20]. The high temperature, often compared to the temperature of the surface of the sun [16], brings about melting and evaporation of the conductors and other materials in the vicinity. This further increases pressure and temperature of the area near the arc. If the arc is not extinguished, the mounting pressure and temperature leads to an explosion. Severed equipment and molten debris move outward during this explosion, while burning and striking everything around it [14]. An arc starts with a series of transitions signiﬁed by their ap- pearance in high speed ﬁlm. The glow to arc transition starts with the “dark discharge” [5] or Townsend discharge [13], where elec- tric ﬁeld accelerated free electrons collide with gas molecules and as a result free more electrons; this causes an exponential increase in current versus voltage, due to the rapid ionization of air. The dark discharge stage is followed by “glow discharge,” where voltage drops suddenly as current increases. The ﬁnal stage involves the release of large number of electrons from the cathode [6]. The energy released during the arc is transferred through radiation, convection, and conduction. The hazard of an arc ﬂash to humans is proportional to the temperature rise of skin due to the absorption of the released energy. If the energy absorbed by the human skin exceeds 1.2 cal/cm 2 [4], [18], it can cause second degree burns, according to the experiments conducted by Dr. Alice Stoll. Incident energy (IE) is used to quantify the energy incident on the surfaces, equipment, or human, near the arc ﬂash. It is the area under the curve of the rate of heat transfer to a certain working distance, over time. By limiting the IE, personnel injury and equipment damage can be prevented. Electrode conﬁguration can be a compounding factor for IE because the shape of the plasma explosion is not necessarily spherical. Right after arc initiation, a rapid increase in tempera- ture causes the expansion of the hot air/plasma and can push the trajectory of the plasma to a direction governed by the orientation of the electrodes. According to IEEE Std. 1584-2018 [1], an electric arc originating in horizontal conductors inside a metal This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/