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.
An 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. The length of the gaps between the conductive parts, which are bridged by the arc, electrodes, the confinement around the arc, the chemical compositions of the conductors and the materials around the arc, and the distance of the worker from the arc are some of the factors that can sustain an arc flash. 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 flash can cause serious injury or damage, and the intense UV, visible, and IR light produced by the arc can temporarily and sometimes even permanently blind or cause eye damage to people. The rapidly expanding superheated vapor produced by the arc can also cause serious injury or damage. To prevent arc flash, one can use the 4P Model for arc flash hazard management: Predict, Prevent, Protect, Publish. This involves identifying and calculating the potential risks, using principles of prevention to control risks, reducing the risk of injury with proper protection, and collecting information for future workers to reassess changes such as environmental conditions and equipment state.
