ETL 1110-3-412
20 Oct 89
Table 7
Fire Protection for Outdoor Oil--Insulated Transformers
SIZE (EACH TRANSFORMER)
NUMBER
PROTECTION
Under 9,999 ~VA
One or more
Portable Extinguishers
10.000 - 99,999 kVA1
One only
Hydrant Protection
10,000 - 99,999 kVA1
More than one
a. Provide a 25-ft. (S m)
minimum clear space
between units, or
b. Noncombustible bamers
between units, or
c. Fixed automatic waterspray
100,000 kVA and above.
One or more fixed automatic
water sprays
10,000 kVA and above
One or more
Fixed automatic water spray
1
Where there are mission-essential bus structures exposed to a possible transformer oil
fire, or electric service or production could be interrupted for an extended period, a fixed
automatic water spray system shall be provided to minimize the physical damage from fire
and reduce the downtime for repairs.
7
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