A circuit in which some unplanned event, such as the failure of a component or a stray piece of metal bridging two live contacts, has reduced the resistance in the circuit, resulting in increased current flow through the circuit. It can be said that a complete short circuit has zero resistance and consequently infinite current flow, however, AC line voltage will limit this to either 120V or 240V, which is plenty of current by which to get dead. In anticipation of these accidents, most devices have fuses or other componentry integral to the device and/or its power supply which are designed to fail, breaking the circuit, in the presence of abnormally high voltage.