Arcing ground faults are common on 480Y/277V, 3-phase, 4-wire electrical systems. Arcing ground faults can be caused by human error when working around electrical equipment. When this happens, the results can be devastating. Arcing ground faults, arc flashes, and arc blasts produce high temperatures, high pressures, and acoustic and light energy that can severely injure workers. A large portion of NFPA 70E, Standard for Electrical Safety in the Workplace, is devoted to identifying these hazards and protecting workers from arc flash injuries.
Another cause of arcing ground faults is lack of recommended electrical equipment maintenance. These arcing events typically occur when no one is present. Different types of electrical equipment require different maintenance procedures and frequencies based on the manufacturer’s instructions. Additional guidance for electrical equipment maintenance is available from NFPA 70B, Recommended Practice for Electrical Equipment Maintenance and NETA-MTS, Standard for Maintenance Testing Specifications for Electrical Power Equipment and System.
Unfortunately, many building owners and property managers are not aware of these maintenance requirements and continue to operate electrical equipment in a “set-it-and-forget-it” scenario. This photo gallery is a sampling of electrical equipment that was operated this way, resulting in major equipment losses and long business interruptions. If you are not performing the recommended maintenance on your electrical equipment, now is the time to take action and set up a comprehensive electrical equipment maintenance program.
John Weber is principal electrical engineer for HSB-Hartford Steam Boiler in Hartford, Conn.
