Electrical hazards are usually present as we perform many of our work tasks.  An arc flash (also called a flashover), which is distinctly different from the arc blast, is part of an arc fault (short), a type of electrical explosion that results from a low-impedance connection to ground or another voltage phase in an electrical system. What is Arc Flash? An arc flash is the light and heat produced from an electric arc supplied with sufficient electrical energy to cause substantial damage, harm, fire, or injury.  As an arc develops and gets hotter, the resistance drops, drawing more and more current (runaway) until some part of the system melts, trips, or evaporates, providing enough distance to break the circuit and extinguish the arc.  When an uncontrolled arc forms at high voltages, arc flashes can produce deafening noises, supersonic concussive-forces, super-heated shrapnel, temperatures far greater than the Sun’s surface, and intense, high-energy radiation capable of vaporizing nearby materials.  Arc flash temperatures can reach or exceed 35,000 °F (19,400 °C) at the arc terminals. The massive energy released in the fault rapidly vaporizes the metal conductors involved, blasting molten metal and expanding plasma outward with extraordinary force.  The result of the violent event can cause destruction of equipment involved, fire, and injury not only to an electrical worker but also to bystanders. During the arc flash, electrical energy vaporizes the metal, which changes from solid state to gas vapor, expanding it with explosive force. For example, when copper vaporizes it suddenly expands by a factor of 67,000 times in volume. When can it occur? One of the most common causes of arc flash injuries happens when switching-on electrical circuits and, especially, tripped circuit-breakers. A tripped circuit-breaker often indicates a fault has occurred somewhere down the line from the panel. The fault must usually be isolated before switching the power on, or an arc flash can easily be generated. Small arcs usually form in switches when the contacts first touch, and can provide a place for an arc flash to develop. If the voltage is high enough, and the wires leading to the fault are large enough to allow a substantial amount of current, an arc flash can form within the panel when the switch is turned on. Generally, either an electric motor with shorted windings or a shorted power-transformer are the culprits, being capable of drawing the energy needed to sustain a dangerous arc-flash. Circuit breakers are often the primary defense against current runaway, especially if there are no secondary fuses, so if an arc flash develops in a breaker there may be nothing to stop a flash from going out of control. Once an arc flash begins in a breaker, it can quickly migrate from a single circuit to the phases of the panel itself, allowing very high energies to flow. Precautions must usually be used when switching circuit breakers, such as standing off to the side while switching to keep the body out of the way, wearing protective clothing, or turning-off equipment, circuits and panels downline prior to switching. Very large switch gear is often able to handle very high energies, and, thus, many places require the use of full protective equipment before turning it on. Other causes of Arc Flash include:

• dust,
• dropped objects (tools or bolts),
• accidental contact (humans & small animals),
• condensation,
• material failure,
• corrosion,
• faulty installation, or
• verifying an electrically safe work condition after Lock out Tag out (LOTO) has been completed.

What are the potential personal impacts? Ignition of flammable clothing, shock, electrocution, first-degree burns, second-degree burns, third-degree burns, fourth degree burns, inhalation of molten Copper vapor, temporary blinding flash, hearing loss from explosive sound waves, and pressure waves creating projectiles or blasting a worker back into other objects (walls, handrails, operating equipment) are all potential impacts. How to protect yourself and your coworkers?

• Do not work on electrical equipment unless you are properly trained and qualified to do so.
• Treat all electrical components as “live” until proved to be in an electrically safe work condition. (note: the workers performing the de-energized verification must treat the equipment as energized until the testing process confirms an electrically safe work condition)
• Ensure the workforce follows Electrical Safety-Related Work Practices while working on electrical equipment.
• Stay out of the immediate work areas or barricaded areas for electricians and maintenance personnel working on electrical equipment.

PPE? There are many methods of protecting personnel from arc flash hazards. This can include personnel wearing arc flash personal protective equipment (PPE) or modifying the design and configuration of electrical equipment. The best way to remove the hazards of an arc flash is to de-energize electrical equipment when interacting with it, however de-energizing electrical equipment is in and of itself an arc flash hazard. In this case, one of the newest solutions is to allow the operator to stand far back from the electrical equipment by operating equipment remotely, this is called remote racking NFPA 70E provides guidance on implementing appropriate work practices that are required to safeguard workers from injury while working on or near exposed electrical conductors or circuit parts that could become energized.  For assistance, reach out to a Stratus electrical champion.