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Electrical systems with AC voltage have been shown to exhibit arc flash incident energy during faults. Are there arc flash hazards related to dc systems, such as battery banks for UPS or drives, or dc buses used in chemical processes? Methods are available to estimate arc flash energy of ac exposures, but not dc. This paper will show the basic equations for maximum power from a dc arc and the resulting estimated arc flash incident energy. Research is required to find accurate values, but until research is completed, these equations can help the engineer provide a preliminary estimate of the thermal energy values for applying protective clothing for these exposures. [ABSTRACT FROM PUBLISHER]

The authors and their colleagues have used the methods in IEEE 1584 "Guide for Performing Arc Flash Hazard Calculations" to complete electrical hazard assessments for over 90 industrial sites, from small warehouse and office facilities to large chemical plants. This paper provides analysis of the results of those assessments, with an emphasis on the safety improvements that were made in design, work practices, and application of personal protective equipment. Modifying electrical equipment design, choosing good work practices, and applying sound engineering judgment can help to minimize arc flash hazard exposures and reduce costs due to injury and process downtime. [ABSTRACT FROM AUTHOR]

There have been recent advances in equipment de- sign and arc flash hazard assessment. It is possible to design a complete site electrical system, from transmission to distribution to utilization voltage, with the estimated arc flash energy below 20 cal/cm² (80 J/cm²) for all equipment. This paper describes a preferred design, where all workers can have proper arc flash personal protective equipment by using single-layer flame resistant everyday clothes and add a single-layer coverall for the higher energy tasks. Inherently safer design is in our future to reduce hazards and keep our workers safe. [ABSTRACT FROM AUTHOR]