Arc flashes are a constant concern for workers around electrical equipment. Dozens of arc flash incidents happen every day in the United States, with an average of 400 fatalities every year from arc flash incidents.
As with any type of incident, much of this comes from not fully understanding arc flashes, what they are and what can cause them. By understanding arc flashes, we can help to lessen the risk of injuries from arc flash incidents.
What is Arc Flash?
Arc flash is the light and heat produced as part of an arc fault. An arc fault is defined as “an electrical explosion or discharge that results from a low-impedance connection through air or ground to another voltage phase in an electrical system.
A common example that we’ve all probably seen is what happens when an incandescent light bulb burns out while the bulb is on. When this happens, the filament inside the bulb breaks, but an arc is sustained across the filament. This causes a bright blue flash, often accompanied by a popping sound. If you look at a bulb after it blows out, you are likely to see black speckling on the inside of the bulb.
Arc flash incidents on the industrial or construction site are similar in theory, but they are on a much larger scale. Instead of a pop, a short blue glow, and a discolored bulb, they have much more drastic consequences.
The Dangers from an Arc Flash
There are a number of dangers that come from an arc flash incident, and all of them can cause short-term or lasting injuries to workers affected by the incident.
- Temperatures in an arc flash can reach as high as 35,000 degrees Fahrenheit – producing some of the highest temperatures known to man. By comparison, the surface of the sun only measures up to 9,000 degrees Fahrenheit. This is hot enough to vaporize objects close to the flash, humans included. These are temperatures that can cause severe burns, even if the worker is 10 or more feet away from the flash itself.
- The concussion wave from the arch flash incident can expand quickly, and can throw workers across rooms and knock them off of ladders. Pressure from arc flash waves have been seen to produce more than 2,000 pounds per square foot of pressure, enough to bruise or cause disruption to body systems and damage tissue. This includes lung damage, nerve damage, and potential heartbeat disruption.
- The explosion caused by an arc flash can propel shrapnel at high speeds. This can include tools and parts, but it can also include metal that has been melted by the high temperatures, with metal droplets being propelled up to ten feet from the flash itself. These droplets adhere to clothing or skin and cause deep, severe burns.
- A sound blast from the incident can be loud enough to cause eardrums to rupture, creating short- or long-term hearing problems.
- Photokeratitis – an eye condition that is similar to sunburn, but of the cornea – can cause temporary or long-term vision problems. Referred to as arc eye, but also sometimes called welder’s flash, bake eyes, or snow blindness, this comes from seeing the flash of the arc without the proper eye covering.
Causes of Arc Flash
Arc flash can be caused by a variety of issues, ranging from faulty equipment to worker errors. Potential causes include:
- Improper use of test equipment
- Poorly maintained equipment
- Insulation failure, including gaps or wear and tear
- Loose connections
- Inadvertent contact
- Pests such as small animals and insects entering switchgear through openings
- Accumulation of dust or moisture that can weaken air insulated bus bars
- Faulty operation of a load break switch
- Workers mistakenly dropping tools on live electrical parts
- Obstructions in disconnect panels
- Exposed live parts, loose connection, and corrosion
The Best Ways to Avoid and Eliminate Arc Flash Incidents
The most effective and foolproof way to eliminate the risk of arc flash is to simply de-energize the equipment. But even the process of de-energizing the equipment can cause an arc flash – plus, it is not always possible to have the equipment powered down to conduct service. However, de-energizing remains the most foolproof, guaranteed way to avoid arc flash. Other ways to minimize the rock of arc flash include:
- Redesigning electrical systems and controls to prevent and lessen risk
- Collect data about your facility’s power distribution system and identify where you can use low-risk technology to reduce the chance of arc flash occurring.
- Improve safety training and risk awareness, so your employees and personnel understand the dangers and consequences that come with ignoring safety procedures.
- Identify the risks, boundaries, and suitable PPE for electrical safety through arc flash hazard studies.
One of the best ways to avoid and eliminate injuries from arc flash incidents is to implement and adhere to arc flash boundaries. These boundaries are the minimum safe distances from energized conductors or circuit parts that have a potential for an arc fault. Developed by the NFPA, these are founded on research over the years.The furthest boundary should be the arc flash boundary. This is where, if an arc flash occurs, the worker would be exposed to a maximum of 1.2 calories per centimeters squared of flash energy. This amount should result in no worse than a curable second degree burn to exposed skin.
The limited approach boundary is the distance from a live part where a shock hazard exists. To stand between the arc flash boundary and the limited approach boundary, a worker should have the proper personal protective equipment. An unqualified or untrained person should not approach the potential source any closer than the limited approach boundary.
Restricted space and the restricted boundary is the area directly around the exposed electrical components. The boundary should only be crossed by trained, qualified workers who have undergone required training, and who are equipped with the appropriate PPE. The worker should have a written plan and a work permit for the job.
Photo credit: Wp.com
By understanding these boundaries and explaining them to workers who may work within them or be around them, you can educate everyone on where they should or should not walk. Creating these boundaries and enforcing them can keep workers safe.
Here at PowerPak, we understand the potential issues that can happen with arc flash, which is why we carry a variety of highly-rated visors, kits, and more. From the most basic arc-rated goggles and arc flash balaclava that are rated to 38 cal/cm2, to the full 100Cal. Arc Flash Suit Kit, we carry a great variety of arc flash kits and protection that will fit your PPE needs!
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