arc flash boundary vs limited approach boundary

These boundaries move from least to most dangerous as follows: The NFPA has developed specific approach boundaries designed to protect employees while working on or near energized equipment. Further, a documented, management-approved plan, known as an energized electrical work permit, is required to enter a restricted space.

No unauthorized conductive material or unqualified people are permitted to cross a restricted boundary. This is the distance at which only qualified personnel are allowed, with appropriate protective clothing and other PPE for the associated hazard. Only qualified individuals and escorted unqualified people are allowed to enter a limited space. The second item is the limited approach, which is the distance at which barriers should be placed to protect unqualified personnel from an electrical hazard. People must not cross this boundary unless they are wearing appropriate protective clothing and are under the close supervision of a qualified individual. First is the flash protection boundary, the distance at which the incident energy from the live part is equal to 1.2 cal/cm2 (calories per square centimeter), which is the limit for a second-degree burn on bare skin. When determining what the arc flash boundaries are, the assessment includes three separate items. This risk assessment determines the various arc flash boundaries, as well as the PPE that must be used when approaching each boundary. The National Fire Protection Association’s NFPA 70E contains requirements for performing a shock and arc flash hazard assessment, which involves a calculation performed by a professional engineer to determine the incident energy found at each location. Three factors determine the severity of an arc flash injury:Īrc flash incidents can result in extreme heat exposure, burns, fires, flying objects and sound blasts.

The temperature of an arc flash can reach upwards of four times hotter than the sun! The results can cause serious injury and even death.

Arc Flash Protection: Information to Help Keep Workers SafeĪn arc flash is a phenomenon where a flashover of electric current leaves its intended path and travels through the air from one conductor to another, or to the ground.

Arc flash boundary vs limited approach boundary