Seeing is believing with arc flash safety
February 20, 2007
I have been working with electrical power systems at a multinational Fortune 500 consumer goods manufacturing company for more than 40 years, and have the responsibility of establishing an NFPA 70E Electrical Safety Program at our sites worldwide. Of course, driving culture change is a difficult proposition, especially if the workforce or management doesn’t fully understand electrical hazards and the safeguards that are needed. The NFPA 70E Standard has heightened awareness of the hazard, but much more work needs to be done to educate safety professionals, engineers and the employees that work on or near energized parts and equipment; and one of the key areas is clothing.
Most of the severe and fatal burn injuries caused by arcs do not result from the arc itself, but from the victim’s flammable clothing igniting and continuing to burn long after the flash event is over. Clothing ignition causes more severe burns to occur over a larger body surface area.
It was widely understood in our facilities that clothing made from non-flame resistant synthetic fabrics that could melt is not appropriate when working on or near electrically energized parts and equipment. If these garments are exposed to an electric arc flash they can ignite, melt and drip, which leads to severe burns. But many people consider non-flame resistant 100-percent cotton fabrics to be “safer” in an electric arc flash, which is a very dangerous misperception.
Graphic demonstrationI have had the opportunity to participate in several innovative Electrical Safety/ NFPA 70E seminars that illustrated this point in the most graphic manner imaginable. Westex, Inc. hosted the events, which were held at the independent labs of KEMA Powertest in Pennsylvania. With the help of Mike Wright from 70E Solutions, they custom built a one of a kind sled with a common 480 volt bus at the bottom and 30, 100 and 200 amp disconnects installed above. The arc flashes were created by placing a tool or wire across all three phases. Arcs were created with no manikins to fully capture the arc event, manikins wearing non-FR cotton and poly/cotton, and manikins outfitted in INDURA® Ultra Soft® flame resistant clothing, both new and after 100 industrial launderings.
Dozens of safety professionals and engineers from many Fortune 500 companies were in attendance along with many union representatives to experience the serious implications of an electric arc flash first-hand.
The testing clearly demonstrated that if you work on or near energized parts, flame resistant protective apparel and other PPE can and does dramatically reduce injury and save lives, even in what some consider “small” arc flashes.
One of the most surprising things to many of the attendees was the performance, or lack of performance, of 100-percent non-FR cotton. We all clearly saw that non-FR cotton is every bit as dangerous as synthetic blends in even a relatively small arc flash. Clothing made of non-FR cotton ignites just as easily, burns hotter, is much, much harder to extinguish. Since it is typically heavier, it provides more fuel for a longer fire. Attendees agreed afterward that 100-percent non-FR cotton is not an upgrade, and is not appropriate clothing for working on or near energized electrical equipment, no matter how low the predicted incident energy.
Selection processWhen it comes to selecting the proper arc flash PPE, many companies look for suppliers that offer the lowest purchase price. While this is a reasonable practice for some items, it cannot be the prime criteria when it comes to personal protective equipment. The quality of the PPE must be high and long lasting; therefore I recommend that companies investigate further rather than simply purchasing a low-cost product that “meets the standards.” Since the FR fabric is the key contributor to the protection of the garment, as well as much of the comfort and value equations, fabric should be the primary consideration and first decision when selecting arc flash PPE.
The purchase and implementation of an arc flash PPE program represents a significant investment in the safety and health of your workforce. Since worker safety is at stake, and the clothing (and contracts) typically last three to four years, it is prudent to be cautious and thorough before finalizing your specifications. We used a list of key questions to guide our process; I’ve listed them below in order of importance:
- What material (brand of FR fabric) do we specify for our garments?
- Is the company a reputable firm with a track record of making high quality flame resistant fabrics on a consistent basis for many years?
- How have its FR capabilities been tested?
- Has it been subjected to electric arc flash testing, over time, at independent labs?
- Does it have a significant history of market-proven performance?
- What brand and style clothing do we specify?
- Do we want a service provider (laundry, etc), and if so, who?
- How will we roll out implementation and train our wearers?
Some companies make these decisions on a site-by-site basis, but I believe arc flash PPE is too important, and the risks of no program or a poor program are too high, for a decentralized, piecemeal approach to be viable. Thus, my company applies the 70E standard globally, and across business units, to establish top quality and consistent protective clothing norms; we require HRC 2 clothing as daily wear, with a minimum arc rating of 8 cals.
This is about providing the best protection for our employees, in a product that’s as comfortable as their regular clothing, at the best value for our company.