450.27 Oil-Insulated Transformers Installed Outdoors
In cases where the transformer installation presents a fire hazard, one or more of the following safeguards shall be applied according to the degree of hazard involved:
- Space separations
- Fire-resistant barriers
- Automatic fire suppression systems
- Enclosures that confine the oil of a ruptured transformer tank
Oil enclosures shall be permitted to consist of fire-resistant dikes, curbed areas or basins, or trenches filled with coarse, crushed stone Oil enclosures shall be provided with trapped drains where the exposure and the quantity of oil involved are such that removal of oil is important.
Informational Note: For additional information on transformers installed on poles or structures or under ground, see ANSI/IEEE C2—2017, National Electrical Safety Code.