UL-1424:2015 pdf free download – STANDARD FOR SAFETY Cables for Power-l imited Fire- Alarm Circuits.
7 Insulation
7.1 Material and application
7.1.1 Each conductor shall be insulated for its entire length with one or more of the insulation materials indicated in Table 7.1 or referenced in note a to Table 7.1. The insulation shall be solid or, in the cases indicated in the second column of Table 7.1, may be expanded (foamed). In any case, a solid dielectric skin (a thin, solid, extruded layer that may or may not be separable) of the same or other material from Table 7.1 may be applied over the solid insulation or over the foam. The material insulation in an air-gap coaxial member shall consist of a solid tube over a solid spacer (thread) that has a nominally circular cross section and is applied to the conductor helically in a continuous length (length of lay is not specified). Otherwise, the insulation shall be applied directly to the conductor, shall have a circular cross section, and shall fit tightly to the conductor but shall not adhere excessively (no test). The insulation shall be uniform and shall not have any defects (bubbles, open spots, rips, tears, cuts, or foreign material) that are visible with normal or corrected vision without magnification.
7.1 .2 Either of the following materials that the manufacturer wishes to use as insulation or a jacket shall be evaluated for the requested temperature rating as described in the test Dry Temperature Rating of New materials (Long Term Aging Test) in UL 2556:
a) Material generically different from any insulation or jacket material that is named in Table 7.1 for the construction (new material).
b) Material that is named in Table 7.1 yet does not comply with the short-term tests specified for the material in Specific Materials, Section 50 of UL 1581.
The temperature rating of materials (a) and (b) shall be the temperature rating for the cable determined as specified in 13.1. The thicknesses of insulation and/or jacket using materials (a) and/or (b) shall be as required for the specific cable type. Investigation of the electrical, mechanical, and physical characteristics of the cable using material (a) and/or (b) shall show the material(s) to be comparable in performance to an insulation or jacket material named in Table 7.1 for the required temperature rating. The investigation shall include tests such as crushing, impact, abrasion, deformation, heat shock, insulation resistance, and dielectric voltage-withstand.
7.2 Properties
7.2.1 Unaged and heat-aged insulation requirements for all cables to be rated 60°C
7.2.1.1 Specimens of solid single-layered unaged insulation removed from finished insulated conductors shall have a minimum tensile strength of 1200 lbf/in2 or 8.27 MN/rn2 or 827 N/cm2 or 0.844 kgf/rnm2 and a minimum elongation of 100 percent when tested in accordance with the test Physical Properties (Ultimate Elongation and Tensile Strength) in UL 2556. For all insulated conductor types, specimens approximately 12 inches or 300 mm long shall be placed in a circulating air oven conforming to ASTM D 5423 (Type II ovens) and D 5374 and maintained at a temperature of 100 ±2°C (212 ±3.6°F) for 7 d (168 h) or 121 ±2°C (249.8 ±3.6°F) for 48 h at the manufacturer’s option. After removal from the oven, the specimens shall be allowed to cool to room temperature and then wound tightly, for six close turns, around a mandrel having a diameter no greater than that of the insulated conductor under test. The insulation shall be examined for cracks using a lens having magnification of 5X. The insulated conductor shall then be straightened, one side of the tube of insulation sliced off with a knife or razor-blade, and the conductor removed to permit examination of the inner surface of the insulation. There shall be no cracks on either the inside or the outside surface of the insulation.