Air-cooled/dry transformers housed in a fire sprinklered room are rated for how many hours?

Air-cooled or dry transformers that are housed in a fire sprinklered room are typically rated for 1 hour. This rating is significant because it reflects the transformer’s capability to withstand exposure to fire for that duration without compromising its functionality or safety features.

The 1-hour rating is indicative of a level of fire resistance that allows for operation during a fire event, thereby providing sufficient time for personnel to respond and manage the situation. The presence of a sprinkler system further enhances safety, as it can help to control or extinguish a fire within that timeframe, making the 1-hour rating both practical and necessary within an appropriately equipped environment.

Higher ratings such as 2 hours or more would generally apply to transformers located in areas without the benefit of sprinkler systems or where additional fire-resistance measures are warranted. Understanding these time ratings is crucial for fire protection and safety planning in facilities using transformers.