What is an Arc Flash Hazard Risk Category?
Arc Flash hazard/risk category is specified as a number representing the level of danger, which depends upon the incident energy (the amount of energy impressed on a surface, a certain distance from the source, generated during an electrical arc event). The category ratings range from 0 to 4 where category 0 represents little or no risk, and category 4 signifies the greatest risk. Above category 4 (>40 calories/cm2) all equipment is considered too dangerous to work on energized because of the tremendous pressure blast. All parts of the body that may be exposed to the arc flash need to be covered by the appropriate type and quality of PPE.
This site is designed to provide you with the proper Personal Protective Equipment requirements, or PPE for each category.
What PPE Should I wear?
Selection of appropriate PPE, given a certain task to be performed, is normally handled in one of two possible ways. The first method is to consult a hazard category classification table, like that found in NFPA 70E. Table 130.7(C)(9)(a) lists a number of typical electrical tasks are various voltage levels and recommends the category of PPE that should be worn. For example when working on 600 V switchgear and performing a removal of bolted covers to expose bare, energized parts, the table recommends Category 3 Protective Clothing System. This Category 3 system corresponds to an ensemble of PPE that together offers protection up to 25 cal/cm2 (105 j/cm2 or 1.05 MJ/m2). The minimum rating of PPE necessary for any category is the maximum available energy for that category. For example, a Category 3 arc-flash hazard requires PPE rated for no less than 25 cal/cm2 (1.05 MJ/m2).
The second method of selecting PPE is to perform an arc flash hazard calculation to determine the available incident arc energy. IEEE 1584 provides a guide to perform these calculations given that the bolted fault current, duration of faults, and other general equipment information is known. Once the incident energy is calculated the appropriate ensemble of PPE that offers protection greater than the energy available can be selected. Reducing the frequency and severity of incidents should be the first option and this can be achieved through a complete arc flash hazard assessment.
ITU strives to provide the best protection for you and your employees. We have long been a provider of OEL personal protection equipment (PPE) and now OEL’s latest line of PPE called TecaSafe plus is the most advanced fire rated and arc flash PPE available on the market. Watch the video and see for yourself!
For more information about TecaSafe plus Click Here