are stored.
c. A liquid confinement area is provided.
d. The installation complies with all restrictions pro vided for in the listing of the liquid.

(2) With an automatic fire extinguishing system and a liquid confinement area, provided the transformer is rated 35,000 volts or less

(3) In accordance with 450.26

(B) Outdoor Installations. Less-flammable liquid-filled transformers shall be permitted to be installed outdoors,attached to, adjacent to, or on the roof of buildings,where installed in accordance with (1) or (2):

(1) For Type I and Type II buildings, the installation shall comply with all restrictions provided for in the listing of the liquid.
FPN: Installations adjacent to combustible material, fire escapes, or door and window openings may require additional safeguards such as those listed in
450.27.
(2) In accordance with 450.27.
FPN No. 1: As used in this section, Type I and Type II buildings refers to Type I and Type II building construction as defined in NFFA 220-2006, Standard on Types of Building Construction. Combustible materials refers to those materials not classified as noncombustible or limited-combustible as defined in NFFA 220-2006.
FPN No. 2: See definition of Listed in Article 100.

450.24 Nonflammable Fluid-Insulated Transformers.

Transformers insulated with a dielectric fluid identified as nonflammable shall be permitted to be installed indoors or outdoors. Such transformers installed indoors and rated over 35,000 volts shall be installed in a vault. Such transformers installed indoors shall be furnished with a liquid confinement area and a pressure-relief vent. The transformers shall be furnished with a means for absorbing any gases generated by arcing inside the tank, or the pressure-relief vent shall be connected to a chimney or flue that will carry such gases to an environmentally safe area.
FPN: Safety may be increased if fire hazard analyses are performed for such transformer installations.
For the purposes of this section, a nonflammable dielectric fluid is one that does not have a flash point or fire point and is not flammable in air.

450.25 Askarel-Insulated Transformers Installed In- doors. Askarel-insulated transformers installed indoors and rated over 25 kVA shall be furnished with a pressure-relief vent. Where installed in a poorly ventilated place, they shall be furnished with a means for absorbing any gases generated by arcing inside the case, or the pressure-relief vent shall be connected to a chimney or flue that carries such gases outside the building. Askarel-insulated transformers rated over

35,000 volts shall be installed in a vault.

450.26 Oil-Insulated Transformers Installed Indoors.

Oil-insulated transformers installed indoors shall be in- stalled in a vault constructed as specified in Part III of this article.

Exception No. 1: Where the total capacity does not exceed 112'/2 kVA, the vault specified in Part HI of this article shall be permitted to be constructed of reinforced concrete that is not less than 100 mm (4 in.) thick.

Exception No. 2: Where the nominal voltage does not exceed 600, a vault shall not be required if suitable ar- rangements are made to prevent a transformer oil fire from igniting other materials and the total capacity in one location does not