Arc Flash: Not Just a Flash in the Pan
The electrical arc – you’ve seen it dozens of times. It’s the flash of sparks when a welder joins two pieces of metal together or when a transformer blows, the blast of light and heat, strong enough to melt a car. It’s a constant danger for those working around electrical switch gear equipment, transformers, power stations and new construction utility junctions. What are the dangers of arc flash and what is the best way to avoid arc flash to start with, especially when working around utility poles and underground power lines?
An electrical arc can produce temperatures over 30,000 degrees Fahrenheit. An arc flash results from an arcing fault, where the electric arcs and resulting radiation and shrapnel cause severe skin burns, hearing damage, eye injuries and even lung damage. To give some perspective, clothing ignites and burns when exposed to temperatures over 752 degrees, while a skin burn caused by anything over 176 degrees Fahrenheit is considered a lost cause. The potential for serious injury is real.
More and more, the risk for arc flash has been growing, as transformers and utility junctions age and new construction is increasing the number of commercial and industrial subcontractors working for utilities; recent statistics show that the number of those injured by arc flash continues to grow year over year. Skin damage, which is the most common type of injury caused by arc flash, is based on the intensity of the heat generated by the arc. The amount of heat reaching the skin depends on the power of the arc, the distance of the worker from the arc and the length of time the skin is exposed to the arc.
Inhalation injuries come a close second to skin burns as a result of arc flash, as the intense heat from the flash causes metal to melt, releasing super-heated toxic substances into the air, along with melted metal fragments that can be inhaled.
It goes without saying, then, that the dangers of arc flash are real and working smart when dealing with electrical utility junctions and transformers is critical. As a result of the increase in the number of injuries and deaths coming from arc flash, the National Fire Protection Association issued guidelines for preventing arc flash. Among the recommendations are:
- Only qualified, experienced licensed electricians working for authorized utility companies and contractors should work on transformers, utility junctions and power circuits going into industrial/commercial buildings that have not been put into a “safe” work condition.
- Prior to any work beginning, a flash hazard analysis should be conducted, including an infrared scan of the equipment, if possible.
- All authorized workers in the area of potential flash should be equipped with personal protective equipment (PPE) designed specifically to protect against arc flash, including a flash suit.
- Although there is no certification for arc flash, all working on electrical junctions, transformers, utility boxes and other high-intensity electrical equipment should have attended an Arc Flash Training program that is compliant with the NFPA 70E and OSHA guidelines.
Working safely is the best way to minimize the dangers of arc flash, so before you even start working around areas with the potential for arc flash:
- Ensure your personal protection equipment is in good repair and is donned according to specifications.
- You are adequately grounded, especially if working on overhead power lines and transformers.
- You are working as part of a team; no one person should work alone on high-energy electrical utility equipment.
Special permitting is needed to work on high-energy utility equipment, so only those trained and experienced to handle the requirements should even approach the area, which should be cordoned off to reduce the risk of burns.
There are alternative equipment choices that can be made to avoid or eliminate the possibility of arc flash, such as using metal-clad or arc-resistant switchgear, designed to reduce the incidents of arc, or current-limiting breakers or reactors.
Regardless of the source, arc flash is a real possibility when working with electrical utility equipment, transformers, power stations and the like, so take steps to ensure you and those around you are safe from the danger and only allow licensed, experienced personnel to handle situations where arc flash could be a concern.