![]() So why has it only received attention over the past 25 years? Only during the past few decades has the science caught up with our desire and need to protect our workers from these hazards. ARC-FLASH HAZARDS, SAFETY, AND ANALYSIS HISTORYĮlectrical arc-flash hazards have been a danger to workers since the early attempts to produce and harness electricity. Practical concepts will be offered for applying equipment variables and streamlining the process of adopting the new calculation methodology. We’ll wrap up the second part of this article by discussing the relevant impact of these changes and how they affect the calculated incident energy levels that we depend on to select adequate PPE. Part II ( NETA World Summer 2022) will compare the calculation results between the 20 methods. We will review key changes to IEEE 1584 from the initial edition in 2002 to the second edition in 2018 and examine the calculation process and variables included in the calculations. I refer to this as the Jurassic Period for electrical safety. It was during this period that OSHA was formed and NFPA began developing the 70E standard. Part I includes a brief history and evolution of electrical safety over the past 50 years. And in the end, will it make a difference?.How do you determine the needed information on the equipment?.While the changes improve calculation accuracy and can enhance safety, they do require a significant amount of equipment information to be gathered and used in the calculation process. ![]() Now, three years since its release, facility owners and arc-flash service providers still debate how, when, and where to apply the new calculation methods. 1584, IEEE Guide for Performing Arc-Flash Hazard Calculations. There are 5 HRCs ranging from 0 to 4, with a hazard risk of 0 presenting the least risk and a hazard risk of 4 being the greatest risk.In 2018, major changes were made to the calculations and procedures for determining arc-flash incident energy levels from the original 2002 edition of the IEEE Std. Hazard Risk Category is a rating range directly related to ATPV. Without protection, according to the Stoll Curve, it takes about 1.2 cal/cm2 to cause a second degree burn. ATPV is measured in calories per centimeter squared (cal/cm2).Ī Calorie is an energy measurement used to characterize the amount of arc flash energy which is required to cause a second degree (blister burn) on human skin. ![]() Higher fabric weights typically have higher ATPV’s and provide increased protection as does the layering of Flame Retardant Clothing. ATPV is a rating assigned to Flame Retardant Clothing indicating the level of protection provided. What is Arc Thermal Performance Value (ATPV)?Īrc Thermal Performance Value is the incident energy on a material that results in sufficient heat transfer through the material for a 50% probability of the onset of a second-degree burn on human tissue. The categories of PPE as described in NFPA 70E are as follows: Typical non-Flame Retardant workwear can ignite at energies as low as 2 calories. An exposure of only 1-2 calories will cause second degree burns on human skin. Arc rating is normally expressed in cal/cm2 (0.5 to 1 cal/cm2 = hottest part of lighter in 1 sec). As one world expect, higher risk tasks require higher rating pieces of PPE.Īn Arc Rating is the maximum incident energy resistance demonstrated by a material (or a layered system of materials) prior to break-open or at the onset of a second-degree skin burn. ![]() AS/NZS 4836:2011 specifies certain cal/cm2 (or simply ‘cal’) ratings certain pieces of PPE are now required to have for various tasks (when working on or near live parts). The Arc Flash PPE specified is of American Standards rating (NFPA 70E). AS/NZS 4836:2011, specifies Arc Flash PPE that must be used in certain situations. Although it is a voluntary standard, NFPA70E is considered a generally accepted industry standard in the USA, and even in Australia and New Zealand throughout general manufacturing as well as the electrical industries.ĪS4836 is an Australian Standard written for when electrical workers are working on or near live parts. NFPA70E requires employees to wear flame resistant protective clothing wherever there is a risk of exposure to electric arc flash. The National Fire Protection Agency’s (NFPA) 70E is the Standard for Electrical Safety Requirements for Employee Workplaces is the industry accepted standard in North America, Australia and New Zealand that helps decide how to protect workers based on the arc flash rating of equipment, as calculated form IEEE 1584. This guide provides mathematical models for designers and facility operators to apply in determining the arc-flash hazard distance and the incident energy to which workers could be exposed during their work on or near electrical equipment. IEEE1584 is the industry accepted ‘Guide for Performing Arc-Flash Hazard Calculations’.
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