UFC 3-600-01
17 April 2003
with change 16 January 2004
Table 6-4 (Army)
SEPARATION DISTANCE BETWEEN OUTDOOR FLUID
INSULATED TRANSFORMERS and EQUIPMENT (INCLUDING
OTHER TRANSFORMERS)
Transformer Rating
Distance
Liquid
KVA
ft (m)
Less Flammable
<2000
5 (1.5)
>2000
25 (7.6)
Mineral Oil
<1,000
5 (1.5)
(transformers made after
>1000
25 (7.6)
1970, except zigzag-type)
<650
5 (1.5)
Mineral Oil
650 6500
25 (7.6)
(transformers made before
1970 & zigzag-type)
>6500
50 (15.2)
6-27.2.2.2.2 Fire Barriers. Fire barriers must be of concrete block or reinforced
concrete construction adequate for 2-hour fire resistance.
6-27.2.2.2.2.1
Buildings.
6-27.2.2.2.2.1.1
When building walls are used for protection, the exposed
wall must extend the horizontal and vertical distances from the transformer
specified in Table 6-1 or Table 6-2.
6-27.2.2.2.2.1.2
Roofs exposed to mineral oil insulated transformers must be
Class A rated for the exposed area. The exposed area is considered to be the
following:
5,000 gallons of mineral oil where roofs are less than 7.76 m (25 ft)
high.
7.6 m (25 ft) from a transformer containing more than 19 m3 (5,000
gallons) where roofs are less than 15 m (50 ft) high.
6-27.2.2.2.2.2
Equipment. For equipment, barriers must extend 0.3m (1 ft)
vertically and 0.6m (2 ft) horizontally beyond transformer components that could
be pressurized as the result of an electrical fault. This will typically include
bushings, pressure relief vents, radiators, tap changer enclosures, and other
similar devices.
6-27.2.2.2.3 Water Spray Exposure Protection.
6-27.2.2.2.3.1
Buildings.
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