What qualifies as a scenario requiring a PDP tie?

A power loss downstream of the Central Distribution Board (CDB) is a scenario that can necessitate a PDP tie. This situation typically indicates that there is an interruption in the electrical supply, which can affect equipment or systems dependent on that power. In order to restore service or maintain continuous operation, a PDP (Power Distribution Panel) tie becomes critical. It allows for an alternative routing of power, ensuring that loads can still receive the necessary electricity even if one pathway is compromised.

In contrast, scheduled maintenance work is usually planned and allows for existing systems to be shut down without immediate concern for power loss. Battery replacement, while important for system reliability, is typically a routine maintenance activity that may not necessarily require a tie if it is conducted during scheduled downtime. Voltage testing, while necessary for system assessments and safety, does not typically involve the need to re-route power or engage backup systems. Therefore, the correct answer focuses on circumstances where there is an actual disruption in service, highlighting the importance of managing electrical distribution in real-time scenarios.