An arc flash is a type of electrical explosion or discharge that results from a connection through air to ground or another voltage phase in an electrical system. It is the light and heat produced from an electric arc supplied with sufficient electrical energy to cause substantial damage, harm, fire, or injury. Arc flash is distinctly different from the arc blast, which is the supersonic shockwave produced when the uncontrolled arc vaporizes the metal conductors. Both are part of the same arc fault, and are often referred to as simply an arc flash, but from a safety standpoint, they are often treated separately.
Arc flash can be caused by unintentional contact between an energized conductor, such as a bus bar or wire, with another conductor or an earthed surface. Common causes of arc flash include equipment failure, dropping un-insulated tools or metal parts, using incorrectly specified instruments, live work on damaged equipment such as cables, loose connections, and exposed live parts, and lack of awareness and training.
Arc flashes are extremely dangerous and can cause serious injuries or even death. The violent nature of an arc flash exposure can result in burns, fire, flying objects, and acoustic injuries. Temperatures of an arc flash can reach as much as 35,000 °F, which is more than three times hotter than the sun. The charged particles produced by an arc flash may also be attracted to metallic objects nearby, such as jewelry, belt buckles, keys, and eyeglasses, causing severe burns to the Airways and lungs if inhaled.
To prevent arc flash, it is essential to understand the dangers of working with electricity and take measures to reduce the possibility and severity of hazards. Employers are required by law to estimate incident heat energy of electric-arc hazards and provide exposed workers with the right personal protective equipment (PPE) . Non-compliance with OSHA’s OSH Act exposes employees to serious safety threats and may result in hefty OSHA fines and even imprisonment for employers. Effective training is also essential to reduce the risk of human error.
