In a sprinklered room, air-cooled/dry transformers are rated for how long?

The correct duration for air-cooled or dry transformers in a sprinklered room is one hour. This rating is significant for ensuring that the transformers are not only resistant to potential fire exposure but also remain safe for operation without immediate risk of ignition or structural compromise due to heat.

In a sprinklered environment, the assumption is that the system is designed to minimize fire risk effectively, and one hour is deemed sufficient for these transformers to operate safely under the heaviest anticipated fire conditions. This is particularly relevant for maintaining operational integrity and preventing catastrophic failures that might occur in the event of a fire.

Other durations, such as two hours or more, may be more applicable to different types of equipment or in settings where extended fire exposure is a concern, but for air-cooled or dry transformers, one hour is universally recognized as compliant with safety standards in sprinklered rooms.