Understanding the Basics of Arc Rated Clothing: A Comprehensive Guide to Arc Flash Apparel

Arc flash apparel suits, specifically designed to protect against the hazards of arc flash incidents, were first introduced in the late 1980s. According to Industrial Safety & Hygiene News, “Most were made from double-layer 6 oz/yd2 NOMEX® and used polycarbonate (plastic) windows.” Arc testing of clothing and PPE began in 1996. Since then, arc rated clothing and personal protective equipment (PPE) has evolved to provide more effective protection against electrical arc flash incidents. The introduction of more robust standards for electrical safety and arc flash prevention by organizations like the National Fire Protection Association (NFPA) has led PPE manufacturers to design better performing arc-rated clothing and PPE. Today’s arc rated clothing allows for greater protection, comfort, and mobility thanks to the development of advanced FR fabrics and innovative design features.

Because arc rated clothing is so essential for arc flash and electrical safety compliance, it needs to be carefully selected, safely stored, and properly maintained. This guide explains the fundamental basics of arc rated clothing – what it is and how to select it – for employers and employees, including:

If you are completely new to the concept of arc flash hazards and PPE, we suggest first checking out our article on The Importance of PPE in Protecting Against Arc Flash Hazards. Otherwise, keep reading to learn how to select and use arc rated clothing & PPE.

What is Arc Rated Clothing?

Arc rated clothing is flame resistant (FR) clothing (such as shirts, pants, and coveralls) designed to protect wearers from arc flash burn injuries. Arc rated clothing is made from flame resistant fabric that is tested for its ability to protect against the thermal hazards associated with arc flash incidents. Arc rated clothing is carefully designed to resist ignition and prevent burning or melting during an arc flash incident. According to National Safety Apparel, “Arc rated gear won’t ignite, melt or drip and won’t contribute to additional injuries caused by the arc blast.”

Arc rated clothing also insulates the wearer from arc flash incident energy to prevent second-degree burns. Arc rated clothing, along with other PPE needed for arc flash injury prevention (such as arc-rated face shields and hoods), must be worn by employees performing work on energized systems.

Arc rated clothing (also known as arc flash clothing) is designed to be durable, protective, comfortable (without restricting mobility), and easy to remove.

Arc rated clothing generally refers to arc flash suits (which cover most of the worker’s body), shirts, pants, jackets, coveralls, and other garments made from arc-rated flame-resistant fabrics. Arc rated clothing can be made out of inherently FR fabric, treated FR fabric, or treated inherently FR fabric.

Other PPE (such as hard hats; ear canal inserts; insulated voltage-rated gloves with protectors; and leather boots) is required to provide head-to-toe protection from arc burns and other hazards associated with arc flash events.

How is Arc Flash Clothing Rated?

According to Safety+Health magazine, “Arc rating is defined as the amount of energy a given fabric can withstand before a 50 percent likelihood of the onset of second-degree burn through the fabric.” Arc rating essentially measures a FR fabric’s ability to insulate the wearer from second-degree burn through the fabric. ASTM F1959 (Standard Test Method for Determining the Arc Rating of Materials for Clothing) is the standard test method used to calculate the arc rating of single or multilayer systems of FR layers. 

Arc rating is expressed in cal/cm² (which means small calories of heat energy per square centimeter) and is derived from the determined value of the arc thermal performance value (ATPV) or energy of break open threshold (EBT). Arc rating is reported as either ATPV or EBT, whichever is the lower value.

ASTM F1506 (Standard Performance Specification for Flame Resistant and Electric Arc Rated Protective Clothing Worn by Workers Exposed to Flames and Electric Arcs) requires arc rated clothing to be properly labeled with its arc rating. Arc rating indicates the level of protection provided by FR clothing (specifically how much arc flash incident energy a garment can withstand), as measured in cal/cm² (calories per square centimeter). Higher arc flash hazards require clothing and protective gear with a higher arc rating.

What’s the Difference Between Arc Rated Clothing & FR Clothing?

Arc rated clothes are made out of arc-rated/FR fabrics like Westex UltraSoft, DRIFIRE, and Nomex. However, not all FR clothing is rated for arc flash protection. While regular FR fabrics may provide some level of flame resistance, they are not always designed to withstand the specific conditions and hazards associated with an arc flash. The extreme heat and energy from an arc flash event can cause severe skin burns, even if the clothing worn by an employee does not catch fire!

Arc rated clothing is designed to resist ignition and prevent burning or melting when exposed to the extreme heat of an arc flash. Arc rated clothing also acts as a barrier between skin and the intense heat generated by arc flash.

However, it’s important to wear AR/FR (arc-rated FR) clothing rated for the incident energy level of the potential hazard. The appropriate AR/FR clothing you select should have an arc rating equal to or exceeding the anticipated hazard level.

