Receptacles are provided with a safety-interlock system. Plugs cannot be inserted or removed unless the power switch is in the OFF position. The Safety-Interlock is designed to free both hands for insertion and removal of the plug. A cover interlock is provided to prevent entry to the enclosure while the operator is in the ON position. Uses standard Powerlifter ACP or CPH plugs for wide acceptability. Furnished with rugged cast aluminium housings. Flip cap standard and screw cap provided at no additional cost to meet TYPE 4X applications (screw cap not available on 30 amp). Receptacles with 3 phase 4 wire grounded receptacles are prewired to the breaker or disconnect switch. Patented brass receptacle contacts exert constant pressure for good electrical continuity. Appleton’s insulating blocks provide the greatest dielectric and mechanical strength. Ergonomically designed yet rugged cast aluminium handle for exceptional durability and corrosion resistance. 600 VAC FB circuit breakers. Provision is made for locking the operating mechanism in the OFF position.