(a) Where more than six pairs are needed initially, and where an aerial service is necessary, the service shall consist of 22 AWG filled aerial cable of a pair size adequate for the ultimate anticipated service needs of the building. The cable shall comply with the requirements of § 1755.390, RUS specification for filled telephone cables, and shall be RUS accepted or RUS technically accepted.
(b) Aerial cable services shall be constructed in accordance with specific installation specifications prepared by the RUS borrower or the engineer delegated by the borrower.
(c) Unless otherwise specified in the installation specifications, aerial cable service installations shall meet the following requirements:
(1) Strand supported lashed construction shall be used.
(2) Where practicable a 5/16 in. (8 mm) utility grade strand and automatic clamps shall be used in slack spans to avoid damage to the building.
(3) Construction on poles shall comply with applicable construction drawings for regular line construction. Aerial service cable shall be spliced to the main cable in accordance with § 1755.200, RUS standard for splicing copper and fiber optic cables.
(4) Where practicable, aerial cable shall pass under electrical guys, distribution secondaries, and services.
(5) The suspension strand shall be attached to the building by wall brackets as indicated in Figure 7 as follows:
(i) If taut spans are necessary, appropriate size strand may be used if the pull is in line with one wall of the building, or within 20 degrees of being in line as illustrated in sketch A of Figure 7. If the angle of pull is greater than 20 degrees from the building, the wall bracket shall be reinforced against pullout by an arrangement equivalent to sketch B of Figure 7. Taut spans may be strung using the recommendations in RUS Bulletin 1751F-630, Design of Aerial Plant. The same tension as would be used in normal line construction so as not to exceed 60 percent of the breaking strength of the strand under maximum loading shall be used. Taut spans shall not exceed 100 ft (30.5 m) in length and the cable weight shall not exceed 1 pound/foot (lb/ft) [1.5 kilogram/meter (kg/m)] except when equivalent combinations of greater span lengths with cable weight less than 1 lb/ft (1.5 kg/m) are permissible. Copies of RUS Bulletin 1751F-630 are available upon request from RUS/USDA, 1400 Independence Avenue, SW., STOP 1522, Washington, DC 20250-1522, FAX (202) 720-4120.
(ii) When an attachment must be made to the face of a building wall away from a corner, a “U” type wall bracket shall be used as indicated in sketch C of Figure 7. Only slack span construction with 5/16 in. (8 mm) utility grade strand shall be permitted in this situation. The bail of the automatic clamp shall be protected by a wire rope thimble.
(6) Aerial cable shall be located on the rear or side of the building and shall be run only in a horizontal or a vertical direction. The cable route shall be selected so as to avoid building projections and obstructions to the extent practicable.
(7) Cable attachment devices shall be located on solid masonry or on studs of wood frame buildings. Cable attachment devices may be installed on sheet surface materials only when such materials are reinforced with a backing material which allows penetration and firm holding of the attachment devices through the backing material.
(8) The minimum separation on or in buildings between cable and other facilities shall be as indicated in § 1755.505(f)(8), Table 1.
(9) On horizontal runs, cable clamps shall be placed so that the attachment is below the cable. On vertical runs, cable clamps shall be placed so that the attachment is on the same side as horizontal runs. Cable clamps shall be placed on the inside of cable bends.
(10) On horizontal runs, cable clamps shall be placed not more than 16 in. (400 mm) apart for cable diameters equal to or greater than 1 in. (25.4 mm) and 24 in. (600 mm) apart for cable diameters less than 1 in. (25.4 mm).
(11) On vertical runs, cable clamps shall be approximately 24 in. (600 mm) apart for all sizes of cable.
(12) For the cable entrance, holes shall be bored slightly larger in diameter than the cable and shall slope upward from outside to inside. A duct sealer having RUS acceptance or RUS technical acceptance shall be applied to both ends of the hole after the cable is pulled in.