What is IEE1584?
IEEE1584 is the industry accepted ‘Guide for Performing Arc-Flash Hazard Calculations’. 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.
What is NFPA70E?
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.
NFPA70E requires employees to wear flame resistant protective clothing wherever there is a risk of exposure to electric arc flash. 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.
What is AS4836?
AS4836 is an Australian Standard written for when electrical workers are working on or near live parts. AS/NZS 4836:2011, specifies Arc Flash PPE that must be used in certain situations. The Arc Flash PPE specified is of American Standards rating (NFPA 70E). 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). As one world expect, higher risk tasks require higher rating pieces of PPE.
What is an Arc Rating?
An 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. Arc rating is normally expressed in cal/cm2 (0.5 to 1 cal/cm2 = hottest part of lighter in 1 sec). An exposure of only 1-2 calories will cause second degree burns on human skin. Typical non-Flame Retardant workwear can ignite at energies as low as 2 calories.
The categories of PPE as described in NFPA 70E are as follows:
What is Arc Thermal Performance Value (ATPV)?
Arc 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. ATPV is a rating assigned to Flame Retardant Clothing indicating the level of protection provided. Higher fabric weights typically have higher ATPV’s and provide increased protection as does the layering of Flame Retardant Clothing. ATPV is measured in calories per centimeter squared (cal/cm2).
What is a Calorie?
A 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. Without protection, according to the Stoll Curve, it takes about 1.2 cal/cm2 to cause a second degree burn.
What is HRC?
Hazard Risk Category is a rating range directly related to ATPV. 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.