IEC 60309-1 Ed. 4.0 b:1999

Applies to plugs and socket-outlets, cable couplers and appliance couplers, with a rated operating voltage not exceeding 690 V d.c. or a.c, 500 Hz a.c. and a rated current not exceeding 250 A, primarily intended for industrial use, either indoors or outdoors when the ambient temperature does not normally exceed 40°C.