The male and female connectors and receptacles covered by this specification are intended for use with ground support and base facility equipment (ramp or wall-mounted outlets) requiring 480/277 VAC. The series 1 connectors and receptacles are for use in non-hazardous locations. The series 2 connectors and receptacles are for use in hazardous (classified) locations. This specification is not intended to include specifications for explosionproof receptacle housings. The series 2 connectors specified herein can be used in enclosures approved for use in hazardous (classified) locations. The receptacle housings for the series 2 receptacle inserts, when used in hazardous (classified) locations, must include a rotatable collar with spring door.