Best Dressed: Flame-Resistant Clothing

Much has been written about the dangers of electricity and the importance of following proper work practices. This includes the use of personal protective equipment (PPE), which is the last line of defense.
Clothing is somewhat of a different story. Initial regulatory language merely stated that clothing could not “increase the extent of injury that would be sustained by the employee.” As a result, most of the attention had been on whether or not it was to be classified as PPE. Employers and employees opposed the use of flame-resistant (FR) clothing. Since then, the industry has come to accept the need for it and is working on how to implement a FR clothing program. But to be effective, a program must not only ensure proper selection based on the hazard; it must also address cost and care of the garment as well as employee comfort.

Of course, selecting the proper clothing based on protection level comes first. A hazard analysis must be performed that includes a shock hazard analysis and an arc flash analysis. The arc flash analysis will determine an arc flash protection boundary (AFPB) and the heat energy exposure in calories per centimeter squared (cal/cm2) within that boundary. The AFPB is the distance from exposed energized conductors and parts in which a worker could receive a second-degree burn if an arc flash occurs. Second-degree burns can occur at energy levels of 1.2 cal/cm2. The clothing worn inside the AFPB must prevent second-degree burns.

The National Fire Protection Association (NFPA) 70E, the Standard for Electrical Safety in the Workplace, has identified various hazard risk levels associated with a given arc flash’s energy as seen in the table on page 60. The table also identifies the minimum arc thermal protection value (ATPV) of the clothing needed at that risk level. The question then becomes how to determine the incident energy level of the potential arc that may occur during a given task.

One method of determining the incident energy level is to perform a detailed engineering calculation. At least three methods are available, including two methods offered by the Institute of Electrical and Electronics Engineers (IEEE) 1584, “Guide for Performing Arc-flash Hazard Calculations,” and one from NFPA 70E.

Software calculators also are available for these methods on equipment manufacturers’ Web sites. Each of these formulas will yield different results for a given task. No one calculation format can be used for all circuit conditions. Some manufacturers even offer equipment-specific calculators.

Whichever calculation method is used, the actual conditions must be within the ranges applicable for that method; variables, such as working distance and bus gap, must be accurately assessed; and realistic fault current values used. Whenever possible, device-specific equations should be used.

An easier method for determining incident energy level (i.e., hazard risk category) is to use the simplified tables. NFPA 70E Table 130.7(C)(9) links tasks to hazard risk categories, and Table 130.7(C)(10) is the Protective Clothing and Personal Protective Equipment (PPE) Matrix. The National Electrical Contractors Association (NECA) has developed the NFPA 70E Personal Protective Equipment (PPE) Selector Manual (Index No. 5024R) and NFPA Personal Protective Equipment Selector (PPE) CD (Index 5024CD) to streamline selection. The manual allows users to flip to the PPE needed for a given task. The software CD offers interactive selection of equipment and training including a PowerPoint file. The only limitation to the table method is that guidance is specific to the task and conditions listed. Calculations must be performed for tasks that do not fit these specifications.

Regardless of the method used, once the hazard risk category is determined, NFPA 70E Table 130.7(C)(10) is the key to choosing the clothing needed. For Hazard/Risk Category 0, the table shows that only nonmelting or natural fabric, such as cotton, is needed. As the hazard risk category increases, the level of protection increases. With a hazard risk category of 1, the clothing selected must have an ATPV of at least 4 cal/cm2, and with Hazard Risk Category 2, the minimum ATPV is 8 cal/cm2. The maximum hazard risk category at which work can be performed within the AFPB is 4. Work is not permitted when the energy level is above 40 cal/cm2. The NFPA 70E tables should be consulted for options on achieving the overall protection levels as well as the other PPE needed.

There are a wide variety of clothing options for meeting the ATPV for a hazard risk category. For starters, the fabric must be considered. Cotton or cotton-blend fabrics can be made flame-resistant by application of a flame retardant. Other fabrics, such as Nomex, are inherently flame-resistant. Both inherent and treated FR fabrics offer protection. Each has its own benefits and drawbacks, and based on these properties, one will serve a better purpose than another for the conditions. The following is a breakdown of the benefits of some of the fabrics.

