![]() ![]() Limited and Restricted Approach boundaries deal with shock and are determined by NFPA 70E Tables 130.4(C)(a) for AC systems and 130.4(C)(b) for DC systems, while Arc Flash boundaries are determined through an Arc Flash Analysis or through the use of the use of the Arc Flash PPE Categories in 130.7(C)(15)(a). As part of a larger training and safety program, these boundaries are put in place to minimize risk through avoidance or the use of PPE. These boundaries trigger multiple requirements in 70E including but not limited to determining the type and level of PPE and qualifications required to cross into each level. Alerting people to the presence of the boundary will allow them to take proper precautions and help contribute to the overall safety of the entire facility.Under NFPA 70E, there are three boundaries that are observed-limited approach, restricted approach, (the shock protection boundaries) and arc flash boundary. This is typically done with floor marking tape as well as wall signs or labels. Once the arc flash boundary has been identified, facilities should make it clear so that those working or visiting the area will be able to spot it. By wearing proper PPE on either side of the boundary, those in the area can properly respond to an emergency, which will help to keep the facility safe. Even outside the arc flash boundary it is a good idea to at least wear basic PPE to avoid any type of injury. This will also let them know where they should begin wearing different levels of personal protection equipment. ![]() The most obvious benefit of an arc flash boundary is, as mentioned above, that people will know where the most serious risks exist. ![]() Having an arc flash boundary at this level allows people to work in the area with the understanding that if they cross the line, the danger goes up significantly. Third-degree burns are much more serious, can leave extensive scarring, and cause long term disabilities. While nobody wants to get any type of burn, second-degree burns are very treatable. approach distances calculator for energized equipment makes it easy. This energy level is sufficient to cause second-degree burns, but not third degree.Ĭalculate your minimum approach distance (MADs) Arc flash boundaries are calculated to be the distance from the equipment until the point where the energy from the arc flash would be 1.2 cal/cm2. Many people mistake an arc flash boundary for being the distance from an electrical system that an arc flash, or its heat, can cause injury to a person. These boundaries will let employees and others in the area know where the most serious danger is so they can avoid it whenever possible. To help keep those who work around electrical equipment safe, facilities need to set arc flash boundaries. Of course, anyone who comes into contact with the arc flash will also experience electrocution, which can be deadly. Anyone in the area is going to be exposed to extremely high temperatures, which can cause serious burns very quickly. They are most dangerous, however, for those who are in the immediate vicinity of where the fault occurs. Arc flashes are dangerous events that can impact an entire facility. ![]()
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