When a gas is exposed to a voltage larger than the insulating capacity of the gas, electrical arcs may form. When the voltage is high enough to ionize the space between the conductors, an arc will develop. Air that has been ionized becomes a better conductor, enabling electricity to flow through it. Ionization of the air causes a current to flow, which produces heat and intense light. The ionized air rises and forms an arch-shaped stream because of this heat, giving origin to the phenomenon's name. An arc flash may reach a temperature of 20,000 degrees Celsius. 

Electrical arcs develop when a gas is exposed to a voltage greater than the voltage it can block. When the voltage is high enough to ionize the air between the conductors, the arc starts to form. When a gas is ionized, it transforms into a superb conductor, enabling the flow of electricity and creating an "arc flash." An arc fault is an unintentional electrical discharge.