UL-1690:2011 pdf free download – Underwriters Laboratories Inc. Standard for Safety Data-Processing Cable.
b) For a bunch-stranded member of a rope-lay-stranded conductor in which the members are formed into rope-stranded components that are then cabled into the final conductor, the length of lay of the individual members within each component shall not be more than 30 times the
outside diameter of one of those members.
c) For a concentric-stranded member of a rope lay-stranded conductor, the length of lay of the individual strands in a member shall be 8 — 16 times the outside diameter of that layer. The
direction of lay of the strands in each member shall be reversed in successive layers of the member.
d) The length of lay of the strands in both layers of a 19-wire combination round-wire unilaystranded conductor shall be 8 — 16 times the outside diameter of the completed conductor.
Otherwise, the length of lay of the strands in every layer of a concentric-lay-stranded or
compressed-stranded conductor consisting of fewer than 37 strands shall be 8 — 16 times the outside diameter of that conductor.
e) The length of lay of the strands in the outer two layers of a concentric-lay-stranded
conductor consisting of 37 or more strands shall be 8 — 16 times the outside diameter of the conductor.
f) The length of lay of the members or ropes in the outer layer of a rope-lay-stranded conductor shall be 8 — 16 times the outside diameter of that layer.
13 Insulation
13.1 Material and Application
13.1.1 Each conductor shall be insulated for its entire length with one or more of the insulation materials indicated in Table 13.1 or referenced in note a to Table 13.1. The insulation shall be solid or, in the cases indicated in the second column of Table 13.1, may be expanded or 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 13.1 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. 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. The use of foamed or expanded insulation or an air-gap construction is limited to Type DP-3 series cables.
13.1.2 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 Long-Term Aging, Section 481 of UL
1581:
a) Material generically different from any insulation or jacket material that is named in Table 13.1 or 16.1 (new material).
b) Material that is named in Table 13.1 or 16.1 yet does not comply with the short-term tests specified for the material.
The temperature rating of materials (a) and (b) shall be as required for the specific data-processing cable type. The thicknesses of insulation and/or jacket using materials (a) and/or (b) shall be as required for the 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 13.1 or 16.1 for the required temperature rating. The investigation shall include tests such as crushing, impact, abrasion, deformation, heat shock, insulation resistance, and dielectric voltage-withstand.