Arc ¢ash is a form of hazard that does not involve current passing through a person. This hazard occurs when air is ionized between two points that have enough potential difference to cause an arc between them. This often happens accidentally during maintenance work when tools make contacts with live parts of difference potentials. It can also be caused by dust, water vapor, corrosion, overvoltage, dropping foreign object, misalignment of moving contacts, and intrusion of animals. If the energy in the arc is high, the arc can be deadly as the temperature and pressure caused by it can rapidly increase to excessive values near the work area. In the United States alone, 2000 persons are admitted to hospitals due to arc ¢ash every year.