A storage battery must supply at least what percentage of the system voltage for legally required standby power?

In the context of legally required standby power, a storage battery must supply at least 87.5% of the system voltage. This requirement is in place to ensure that the standby power source can effectively support the essential loads during an outage. Specifically, this percentage helps maintain the operational integrity of critical systems, ensuring that they receive adequate voltage to function properly without risking malfunction or disruption.

Choosing this percentage is significant because it takes into account voltage drop and variations that can occur during operation. By specifying a minimum of 87.5%, the regulation provides a buffer to accommodate these variations, ensuring reliable power delivery to systems that are essential for safety and continuity during emergencies. Thus, in situations where standby power is required, adhering to this percentage is crucial for compliance and operational reliability.