High-voltage transformer fire barriers

Outdoor transformer fire barriers that are attached at least on one side to a building are referred to as wing walls.

The primary North American document that deals with outdoor high-voltage transformer fire barriers is NFPA 850.

[1] NFPA 850 outlines that outdoor oil-insulated transformers should be separated from adjacent structures and from each other by firewalls, spatial separation, or other approved means for the purpose of limiting the damage and potential spread of fire from a transformer failure.

Instead of a passive barrier, fire protection water spray systems are sometimes used to cool a transformer to prevent damage if exposed to radiation heat transfer from a fire involving oil released from another transformer that has failed.

[4] Transformer oil is available in with sufficiently low combustibility that a fire will not continue after an internal electrical fault.