• Modacrylic fabric is soft and resilient. If you need brighter shades, this is a good fabric. It accepts dyes readily. It also resists abrasions and damage from acids and alkalis. It dries quickly and will keep its shape.
• Lyocell or cellulosic is as soft as silk. It is also a strong fabric. It will accommodate workers that are exposed to variable temperatures. It performs like linen in warmer temperatures, keeping the worker cool, yet it acts like wool in colder temperatures.
• Rayon or viscose is also a soft fabric. It is smooth, cool, comfortable, highly absorbent and color friendly, and it has good breathability.
• Treated nylon is often used in small percentages with other fabrics in clothing to enhance durability and resistance to surface abrasion.

Another consideration is the cost. Do not be misled by the sticker price of the garment. Treated cotton, for example, may have a lower cost, but the life of the garment may be shorter. The FR treatment of that type of garment can wash out as opposed to an inherently FR fabric garment.

Carefully weigh your options. In addition to the impact of care on the garment, the manner in which it will be used will affect its life. Garments should be replaced when they have holes or tears that cannot be repaired or when the fabric has thinned or become threadbare, is contaminated or visually unappealing. Some garments can last more than 5 years, while others only 9 to 18 months. Since there is no way to determine when the FR has worn off, only garments for which the manufacturer guarantees the protection lasts for the life of the garment should be used.

As mentioned, care of the garment can have a serious impact on the life of the garment. Each garment is different. The manufacturer’s instructions for laundering are on the label of every garment and must be followed. The following general instructions apply to most. Employees may launder their own clothing at home. FR garments should be washed separately in warm water with a maximum setting of 140°F. They can be dried using the permanent press cycle at a temperature of 160°F. Detergents that are normally used for other garments are acceptable. Liquid fabric softeners put in the wash with the fabric should not be used. This can leave a flammable residue on the fabric. Different recommendations are given by manufacturers with regard to fabric softeners used in the dryer. One may allow it, while another prohibits it. This may be dependent on the fabric and/or treatment used in the garment. Chlorine bleach is not recommended by any manufacturer. It should not be used.

Table 1 from NFPA 70E: Levels of Exposure
Calculated Incident Energy Hazard Risk Category Minimum ATPV Rating
Up to 1.2 Cal/cm2 Category (NA)
1.2 to 4 Cal/cm2 Category 1 4
4.1 to 8 Cal/cm2 Category 2 8
8.1 to 25 Cal/cm2 Category 3 25
25.1 to 40 Cal/cm2 Category 4 40
Over 40 Cal/cm2 No Category—Not Permitted No Category—Not Permitted

Many FR garments can be industrially laundered. Before dismissing this as costly, the supplier or manufacturer should be consulted. Depending on the fabric and the willingness of employees to adhere to specific laundering guidelines, industrial laundering may offer a savings. It can ensure proper care of the garment, thereby extending its life.

The cost consideration for laundering or any other factor discussed thus far has been without regard for who is making the payment, but done so as though it was one source. This does not mean employers are required to pay. OSHA made clear in the preamble to the new Employer Payment for Personal Protective Equipment Final Rule that this equipment would only be covered in those instances where it is required by OSHA standards. If provided because of NFPA 70E, it should be understood this is a consensus standard. Although OSHA may refer to it as an example of proper protection to substantiate a General Duty citation, it is not an OSHA standard. Therefore, employer payment is not required.

Regardless of who actually pays for the clothing, it may be best for the employer to negotiate with a supplier or manufacturer. Doing so offers the control over the factors previously mentioned. It can also provide other opportunities, such as setting up a free wear trial to test garments and build employee buy-in or special pricing for uniform placement of embroidery/emblems. Employer purchasing can also allow alternate programs for supplying FR clothing (e.g., a uniform rental agreement with a laundry company). And again, this does not preclude employee payment. A payroll deduction program can be set up to accommodate costs.

A FR garment program can be complex. This article has touched on some of the highlights for implementing an effective program. But, there is much to be considered, and the questions can seem endless. Sizing, undergarments and outer garments are just a few additional factors. As identified here, the supplier or manufacturer plays a key role. Their support is critical. In its absence, there are consultants who can offer guidance. The protection afforded by FR clothing is too great to manage without a good understanding of all that needs to be considered.

O’CONNOR is with Intec, a safety consulting, training and publishing firm that offers on-site assistance and produces manuals, training videos and software for contractors. Based in Waverly, Pa., he can be reached at 607.624.7159 and

About the Author

Joe O'Connor

Freelance Writer

Joe O'Connor is with Intec, a safety consulting, training and publishing firm that offers on-site assistance and produces manuals, training videos and software for contractors. Based in Waverly, Pa., he can be reached at 607.624.7159 or joconnor...

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