UL-1690:2015 pdf free download – STANDARD FOR SAFETY Data-Processing Cable.
13.2.4 The methods of preparation of samples, of selection and conditioning of specimens, and of making the measurements and calculations for ultimate elongation and tensile strength shall be as indicated under the heading “Physical Properties of Insulation and Jacket” in the Reference Standard for Electrical Wires, Cables, and Flexible Cords, UL 1581, with the modification that ECTFE and ETFE insulations with band-marking inks may have the ink removed before specimens are aged.
13.3 Thicknesses
13.3.1 The dimensions of the spacer (thread) portion of the material insulation in an air-gap coaxial member are not specified. The average thickness and the minimum thickness at any point of the tube portion of an air-gap coaxial member shall not be less than indicated in Table 13.4. The thicknesses of the integral insulation (solid) and jacket on a flat, parallel cable shall not be less than indicated in Table
13.5. The average thickness and the minimum thickness at any point of solid insulation (including any skin) in a coaxial member, and on every other conductor, including each conductor in jacketed ribbon cable before and after separation and in nonintegral flat cable, shall not be less than indicated in Tables 13.2, 13.3, and 13.4. The thicknesses of foamed insulation (including any skin) shall be evaluated based on the performance of the finished cable when tested in accordance with this standard. In any case, the thicknesses of solid and foamed insulations (including any skin) are to be determined by means of measurements made as described in Section 250 of UL 1581, with the following modifications for stranded conductors that leave one or more strand impressions in the insulation that are too small to accommodate the smaller pin referred to in 250.11 of UL 1581, which is to be 0.0200 in (20.0 mils) or 0.508 mm in diameter:
a) The 0.003-in (3-mu) or 0.08-mm thickness-reduction allowance mentioned in 250.5 of UL
1581 is to be applied only to insulation that is from a stranded conductor as mentioned above and has an average thickness (including any skin) of at least 0.015 in or 0.38 mm.
b) Only an optical method as applicable from 13.3.2 and 13.3.3 is to be used for thickness
measurements of insulation that is from a stranded conductor as mentioned above and has an average thickness (including any skin) less than 0.015 in or 0.38 mm.
13.3.2 Thickness measurements of a nylon or similar covering or of insulation having an average thickness or minimum thickness at any point of not more than 0.0060 in or 0.152 mm (including any skin) are to be made by means of a micrometer microscope or other optical instrument that is calibrated to read directly to at least 0.000 1 in (0.1 mil) or 0.00 1 mm. Each of these measurements is to be recorded to the nearest 0.0001 in or 0.001 mm. Otherwise, under 13.3.1 (b), a simply manipulated optical device that is accurate to 0.001 in (1 mil) or 0.01 mm may be used for insulation, with each measurement recorded to the nearest 0.001 in or 0.01 mm.
13.3.3 For 13.3.1 (b), the conductor and any covering over the insulation or skin are to be removed from the finished insulated conductor, wire, or member. A thin slice of the insulation plus any skin is then to be cut perpendicular to the longitudinal axis of the resulting hollow tube. Measurements are to be taken of the maximum and minimum wall thicknesses of the slice. The recorded maximum and minimum thicknesses are to be added together and divided by 2 without any rounding off of the sum but with the resulting average rounded off (see 13.3.4 — 13.3.7) to the same degree as stated in 13.3.2 for the recorded measurements. The average thickness so determined and the recorded minimum thickness are to be taken as the average and minimum-at-any-point thicknesses that are to be compared with the applicable Table 13.2 — 13.5 or with whatever lesser thicknesses are established for the construction as the result of the insulation-crushing test described in Section 27.