For legally required standby systems, what is the maximum time allowed for standby power to be available after a normal supply failure?

The correct answer is based on the regulations governing standby systems, which are designed to ensure that essential functions can continue in the event of a power failure. For legally required standby systems, the standard typically mandates that standby power must be available within 60 seconds following a failure in the normal power supply. This timeframe is set to minimize the disruption caused by power outages, particularly in settings such as hospitals, emergency lighting systems, communication centers, and other critical infrastructure where immediate power restoration is crucial for safety and operation.

Choosing this timeframe allows for a balance between the needs for reliability and the practicality of implementation. Systems designed to meet this requirement are often equipped with automatic transfer switches and backup generators that can rapidly engage to provide the necessary power, ensuring that critical systems remain operational with minimal delay.