Shield.

Shield.
(1) An aluminum shield, plastic coated on one side, shall be applied longitudinally over the core wrap.
(2) The shield may be applied over the core wrap with or without corrugations (smooth) and shall be bonded to the outer jacket.
(3) The shield overlap shall be a minimum of 3 mm (0.125 in.) for cables with core diameters of 15 mm (0.625 in.) or less and a minimum of 6 mm (0.25 in.) for cables with core diameters greater than 15 mm (0.625 in.). The core diameter is defined as the diameter under the core wrap and binding.
(4) General requirements for application of the shielding material shall be as follows:
(i) Successive lengths of shielding tapes may be joined during the manufacturing process by means of cold weld, electric weld, soldering with a nonacid flux, or other acceptable means;
(ii) The metal shield with the plastic coating shall have the coating removed prior to joining the metal ends together. After joining, the plastic coating shall be restored without voids using good manufacturing techniques;
(iii) The shields of each length of cable shall be tested for continuity. A one meter (3 ft) section of shield containing a factory joint shall exhibit not more than 110 percent of the resistance of a shield of equal length without a joint;
(iv) The breaking strength of any section of a shield tape containing a factory joint shall not be less than 80 percent of the breaking strength of an adjacent section of the shield of equal length without a joint;
(v) The reduction in thickness of the shielding material due to the corrugating or application process shall be kept to a minimum and shall not exceed 10 percent at any spot; and
(vi) The shielding material shall be applied in such a manner as to enable the cable to pass the bend test as specified in paragraph (i)(1) of this section.
(5) The dimensions of the uncoated aluminum tape shall be 0.2030±0.0254 mm (0.0080±0.0010 in.).
(6) The aluminum tape shall conform to either Alloy AA-1100-0, AA-1145-0, or AA-1235-0 as covered in the latest edition of Aluminum Standards and Data, issued by the Aluminum Association, except that requirements for tensile strength are waived.
(7) The single-sided plastic coated aluminum shield shall conform to the requirements of ASTM B 736-92a, Type I Coating, Class 1 or 2, or Type II Coating, Class 1. The minimum thickness of the Type I Coating shall be 0.038 mm (0.0015 in.). The minimum thickness of the Type II Coating shall be 0.008 mm (0.0003 in.).
(8) The plastic coated aluminum shield shall be tested for resistance to water migration by immersing a one meter (3 ft) length of tape under a one meter (3 ft) head of water containing a soluble dye plus 0.25 percent (%) wetting agent.
(i) After a minimum of 5 minutes, no dye shall appear between the interface of the shield tape and the plastic coating.
(ii) The actual test method shall be acceptable to RUS.
(9) The bond between the plastic coated shield and the jacket shall conform to the following requirements:
(i) Prepare test strips approximately 200 mm (8 in.) in length. Slit the jacket and shield longitudinally to produce 4 strips evenly spaced and centered in 4 quadrants on the jacket circumference. One of the strips shall be centered over the overlapped edge of the shielding tape. The strips shall be 13 mm (0.5 in.) wide. For cable diameters less than 19 mm (0.75 in.) make two strips evenly spaced.
(ii) Separate the shield and jacket for a sufficient distance to allow the shield and jacket to be fitted in the upper and lower jaws of a tensile machine. Record the maximum force required to separate the shield and jacket to the nearest newton (pound-force). Repeat this action for each test strip.
(iii) The force required to separate the jacket from the shield shall not be less than 9 N (2 lbf) for any individual strip when tested in accordance with paragraph (f)(9)(ii) of this section. The average force for all strips of any cable shall not be less than 18 N (4 lbf).

Source

7 CFR § 1755.870


Scoping language

None
Is this correct? or