An arc flash is an undesired electric discharge...(WhatIs.com)
Arc-flash hazards could lead to deadly consequences in data center
Arc-flash hazards can cause fatal injuries, equ...(SearchDataCenter.com)
With proper control, electric arcs can be harnessed and used industrially for welding, plasma cutting and even certain types of lighting such as fluorescent lighting where a high voltage ionizes the inert gas within a glass tube; the flow of current across the ionized gas liberates visible light. However, for every harnessed electric arc there is an unwanted arc. For example, poorly installed (or poor quality) electrical switches, electrical circuit breakers and other electrical contact points are susceptible to these undesired arcs as contacts are opened and closed.