Common Types of Arc Rated Clothing & PPE

Before selecting arc rated clothing that’s appropriate for a specific work task, you’ll need to understand the various types of arc rated clothing and protective gear available. Head-to-toe protection is needed to protect electrical workers from arc burns and other arc flash injuries.

Arc-Rated Shirts, Pants, & Coveralls

A long-sleeve arc-rated shirt and pants can be worn to protect your torso, arms, and legs from arc burns and molten metal splatter. Alternatively, arc-rated coveralls can be worn (often underneath an arc-rated jacket). Skin should not be left exposed, so make sure your shirt is tucked into your pants, all buttons are buttoned, etc.

Any non-arc rated materials worn underneath your arc-rated clothing should be completely covered as well. Base layers or underwear should be constructed out of non-melting natural fibers like cotton instead of synthetic fabric. Conductive articles of jewelry and clothing, including cloth with conductive thread and garments with metal-based components such as metal closures, should never be worn within an arc flash boundary!

Arc-Rated Jackets & Vests

Jackets made from arc-rated materials, including arc-rated rain jackets, provide additional protection for the upper body in cold or adverse weather conditions.

Safety vests made from arc-rated materials enhance visibility and protect workers from the thermal hazards of arc flash incidents at the same time. They are often worn by roadside construction workers, utility workers, railroad workers, and workers in the oil and gas industry.

Hard Hat w/Arc Flash Hood or Face Shield

The extreme energy of an arc flash event can cause serious skin burns and eye damage. You will need to wear either an arc-rated hood or face shield with “wrap around” guarding (i.e arc-rated balaclava). According to NFPA 70E 2021, you must choose an arc flash suit hood for exposures greater than 12 cal/cm².

You should also wear a Class E hard hat (with arc-rated hard hat liner) underneath an arc flash hood or as part of a hard hat/face shield combination. Class E hard hats provide protection against electrical shock and flying debris.

Safety Glasses

You must also wear safety glasses or safety googles under an arc flash hood or arc flash face shield to further protect your eyes from arc flash and arc blast hazards.

Ear Plugs

Arc flash noise can cause temporary or permanent hearing damage. NFPA 70E requires ear canal inserts (ear plugs) to be worn in all arc flash zones.

Voltage-Rated Gloves w/ Leather Protectors

Voltage-rated rubber insulating gloves with heavy-duty leather protectors are typically worn to protect against electrical shock and arc flash.

Leather Boots

Heavy-duty leather footwear or dielectric footwear provide some arc flash protection to the feet and should be worn if the arc flash incident energy exposure is greater than 4 cal/cm². Dielectric steel toe leather boots are often worn as part of an arc flash PPE ensemble.

Arc Flash Rated Fall Protection

Linemen and utility workers who perform tasks on utility poles, electrical towers, or other elevated structures may require arc-rated fall protection equipment, including safety harnesses.

Arc rated clothing and other PPE is often sold in bundles known as arc flash suits or arc flash kits. Arc flash kits include arc rated clothing and other PPE needed to provide full body protection, stored in a convenient easy-to-grab bag.

How to Select Arc Rated Clothing

An arc flash risk assessment or arc flash study should always be conducted prior to energized work to help determine what level of PPE is needed to keep workers safe from arc flash hazards. An arc flash study determines the incident energy level associated with potential arc flash hazards in an electrical system. Incident energy level is typically expressed in cal/cm². This information guides the selection of arc rated clothing with an arc rating that equals or exceeds the identified hazard.

A thorough arc flash study uses safety guidelines like NFPA 70E (Standard for Electrical Safety in the Workplace) and IEEE 1584 (IEEE Guide for Performing Arc-Flash Hazard Calculations) to determine PPE requirements (i.e. what type of PPE must be worn by qualified employees performing work on energized equipment to prevent arc flash injuries).

There are two methods that can be used for the selection of arc flash PPE: incident energy analysis or the arc flash category method. NFPA 70E requires arc flash warning labels to be affixed to each piece of electrical equipment likely to require access while energized. Arc flash labels for equipment will display the information needed to select arc rated clothing and other protective gear. A label may include the available incident energy and corresponding working distance OR the arc flash PPE category (but not both). Alternatively, a minimum arc rating of clothing or site-specific PPE designation can be listed on a label.

In order to select appropriate arc rated clothing and PPE for a work task you’ll need to:

  • Learn how to read arc flash warning labels – this is absolutely key to selecting the appropriate arc rated clothing and PPE that’s right for your task. For more information, check out this in-depth guide to Understanding Arc Flash PPE from Electrical Safety in the Workplace magazine.
  • Remember to check the label of your arc rated clothing to find its ATPV or EBT rating (listed in cal/cm²) – this rating means the garment will protect the wearer from arc flash energies up to that value. If the possible incident energy exceeds the arc rating of a garment, the wearer needs to select clothing with a higher arc rating. Layering multiple garments can also help achieve the required level of protection.
  • Always consult with your supervisor or safety manager – to learn more about how to select the right arc rated clothing and PPE for your work environment and energized electrical work tasks. Many employers have site-specific PPE requirements. You’ll also need to make sure that the arc flash PPE you select protects against other hazards you may encounter such as electrical shock and flash fire.

