This is the fifth post in a six-part “Fundamentals of Arc Flash” series. Check back regularly to read new posts offering valuable information on topics such as arc flash causes and characteristics, ratings, and analysis.
An arc flash event poses significant danger to anyone working on or near energized electrical equipment. An electrical fault, or short-circuit, can result in an enormous release of energy, with potentially deadly heat and molten metal projecting outward for significant distance at high speeds.
How much heat, exactly?
Well, if you regard the temperature on the surface of the sun (approximately 9000 degrees Fahrenheit) as the “standard” for ultra-extreme heat, consider this: Based on extensive testing, it is estimated that an arc flash can generate temperatures at the arc terminals that can reach 35,000 degrees – four times hotter than the surface of the sun!
For more, take a listen to Tyndale’s VP Technical, Scott Margolin’s explanation:
Even at the lower estimates of 5,000 to 10,000 o F, unprotected or non-FR exposure to temperatures that high can result in catastrophic injuries or death. Non-flame resistant clothing, including 100% cotton, can and often does ignite. Clothing ignition can generate a perfect storm of bad results. First, much more of the body surface can be burned as the fire spreads to areas the arc didn’t impact. In addition, clothing ignition can lead to more severe burns because the clothing fire lasts much longer than the arc. And, finally, victims are often subject to respiratory issues due to the increased likelihood of breathing in fire and/or toxic gases as clothing burns far longer than an arc that lasts a fraction of a second.
But even with protective clothing, an arc flash can lead to burns if the arc energy is larger than the AR (arc rated) clothing is tested to withstand. The two keys to protecting against burns are:
- Wear arc rated FR clothing (called AR), NOT cotton or other flammable clothing.
- Ensure that the arc rating of the clothing exceeds the anticipated incident energy.
Make sure everyone working within the potential arc flash incident zone is wearing the appropriate AR clothing. This can be achieved by wearing a single layer whose arc rating is high enough to withstand the highest anticipated energy release, or by layering.
Is layering a better option? All AR clothing can break open if exposed to enough energy. If it does, it can ignite a non-FR undergarment or burn exposed skin. It’s not common, but it does occur. This risk combined with vast improvements in weight, softness, price, moisture wicking, and selection of base layer garments, has the industry trending toward AR base layers.
An arc flash that can generate temperatures hotter than the surface of the sun is a frightening possibility. It’s easy to see why catastrophic or fatal injury can result. And it’s equally easy to see why it’s so important to accurately assess potential hazards and then take the steps necessary to protect yourself and your workers from a worst-case scenario.
Want to learn more? Browse our blog posts for more helpful information about protecting workers with FRC and the answers to other frequently-asked questions. Plus, find out about FRC product options and how our managed program can help you maximize compliance and protection while enhancing service and satisfaction.
Have additional questions? Schedule a complimentary 15-minute technical session with Scott Margolin, Tyndale’s Vice President of Technical. Simply complete the form below and Scott will contact you at a mutually agreeable time to speak one-on-one: