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Unformatted text preview: surface of vaults
constructed of hollow concrete blocks shall have a coating of cement or gypsum plaster
not less than 20 mm thick. the vault shall have a concrete floor not less than 100 mm
thick. Building walls and floors which meet these requirements may serve for the floor,
roof and one or more walls of the vaults. Other forms of fire-resistive construction are
also acceptable provided they have adequate structural strength for the conditions and a
minimum fire resistance of two and one-half hours according to the approved Fire Test
Standard. The quality of the material used in the construction of the vault shall be of the
grade approved by the Building Official having jurisdiction. 9.4 Doorways.
follows: Any doorway leading from the vault into the building shall be protected as 9.4.1 9.4.2 SILLS. A door sill or curb of sufficient height to confine within the vault, the oil
from the largest transformer shall be provided and in no case shall the height be
less than 100 mm. 9.4.3 10. TYPE OF DOOR. Each doorway shall be provided with a tight-fitting door of a
type approved for openings in such locations by the authority enforcing this Code. LOCKS. Entrance doors shall be equipped with locks, and doors shall be kept
locked, access being allowed only to qualified persons. Locks and latches shall be
so arranged that the door may be readily and quickly opened from the inside. Ventilation. Ventilation shall be adequate to prevent a transformer temperature in excess of the
10.1 Ventilation Openings. When required, openings for ventilation shall be provided in
accordance with the following:
10.1.1 LOCATION. Ventilation openings shall be located as far away as possible from
doors, windows, fire escapes and combustible material.
10.1.2 ARRANGEMENT. Vaults ventilated by natural circulation of air may have
roughly half of the total area of openings required for ventilation in one or more
openings near the floor and the remainder in one or more openings in the roof or
in the sidewalls near the roof; or all of the area required for ventilation may be
provided in one or more openings in or near the roof. 10.1.3 SIZE. In the case of vaults ventilated to an outdoor area without using ducts or
flues the combined net area of all ventilating openings after deducting the area
occupied by screens, gratings, or louvers, shall be not less than .006 sq. mm per
KVA of transformer capacity in service, except that the net area shall be not less
than 0.1 sq. m. for any capacity under 50 KVA.
10.1.4 COVERING. Ventilation openings shall be covered with durable gratings,
screens, or louvers, according to the treatment requirement required in order to
avoid unsafe conditions.
10.1.5 DAMPERS. Where automatic dampers are used in the ventilation openings of
vaults containing oil-insulated transformers, the actuating device should be made
to function at a temperature resulting from fire and not a temperature which might
prevail as a result of an overheated transfo...
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This note was uploaded on 09/22/2013 for the course ARIDBE AR taught by Professor Any during the Fall '12 term at Mapúa Institute of Technology.
- Fall '12