Understanding all of the acronyms for clothing and standards in the electric industry can make your head spin. One common question we get is: what is the difference between arc-rated and flame resistant clothing – if there is any difference at all?
FR stands for “flame resistant clothing,” specifically. An easy way to think about the difference between arc-rated clothing and FR clothing is that all arc-rated clothing is FR but not all FR has an arc rating. Confusing, we know. Let’s look at the two in more detail below.
One primary requirement for both arc-rated and FR clothing is to resist ignition, as tested by ASTM D6413, or the Vertical Flame Test. The second requirement for arc-rated clothing, specifically, is to insulate the wearer from arc flash hazards, thus reducing or eliminating any 2nd or 3rd degree burns through the garment. This is where a garment’s arc rating is important.
The term arc-rated was first introduced in the 2012 version of NFPA 70E. Informational Note No. 1 on page 12 of the standard explains, “Arc-rated clothing or equipment indicates that it has been tested for exposure to an electric arc. Flame-Resistant (FR) clothing without an arc rating has not been tested for exposure to an electric arc.” Due to the misuse of the term “FR,” NFPA 70E removed the term favoring arc-rated.
ASTM 1959 is the official arc rating test standard, and requires fabrics to be FR in order to even qualify for testing. The purpose of the ASTM 1959 test is to determine how much heat a certain fabric (or system of fabrics) will block from an electric arc before the onset of second degree burns to the wearer. This is the reason why all arc-rated clothing is FR.
OSHA 1910.269 Update: Arc-Rated vs. FR Clothing Requirements
One of the goals of OSHA, in its update, is to require protection from arc flash hazards – going beyond the legacy of 1910.269’s “do no additional harm” requirement.
FR Clothing: In the new standard 1910.269, OSHA does not define FR. However, OSHA does specify that clothing must be “non-melting.” OSHA prohibits the use of clothing made from acetate, nylon, polyester, rayon, and polypropylene, either alone or in blends, unless the employer demonstrates that the fabric has been treated to withstand the conditions that may be encountered by the employee or that the employee wears the clothing in such a manner as to eliminate the hazard involved (1).
As part of the revised OSHA standard becoming law on July 10th, there is a federally-enforceable requirement for FR clothing under the following conditions:
- The employee is exposed to contact with energized circuits parts operating at more than 600 volts;
- An electric arc could ignite flammable material in the work area that, in turn, could ignite the employee’s clothing;
- Molten metal or electric arcs from faulted conductors in the work area could ignite the employee’s clothing, or
- The incident heat energy estimate exceeds 2.0 cal/cm2 if a hazard analysis has been completed, or could reasonably be expected to exceed 2 cal/cm2 if a hazard analysis has not been completed (p. 390). (2)
Please Note: FR clothing, for use in instances outline above, does not currently have to be matched to the hazard, but must be provided by the employer at no cost to the employee. OSHA has issued a temporary delay on citations under the new rule until October 31, 2014. With this delay, workers need to be outfitted in “non-melting” FR clothing at minimum. The new ruling won’t be enforced by OSHA until the end of October.
There are several different methodologies that one could use to determine if an item is FR or not. The most common test in the United States is the Vertical Flame Test we previously mentioned. The European standard is a flame impingement test, which is a lower threshold of resistance to ignition. Some organizations cite 100% cotton denim’s natural resistance to ignition from electric arc as a type of flame resistance – assuming the hazard is electric arc (IEEE Paper No. PCIC-97-35 cites the ignition threshold of 12.8 oz. blue denim at 15.5 cal).
Under the third scenario, 100% cotton jeans may be considered acceptable as flame resistant since they are non-melting. However, depending on the weight, color and condition of cotton jeans, as well as the incident energy of the arc, 100% cotton jeans can ignite. Click here to watch Tyndale’s testing video showing results of FR and non-FR pants exposed to an electric arc. As the video shows, cotton fabric can and will ignite, and continue to burn if exposed to an ignition source. The non-FR jeans tested are made of 100% cotton, and continue to burn after the source of flame is removed (on the left), even though they do not “melt.” However, the FR jeans immediately self-extinguish (on the right). This video is a valuable demonstration of why it is important to protect both the upper and lower body with FR clothing.
Arc-Rated Clothing: OSHA is requiring employers to complete an arc flash assessment (previously called a hazard assessment) by January 1, 2015. Arc-rated clothing is required when employees are working on or near exposed live parts greater than 600V. Under such conditions, clothing could be ignited by:
- nearby flammable material that could be ignited; and/or
- molten metal splatter from electric arcs (1).
OSHA’s revised standard will be the first law with a national scope to require arc flash calculations (effective January 1, 2015) and electrical PPE to be arc-rated (flame resistant). Employer-provided arc-rated clothing matched to the hazard must be provided by April 1, 2015. This extended date for arc-rated clothing allows time for the industry to adapt from the old requirement of simply FR.
FRC Suppliers, like Tyndale, can help you stay compliant with OSHA’s updated ruling, and help you explain how their clothing can protect your employees, and against which hazards. All Tyndale-branded clothing meets both FR and arc-rated clothing requirements, as defined by OSHA. As a safety enhancement, Tyndale now includes an exterior label on all our manufactured garments that indicates both a garment’s arc rating and its hazard risk/PPE category rating. This means that your employees’ garment protective levels are visible at all times—and that you know it’s arc-rated.
For more information on Tyndale’s complete line of arc-rated and flame resistant clothing, please visit www.tyndaleusa.com. Not in a Tyndale-managed clothing program? Email email@example.com to learn more about Tyndale’s solution for OSHA’s updated standard.
References for this post were accessed June & July 2014: