An arc flash is the light and heat produced as part of an arc fault (sometimes referred to as an electrical flashover), a type of electrical explosion or discharge that results from a connection through air to ground or another voltage phase in an electrical system. Arc flash is different from the arc blast, which is the supersonic shockwave produced when the conductors and surrounding air are. DefinitionAn arc flash is the light and heat produced from an supplied with sufficient electrical energy to cause substantial damage, harm, fire, or injury. Electrical arcs experience, which caus. Most 400 V and above electrical services have sufficient capacity to cause an arc flash hazard. Medium-voltage equipment (above 1000 V) is higher potential and therefore a higher risk for an arc flash hazard. Hig.