Applies to air-break switches, air-break isolators and fuse-combination units for use in distribution circuits and motor circuits, the rated voltage of which does not exceed 1000 volt a.c. or 1200 V d.c. It covers classification and characteristics of equipment, markings and instructional information, constructional and performance requirements and testing. Appendices deal with information required when operating conditions differ from standard conditions, clearance and creepage distances, equipment for direct switching of individual motors, and adjustment and measurement of frequency and amplitude of transient recovery voltage.