Practical methods in reducing the dangerous arc flash hazard areas in large industrial facilities

Industrial and commercial facilities have recognized that arc flash prevention is a part of a complete safety program. Quantification of the arc flash hazard level and labeling procedures are a major portion of this effort. When calculating incident energy, the engineer must deal with two main issues in addition to the burn hazard-blast pressure effect on the human body and worker comfort or mobility with multilayer flash suits and associated flame resistant protective equipment. For work tasks where calculated incident energy levels are above 40 cal/cm², it is desirable to reduce the exposure to the worker to reduce the burn injury. This can be achieved with either a change to the work method or by engineering design. This paper will discuss various methods that have been used to reduce the incident energy levels from above 40 cal/cm² to levels below 40 cal/cm ². Specific solutions implemented at a large chemical manufacturing facility are presented. The solutions include equipment upgrades, overcurrent protection modifications, changes to work methods, and worker training which increase the effectiveness of an already robust safety program. In addition, design changes that could be considered to keep incident energy below 40 cal/cm₂ for expansions or additions to the power system are discussed