The following paragraphs cover the installation of all transformers, except:
Dry-type transformers installed as a component part of other apparatus;
Transformers which are an integral part of an X-ray, high frequency, or electrostatic-coating apparatus;
Transformers used with Class 2 and Class 3 circuits, sign and outline lighting, electric discharge lighting, and power-limited fire-protective signaling circuits.
Dry-type, high fire point liquid-insulated, and askarel-insulated transformers installed indoors and rated over 35 kV shall be in a vault.
If they present a fire hazard to employees, oil-insulated transformers installed indoors shall be in a vault.
Combustible material, combustible buildings and parts of buildings, fire escapes, and door and window openings shall be safeguarded from fires which may originate in oil-insulated transformers attached to or adjacent to a building or combustible material.
Transformer vaults shall be constructed so as to contain fire and combustible liquids within the vault and to prevent unauthorized access. Locks and latches shall be so arranged that a vault door can be readily opened from the inside.
Any pipe or duct system foreign to the vault installation shall not enter or pass through a transformer vault.
Materials shall not be stored in transformer vaults.
The operating voltage of exposed live parts of transformer installations shall be indicated by warning signs or visible markings on the equipment or structure.