External Manual Bypass Switch: The manually operated make-before-break bypass switch is located in a separate enclosure from the UPS. Commonly, the separate enclosure is wall mounted or in a matching sidecar cabinet to the UPS. Similar to the internal bypass switch, the UPS load can be seamlessly transferred between the UPS and bypass power source. The External manual bypass switch totally isolates the UPS from the AC power source. This allows the UPS to be de-energized for service and even physically removed or reinstalled without interrupting power to the critical load. External rack mount manual bypass switches are typically used on UPS and Inverters that are designed to also be mounted in racks.
PROS: Not only can the UPS be completely de-energized, but the UPS can also be physically removed for servicing. All internal components are de-energized. This is the most desirable bypass configuration for service accessibility and safety.
CONS: Bypass Switch must be mounted externally and may require more floor or wall space.