(4) Fiber optic cable bond connections. (i) The cable shield and metallic strength members shall be bonded at each splice location. Only RUS accepted fiber optic cable shield bond connectors shall be used to provide bonding connections to the metallic cable shields. The shield bond connector manufacturer's instructions shall be followed concerning installation and use.

(ii) Shield bonding conductors shall be either stranded or braided tinned copper wire equivalent to a minimum No. 6 American Wire Gauge (AWG) and shall be RUS accepted. The conductor connections shall be tinned or of a compatible bimetallic design to avoid corrosion problems associated with dissimilar metals.

(5) Grounding. (i) Grounding is electrically connecting metallic telephone hardware to a National Electrical Safety Code (NESC) acceptable grounding electrode. Acceptable grounding electrodes are defined in the Rule 99A of the NESC.

(ii) The conductor used for grounding metallic telephone hardware shall be a minimum No. 6 AWG solid, bare, copper conductor.

(iii) For copper and fiber optic cable plant, all cable shields, all metallic strength members, and all metallic hardware shall be:

(A) Grounded at each splice location to a driven grounding electrode (ground rod) of:

(1) At least 1.5 meters (5 feet) in length where the local frost level is normally less than 0.30 meters (1 foot) deep; or

(2) At least 2.44 meters (8 feet) in length where the local frost level is normally 0.30 meters (1 foot) or deeper; and

(B) Bonded to a multi-grounded power system neutral when the splice is within 1.8 meters (6 feet) of access to the grounding system of the multigrounded neutral system. Bonding to the multi-grounded neutral of a parallel power line may help to minimize telephone interference on long exposures with copper cable plant. Consideration, thus, should be given to completing such bonds, at least four (4) times each mile, when splices are greater than 1.8 meters (6 feet) but less than 4.6 meters (15 feet) from access to the multi-grounded neutral.

(6) Bonding and grounding splice cases. (i) Splice cases are equipped with bonding and grounding devices to ensure that cable shields and metallic strength members maintain electrical continuity during and after cable splicing operations. The splice case manufacturer's recommendations shall be followed concerning the bonding and grounding procedures. Conductors used for bonding shall be either stranded or braided tinned copper wire equivalent to 6 AWG. Conductors used for grounding shall be a solid, bare, copper wire equivalent to minimum No. 6 AWG.

(ii) Buried splice cases installed in either handholes or pedestals shall be grounded such that the cable shield grounds are attached to a common ground connection that will allow the lifting of a ground on the cable shield in either direction to permit efficient cable locating procedures. As a first choice, buried grounding conductor(s) shall be bare. However, if two or more grounding conductors are buried in the s they shall be insulated to avoid shorts when a locating tone is applied. (iii) A typical bonding and grounding method for fiber optic splices is shown in Figure 19:

(7) Bonding and grounding central office cable entrances. The RUS Telecommunications Engineering and Construction Manual (TE&CM) Section 810 provides bonding and grounding guidance for central office cable entrances. Splicing operations shall not be attempted before all metallic cable shield and strength members are bonded and grounded.

[60 FR 5097, Jan. 26, 1995; 60 FR 9079, Feb. 16, 1995]

§§ 1755.201-1755.369 [Reserved]

§ 1755.370 RUS specification for seven wire galvanized steel strand.

(a) RUS incorporates by reference ASTM A475-78, Standard Specification for Zinc-Coated Steel Wire Strand, issued May 1978. All seven wire galvanized steel strand purchased after April 1, 1990, for use on telecommunications systems financed by RUS loan funds must conform to this standard. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 on January 19, 1990). Copies of ASTM A475-78 are available for inspection during normal business hours at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC, and at the Rural Utilities Service, Administrative Services Division, room 0175-S, U.S. Department of Agriculture, Washington, DC 20250, telephone 202-382-9551. Copies are available from the American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103, telephone 215-299-5400.

(b) In addition to the requirements of ASTM 475-78, all coils and reels having Class B or C coatings shall be marked with a 3-inch wide and 6-inch long deep-colored stripe, green or orange, respectively, to identify the class of galvanized coating of the strand. This marking shall be applied to the exposed convolutions of the strand in the eye of the coils and located near the midpoint on the outside layer of strand on the reels. The marking shall not cover any welded joint markings.

[55 FR 1792, Jan. 19, 1990; 55 FR 3685, Feb. 2, 1990. Redesignated at 55 FR 39397, Sept. 27, 1990]

§§ 1755.371—1755.389 [Reserved]

§ 1755.390 RUS specification for filled telephone cables.

(a) Scope. (1) This section covers the requirements for filled telephone cables intended for direct burial installation either by trenching or by direct plowing, for underground application by placement in a duct, or for aerial installations by attachment to a support strand.

(i) The conductors are solid copper, individually insulated with an extruded solid insulating compound.

(ii) The insulated conductors are twisted into pairs which are then stranded or oscillated to form a cylindrical core.

(iii) For high frequency applications, the cable core may be separated into compartments with screening shields.

(iv) A moisture resistant filling compound is applied to the stranded conductors completely covering the insulated conductors and filling the interstices between pairs and units.

(v) The cable structure is completed by the application of suitable core wrapping material, a flooding compound, a shield or a shield/armor, and an overall plastic jacket.

(2) The number of pairs and gauge size of conductors which are used within the RUS program are provided in the following table: