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Report on High Energy Arcing Fault Experiments - Experimental Results from Low Voltage Switchgear Enclosures



Gabriel Taylor, Anthony D. Putorti Jr., Scott Bareham, Christopher U. Brown, Wai Cheong Tam, Edward Hnetkovsky, Andre Thompson, Michael Selepak, Philip Deardorff, Kenneth Hamburger, Nicholas Melly, Kenneth Miller


This report documents an experimental program designed to investigate High Energy Arcing Fault (HEAF) phenomena for low-voltage metal enclosed switchgear containing aluminum conductors. This report covers full-scale laboratory experiments using representative nuclear power plant (NPP) three-phase electrical equipment. Electrical, thermal, and pressure data were recorded for each experiment and documented in this report. This report covers experiments performed on two low-voltage switchgear units with each unit consisting of two vertical sections. The data collected supports characterization of the low-voltage HEAF hazard, and these results will be used to support potential improvements in fire probabilistic risk assessment (PRA) methods. The experiments were performed at KEMA Labs located in Chalfont, Pennsylvania. The experimental design, setup, and execution were completed by staff from the NRC, the National Institute of Standards and Technology (NIST), Sandia National Laboratories (SNL) and KEMA. In addition, representatives from the Electric Power Research Institute (EPRI) observed some of the experimental setup and execution. The HEAF experiments were performed between August 26 and August 29, 2019 on near-identical Westinghouse Type DS low-voltage metal-enclosed indoor switchgear. The three-phase arcing fault was initiated on the aluminum main bus or in select cases on the copper bus stabs near the breaker. These experiments used either nominal 480 V (AC) or 600 V (AC). Durations of the experiments ranged from approximately 0.4 s to 8.3 s with fault currents ranging from approximately 9.2 kA to 19.3 kA. Real-time electrical operating conditions, including voltage, current, and frequency, were measured during the experiments. Heat fluxes and incident energies were measured with plate thermometers, radiometers, and slug calorimeters at various locations around the electrical enclosures. Environmental measurements of breakdown, conductivity, and electromagnetics were also taken. The experiments were documented with normal and high-speed videography, infrared imaging, and photography. The results, while limited, indicated the difficulty in maintaining and sustaining low-voltage arcs on aluminum components of sufficient duration and at a single point as observed from operating experience.
Technical Note (NIST TN) - 2197
Report Number


High Energy Arcing Fault, Arc Flash, Electrical Enclosure, Electric Arc, Fire Probabilistic Risk Assessment


Taylor, G. , Putorti Jr., A. , Bareham, S. , Brown, C. , Tam, W. , Hnetkovsky, E. , Thompson, A. , Selepak, M. , Deardorff, P. , Hamburger, K. , Melly, N. and Miller, K. (2021), Report on High Energy Arcing Fault Experiments - Experimental Results from Low Voltage Switchgear Enclosures, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online],, (Accessed May 30, 2024)


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Created December 29, 2021, Updated November 29, 2022