This specification prescribes safety requirements for air-break switches having a rating up to and including 300 amperes designed for direct manual operation to a self-sustained position by means such as a handle, lever, push-button, or turn-knob, for use in accordance with Part 1 of the SAA Wiring Rules in electrical circuits operating at low or medium voltage. The scope of this specificationincludes such switches as single-pole and multi-pole switches for use in electrical installations and equipment, switches built into appliances, multi-heat switches, and miniature switches both of the snap-action and slow-break type. The specification covers switches having various types of enclosure, such as general-purpose, weatherproof, flameproof, or dustproof.