Enhancing Worker and Equipment Protection Through Passive Arc-Fault Mitigation

Existing arc flash standards like IEEE 1584 and 1584.1 present models that can be used to estimate incident energy levels in power distribution equipment but provide limited direction regarding how equipment construction should be considered in the calculations. Users performing arc flash risk assessments are left to apply engineering judgment when considering how barriers or isolation of components should be considered. This can lead to risk assessments that are inconsistent or incorrect. Current practices regarding arc flash evaluation in barriered and nonbarriered equipment are reviewed based on current standards. Gaps and potential concerns are discussed, including the lack of defined criteria to use in calculations, along with lack of criteria for determining when barrier systems are considered effective at preventing, mitigating, controlling, or containing arcing faults. A description of a new system that provides passive protection in low-voltage distribution equipment is presented. By providing improved protection for the incoming conductors and main circuit breaker itself, this line-side protection system reduces or eliminates the uncertainties, which allows for more consistent and accurate application of risk assessments. The new protection system enables arc flash protection to be provided by a passive, enclosed system that has been tested to verify performance. As such, the calculations and risk assessment are less reliant on assumptions regarding the performance of the equipment. Practical aspects of arc flash analysis and labeling and operation and maintenance of such equipment are also discussed.