For those working around electrical equipment, the risk of an arc flash poses a significant health and safety risk.
An arc flash refers to the flash of light and heat generated when energy is released between a live conductor and the ground or another conductor. Like a lightning bolt, this explosion releases intense energy through heat, light, and a pressure wave. The energy released during an arc flash heats the air to extreme temperatures, reaching 35,000 °F (three times the sun’s temperature). Anything within 3 feet, such as clothing and skin, will ignite, melt, or vaporize at that temperature.
Flame-resistant clothing helps to prevent severe injury due to an arc flash. It protects against extreme temperatures and flame, reducing the risk of second or first-degree burns. Wearing flame-resistant clothing saves lives and prevents injuries that require significant recovery time.
Continue reading as we examine arc flash clothing requirements, what contributes to an arc flash, what is arc flash protection, and the types of protective clothing that can be worn on the job.
What Causes an Arc Flash?
An arc flash can cause significant harm, so it’s vital to understand the potential causes of the electrical event. The triggering factors are often related to conditions or actions that allow electricity to jump through the air from one conductor to another or the ground. These factors can include:
- Equipment failure. Faulty or aging equipment can often lead to an arc flash. This could be due to various issues, including insulation failure, dust build-up, corrosion, or wear and tear.
- Accidental contact. An arc flash can occur when a conductive tool or another object inadvertently comes into contact with electrical parts. This might happen during maintenance or repair when a tool slips or someone accidentally touches an electrified component.
- Incorrect installation. If electrical systems or components are incorrectly installed, it can create conditions where an arc flash can occur. This includes improper assembly, loose connections, or misalignment of parts, among other installation issues.
- User error. Operating electrical equipment outside specified limits or not following recommended procedures can trigger an arc flash. This might involve overloading circuits, bypassing safety devices, or neglecting to de-energize equipment during work.
- Environmental factors. External factors like moisture, dust, or rodents can contribute to an arc flash. These elements can become conductive paths for electricity, contributing to an electrical discharge.
Arc Flash PPE Categories
Personal protective equipment (PPE) is pivotal in avoiding injury due to arc flash hazards. It serves as the last line of defense, protecting workers from suffering severe burns in the event of an arc flash.
The National Fire Protection Association’s (NFPA) 70E Standard for Electrical Safety in the Workplace outlines four categories of PPE for workers at risk of an arc flash. Each category corresponds to a specific range of incident energy (expressed in calories per cm²), which is the energy produced by the arc flash.
- Category 1 provides protection for arc flashes producing incident energy up to 4 cal/cm². PPE for this category usually includes flame-resistant (FR) shirts, pants, or FR coveralls, along with arc-rated face shields or goggles.
- Category 2 covers protection for energy levels up to 8 cal/cm². Along with the PPE included in Category 1, this may require an arc-rated flash suit, including a hood and gloves.
- Category 3 relates to arc flashes producing energy up to 25 cal/cm². This level requires wearing a complete arc-rated flash suit and the PPE listed in Categories 1 and 2.
- Category 4 is designed for the most dangerous levels of incident energy, up to 40 cal/cm². Full arc flash suits, including a hood and gloves, are required, often with additional protective FR-rated elements like balaclavas, belts, and underwear.
Arc Flash Clothing Requirements
Arc flash clothing is designed to resist ignition and prevent burning or melting when exposed to an arc’s intense heat. The material used in FR clothing must be non-conductive and not easily melted or ignited. This typically includes:
- Flame-resistant (FR) materials. These fabrics are chemically treated to be slow-burning and self-extinguishing. They’re designed to provide a barrier between the wearer and the heat of an arc flash, minimizing burn injuries.
- Arc-rated materials. These are a subtype of FR fabrics but with a specific rating for protection against electrical arcs. The rating, measured in calories per cm², indicates the material’s resistance to the heat energy from an arc flash that would cause a second-degree burn.
- Naturally flame-resistant materials. Unlike FR materials that are treated, these materials are naturally flame-resistant. They provide reliable protection since their flame resistance doesn’t wash out or wear away. Leather, kevlar, and some 100% cotton materials are examples of this type of material.
NFPA 70E FR Clothing Requirements
The NFPA 70E standard provides specific guidelines for arc flash clothing. According to NFPA 70E, workers must wear flame-resistant clothing whenever there’s a possible exposure to an electric arc flash above the threshold incident energy level for a second-degree burn (1.2 cal/cm²).
The clothing must cover potentially exposed areas and be layered to enhance protection. As mentioned earlier, the standard also classifies FR clothing into four PPE categories, each based on the specific incident energy levels in the working environment.
OSHA Arc Flash Clothing Requirements
In addition to NFPA 70E, companies must follow the requirements set forth by the Occupational Safety and Health Administration (OSHA). OSHA Standard 29 CFR 1910.269 states that employers are responsible for assessing the workplace for arc flash hazards, estimating the incident energy of any potential arc flash, and ensuring employees wear flame-resistant clothing that meets the estimated energy level.
Notably, OSHA also states that undergarments should be non-melting and that workers should avoid wearing clothing that could potentially increase the extent of injury, such as apparel made of synthetic materials like nylon or polyester, unless it’s flame-resistant.
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Don’t take chances with arc flashes. Get the gear you need by visiting BareBones WorkWear® today.