Arc Flash PPE Categories

The arc flash category method is one method that can be used for the selection of arc rated clothing and other PPE meant to protect workers from the hazards of arc flash.

The concept of Arc Flash PPE categories was first introduced in the 2000 edition of NFPA 70E and has since been revised in subsequent editions. Electrical equipment labeled with a PPE category provides specifics on what arc rated clothing and other PPE a worker should wear to avoid arc burn injuries.

Table 130.7(C)(15)(c) of NFPA 70E ranks PPE by four category (CAT) levels. Each of these levels comes with specific PPE requirements for arc flash safety.

  • CAT 1 requires PPE with a minimum arc rating of 4 cal/cm²
  • CAT 2 requires PPE with a minimum arc rating of 8 cal/cm²
  • CAT 3 requires PPE with a minimum arc rating of 25 cal/cm²
  • CAT 4 requires PPE with a minimum arc rating of 40 cal/cm²

Most businesses purchase CAT 2 and CAT 4 PPE kits or arc flash suits. To learn what type of arc rated clothing and PPE is required for each category, check out this guide from Enespro.

How to Store & Maintain Arc Flash Apparel

To avoid reducing its protective value, arc rated apparel must be properly cared for, handled, and stored. Dirt, oils, and chemicals can reduce the effectiveness of arc flash clothing and PPE. Workers should be trained on how to maintain and disinfect arc rated clothing. Workers also need to learn how to inspect PPE for small tears, rips, and holes that compromise the protectiveness of AR/FR garments.

Check the label of your arc rated clothing for laundering instructions. Store arc flash apparel and PPE in a clean, dry, well-ventilated area that’s protected from sunlight, moisture, and pests. To learn more on how to care for and store AR/FR clothing and PPE, check out Enespro’s guide to Arc Flash PPE Maintenance.

Arc Rated Clothing: Frequently Asked Questions

What is an arc flash suit?

An arc flash suit is a set of arc rated clothing and PPE meant to provide full body protection from the thermal hazards of arc flash. Full arc flash suits typically include a jacket and bib overalls, arc flash hood or face shield, and voltage rated gloves.

Can you layer arc rated clothing?

Yes, layering arc rated clothing is a common practice that can be used to achieve a higher level of arc flash protection. To learn how to properly layer arc rated clothing, check out this article on Arc Flash Layering for Comfort & Compliance.

How do I know if my clothes are arc rated?

PPE manufacturers add labels or tags to their arc rated clothing that make it easy for the wearer to clearly recognize the upper limit of arc flash protection for that garment. These labels clearly indicate the official arc rating of the garment (listed in cal/cm²) such as 12 cal/cm² or 40 cal/cm².

Can you wash arc flash clothing?

Yes, arc flash rated clothing can be washed though you should only use mild detergent and avoid using fabric softeners. Check the label of your arc rated clothing for laundering instructions.

How often should arc flash clothing be replaced?

Most safety professionals agree that arc flash clothing should be replaced every five years or sooner. You may need to replace your arc flash clothing sooner if it is frequently worn/washed or becomes torn or soiled in a way that can’t be repaired. Arc-rated face shields and AR/FR hard hat liners should be replaced according to the manufacturer’s recommendations.

What clothing should be worn under arc flash PPE?

Undergarments worn beneath arc rated clothing should always be made from natural fibers such as 100% cotton, as cotton won’t melt when exposed to high heat.

Can arc flash clothing be customized?

Yes, arc flash clothing can be customized with logos or name tags. ASTM F1506 contains recommendations for customizing arc rated clothing with heat-transfer emblems and patches. We recommend using FR thread and FR patches on custom AR/FR garments. To learn more about customizing PPE, check out our guide to Branded PPE.

Stay Safe & Compliant with Highly Protective Arc Rated Clothing & PPE

OSHA requires employers to protect their employees from known hazards (General Duty Clause), including the extreme thermal heat and other hazards associated with arc flash. In the past, OSHA has used the General Duty clause to fine employers for failure to provide arc rated clothing and other PPE to employees at risk of arc flash incidents. In addition, OSHA 1910.269 mandates the use of appropriate PPE, including arc rated clothing, to safeguard workers in the electric power generation, transmission, and distribution industry from arc flash hazards.

Workers at risk of arc flash incidents need high quality and highly protective arc rated clothing and PPE. This keeps them safe and helps ensure compliance with OSHA regulations.

Ready to purchase lightweight, durable, and comfortable Enespro AR/FR clothing and PPE? Check out our collection of Arc Rated Clothing/PPE. Or fill out the form below to speak to a safety specialist about your arc flash apparel and PPE requirements today!