These external enclosures are designed to house the main power supply on the right side of the main enclosure, keeping the live side of the power supply separate from primary electrical equipment. They enable easy installation of compact fusible disconnect with a rotary handle. The enclosures are designed with a patented cable-operated mechanical interlocking system that requires the main enclosure door to be closed and door handle engaged to turn the disconnect on. Once the main enclosure is closed and disconnect is turned on, the main enclosure is locked automatically. It unlocks when the disconnect is turned off.