If you work in an industry where you might encounter arc flash hazards, you’re probably required to wear arc-rated PPE for at least part of the time you’re on the job. Much as an outdoor weatherproof enclosure protects electrical devices in potentially hazardous locations, arc flash clothing protects workers who could be injured or killed by an arc flash from a high voltage device.
Arc flash protective clothing is an absolute must for many workers, but it can seem a little confusing and complex at first. If you’re new to protecting yourself with an arc flash kit, read up on the basics of arc flash protective gear here. We’ll talk about some of the most important components of an arc flash kit and how to start determining which ones you need.
What Is an Arc Flash Kit?
An arc flash kit refers to the PPE that protects workers who might be exposed to an arc flash. It’s composed of various pieces of arc-rated clothing, typically including at least a shirt, pants, and footwear. Other possible pieces of an arc flash kit include a jacket, coveralls, face shield, gloves, and hearing protection.
These clothes are designed to shield and insulate the wearer from the worst effects of arc flashes, including heat, shrapnel, and pressure waves. In addition, normal fabrics like cotton or nylon may ignite and/or melt when exposed to the heat of an arc flash. The clothing in an arc flash kit, by contrast, is made from non-flammable fabrics that absorb heat energy without catching fire, which helps protect workers from burns.
Why an Arc Flash Kit Is Necessary
With 30,000 arc flash incidents occurring in the United States every year, there’s a significant chance that anyone who works with industrial electrical systems will see this phenomenon at least once in their lifetime. Arc flashes produce incredible amounts of heat and energy that can easily kill or permanently disable you.
Even if you always make an effort to follow the right safety procedures against arc flashes, human error can cause all kinds of unforeseen circumstances. In addition, there’s no guarantee that someone who worked on a system before you was just as careful. Hidden dangers like dust building up inside an indoor electrical enclosure can cause an arc flash when you least expect it.
When the stakes are so high, the only sensible answer is to take precautions. That’s why many jobs that involve working with high voltage currents require workers to suit up in arc flash protective gear. OSHA and the NFPA 70E electrical safety standard require the use of an arc flash kit when performing activities (such as racking breakers) that have a high risk of arc flashes.
Components of an Arc Flash Kit
The required arc flash kit components will vary depending on the incident energies (see below) that you’ll be exposed to. At a minimum, you’ll probably need:
- Long pants and a long-sleeve shirt made from flame-resistant (FR) fabrics
- Leather footwear
- Hearing and eye protection
Other elements, like face shields and balaclavas, may be required for higher incident energies. Coveralls are also a popular choice for arc flash protection because the wearer doesn’t have to deal with separate garments or calculate the combined arc rating of multiple garments.
Finally, it’s also important to ensure that components like zippers and buttons are made from flame-resistant materials. Otherwise, they may catch fire, even if the garment itself doesn’t.
How Arc Flash Kits Are Rated
Rating arc flash protective clothing gets a little complicated, so let’s break down the key basic concepts here:
- Incident Energy: Put simply, this is how hot and severe you can expect an arc flash in a given work environment to be, depending on your distance from it. Calculating the incident energy through an arc flash study is key for determining the level of arc flash protection that you need.
- Calorie Rating: Arc ratings are expressed in calories per square centimeter (cal/cm2). This identifies the amount of heat energy that a square centimeter of the fabric can absorb. Calorie rating is the most important metric for determining arc performance, although it’s not the only one.
- Arc Thermal Performance Value (ATPV) and Energy Breakopen Threshold (EBT): These two terms are part of a complex calculation involving the point at which clothing allows second-degree burns and the point at which it breaks open from heat. Although arc clothing is usually listed either as ATPV or EBT, both are useful for different applications.
- Hazard Risk Category/CAT Level: The NFPA 70E standard establishes several different categories, formerly known as Hazard Risk Categories (HRCs) but now referred to as CAT levels. Each CAT level has a minimum calorie rating, giving workers and safety managers a useful shorthand for finding the right protective gear.
- Number of Washes: Arc protective clothing has a defined lifespan based on the number of wash cycles it can withstand before it no longer offers the right protection.
Where to Get an Arc Flash Kit
Your workplace is required by OSHA to purchase appropriate arc flash hazard PPE for anyone who could be exposed to an arc flash. If you’ve realized you don’t have the appropriate arc-rated PPE, raise the issue with your supervisor immediately before the next time you work in a situation that requires it.
Employers should purchase their arc flash kits from a specialty safety clothing company. These clothes aren’t available from most normal workwear retailers, and safety clothing companies know how to help employers find the exact arc-flash-rated clothing they need.
Understanding and working with arc flash PPE is a huge element of proper safety precautions in many types of electrical work. Take time to regularly review PPE standards for your job and make sure you’re in compliance because there’s simply no substitute for wearing the appropriate level of arc-rated clothing.
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