UL-83:2014 pdf free download – STANDARD FOR SAFETY Thermoplastic-Insulated Wires and Cables.
4.1.5.2.4 Assembly of strands
A 19-wire combination round-wire unilay stranded conductor shall be round and shall consist of a straight central wire, an inner layer of six wires of the same diameter as the central wire, and an outer layer consisting of six wires with the same diameter as the central wire alternated with six wires with a diameter of 0.732 times the diameter of the central wire. No particular assembly of the individual wires of any other stranded conductor shall be required. However, simple bunching (untwisted strands) shall not be used. The length of lay of the strands in a bunch-stranded conductor twisted as a single bunch shall not be greater than as indicated in Table 3. The direction of lay of the strands in a bunch-stranded conductor shall be left-hand.
4.1.5.2.5 Length and direction of lay
Every stranded conductor other than a compact-stranded conductor or a bunch-stranded conductor twisted as a single bunch shall comply with the following:
a) The direction of lay of the strands, members, or ropes in a 13.3 — 1010 mm2 (6 AWG —2000 kcmil) conductor, other than a combination unilay or a compressed unilay or compressed
unidirectional lay conductor, shall be reversed in successive layers. Rope-lay conductors with bunch-stranded or concentric-stranded members shall be either unidirectional or reversed. All unidirectional lays and the outer layer of reversed lays shall be in the left-hand direction.
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 the member. 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 copper or aluminum 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 conductor consisting of fewer than 37 strands shall be 8 — 16 times the outside
diameter of the 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.
4.1.6 Diameter and cross-sectional area
4.1.6.1 The nominal diameters of solid and stranded conductors are shown in Tables 4 – 9. The minimum diameter for stranded conductors is 98 percent of the nominal. The maximum diameter is 101 percent of the nominal. The diameter shall be determined in accordance with the test, Conductor diameter, in UL 2556, CSA C22.2 No. 2556, or NMX-J-1 29-ANCE.