MIL-HDBK-1012/3

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EXAMPLE TWO (Continued)

B. Feeder Ducts. For estimating purposes a standard feeder duct

of 50 sq. cm (8 sq. in.) may be allotted for each 80 sq. m

(800 sq. ft.) of usable floor space (typical area feeder duct

will service).

1.

Calculate:

(a)

Number of feeder ducts = usable floor space divided

by 800 sq. ft.

Number of feeder ducts = usable floor space =

800 sq. ft.

Example:

If the usable floor space is 10,000 sq. ft. then:

Quantity of feeder ducts = 10,000 sq. ft.

800 sq. ft.

= 12.5

round up to = 13

(b) Total length of feeder ducts = number of

feeder ducts times their average length (distribution

area width/4 or 2).

(1) For a centrally located telecommunications

closet, divide the width of the distribution zone by 4 and

multiply by the number of feeder ducts required:

Total length of feeder duct = (width) x no. of ducts

=

4

30