Choosing the right arc-rated FR garments to protect your workers.
There’s a lot of confusion around flame resistant (FR) arc-rated garments, from the standards to the ratings. But when employers are looking to protect their workers from job-related hazards, it’s essential to find the right garment.
Arc flash hazard is a dangerous condition associated with the possible release of energy caused by an electric arc. An arc flash gives off thermal radiation (heat) and bright, intense light. Temperatures have been recorded as high as 35,000 F, according to the National Institute for Occupational Safety and Health (NIOSH) in the United States.
The end result is a possible explosive event including flying shrapnel, hot molten metal and toxic smoke, says Len Cicero, president of Lenco Training & Technical Services in Burlington, Ont., and an executive member of the CSA Z462 technical committee (Canada’s first national workplace electrical safety standard).
An arc flash can be spontaneous or result from inadvertently bridging electrical contacts with a conducting object. Other causes may include dropped tools or the buildup of conductive dust or corrosion, according to NIOSH. An arc flash can occur while working on an energized circuit or through electrical equipment failure.
Arc flashes typically result in maiming injuries, such as severe body burns that require years of skin grafts and rehabilitation, so finding the right protective gear is critically important.
Arc-rated FR garments
Arc-rated fabrics are tested to see if the material itself is self-extinguishing and doesn’t continue to burn or melt after being exposed to a flame. ?Testing requires exposure to an electrical arc flash. The test looks at the amount of heat that’s transferred through ?the material.
For this type of risk, an employer should be looking for a garment that contains an arc rating, reported as either an arc thermal performance value (ATPV) or energy of break-open threshold (EBT). This is measured in calories per square centimetre (cal/cm²). About one calorie is equivalent to holding a cigarette lighter one inch under your finger for one second, ?says Cicero.
The minimum arc-rating depends on the hazard, as determined by a risk/hazard assessment.
The preferred method of performing an arc flash hazard assessment is to complete an incident energy analysis, according to Jim Pollard, subject matter expert for arc-rated PPE with Unlimited PPE in Stoney Creek, Ont. He is also a member of several technical committees related to workplace electrical safety, including CSA Z462.
This method requires engineering calculations that determine the incident energy (potential thermal energy created by an electric arc) exposure level based on the working distance for the task to be performed. Once these calculations are complete, employers can select arc-rated FR garments and personal protective equipment (PPE) based on the incident energy provided in cal/cm². Selection criteria requires the arc-rating of the PPE to be the same or higher than the incident energy exposure value.
In lieu of completing an incident energy analysis employers can use hazard risk category (HRC) levels, from zero to four, with four being the highest. An HRC level prescribes the minimum arc rating in cal/cm² needed to protect against a particular job-related hazard (the higher the number of calories or hazard risk category the greater the level of protection required).
If an employer were to refer to the task tables (Tables 4A or 4B) in the CSA Z462 standard and discover that the task was HRC level 4, the subsequent table (Table 5) would provide details on the required PPE for that task (for HRC level 4, the minimum protection required is 40 cal/cm²).
There are garment systems on the market that provide up to 140 cal/cm².
Because the CSA standards explain how to select proper PPE but don’t deal with performance requirements, design requirements or labelling of arc-rated textiles or garments, the CSA Z462 standard refers to standards from the American Society for Testing Materials (ASTM).
The ASTM F1506-10a standard provides a consistent rating system for arc-rated garments across North America. It is a performance specification “for flame resistant and arc-rated textile materials for wearing apparel for use by electrical workers exposed to momentary electric arc and related thermal hazards.”
In North America, most arc-rated FR textiles are tested at the Kinectrics Laboratory in Toronto, which provides testing documentation for single-layer and multi-layer fabric systems.
But this standard relates to the textile, not the garment, which means the garment itself may not meet the same standard for closures, stitching, seams and zippers, says Pollard.
Another standard, ASTM F2621-12, determines the response characteristics and design integrity of arc-rated garments in an electric arc exposure. This is used to evaluate finished products, such as shirts, pants or coveralls — ensuring there are proper closures, stitching, seams and zippers.
But since it’s hard to find documentation on this, it’s up to the employer to ask manufacturers for this information, says Pollard. (It’s not listed in CSA Z462-12 or NFPA 70E-12, the Standard for Electrical Safety in the Workplace developed by the National Fire Protection Association in the United States).
“This standard has not been referenced in best practice standards, so unless the employer knows about ?it they’re not going to ask about it,” he says.
And there is a separate standard, ASTM F2178-08, for eye or face protective products, and testing is done on both the arc flash suit hoods and face shields.
Electrical safety management
Employers should have an electrical safety program in place, says Cicero. The program should be integrated into an overall occupational health and safety management program.
An electrical safety program would help employers understand their risks, what type of PPE is appropriate and what training should be provided ?to workers. Ultimately, electrical ?equipment should be safe if it’s installed correctly and is in normal operating condition, but workers need to know how to do a field-level ?risk assessment.
“The workers themselves need to be engaged, need to be part of that decision-making process,” says Cicero, adding that most workers don’t understand the labels, proper laundering or proper maintenance of their ?PPE clothing.
“I’ve conducted over 500 audits ?of sites,” says Pollard. “The majority have PPE that’s brand new and never been used.”
It’s one thing to buy the right PPE; it’s another to show workers how to use it and maintain it, he says.
Making the purchase
Scott Margolin, international technical director at Chicago-based Westex, recommends employers look at information beyond arc ratings. They should look at whether the garment passes the test, but also at which number it passes the test. And look at whether a product or brand has a proven history and whether the manufacturer backs it if there’s a problem.
“Compliance is not enough,” says Margolin. “The compliance standards are the minimum bar required to get in the game.”
The arc-rating test is self-submitted and is rarely ever checked again, years later. The test is done under perfect laundering conditions and doesn’t give employers a sense of the durability of the FR properties over years of wear-and-tear under less-than-perfect laundering conditions, as well as shrinkage, abrasion and other issues.
“It’s a buyer-beware market,” says Margolin. “The ratings are a starting point — then you’ve got to do your homework beyond that.”
Vawn Himmelsbach is a Toronto-based freelance writer.
For more information, watch COS Magazine's recent arc flash safety video (embedded below) or in our video library here: