ASTM B786/B786M-08 (R2018) PDF Download

The ASTM B786/B786M-08 (R2018) standard specifies the requirements for bare combination unilay-stranded conductors made from round wires of aluminum 1350 and 8000 series aluminum alloys. These conductors are intended for use in insulated conductors for electrical purposes.

The standard permits the use of aluminum 1350 wires in various tempers, including -H19, -H16 or -H26, -H14 or -H24, and -H142 or -H242, as well as 8000 series aluminum alloy wires in tempers "0" and H1X or H2X. The conductors are constructed with a central core wire surrounded by two layers of helically laid wires, resulting in an outer diameter equivalent to compressed-stranded conductors.

The individual wires composing the conductor may be joined together using electric-butt welds, cold pressure welds, or electric-butt cold-upset welds. The standard specifies mechanical (tension) and electrical tests to be performed on the wires, both annealed and not annealed after stranding. The mass and electrical resistance of a unit length of stranded conductor are determined as a function of the length of lay.

The conductors must meet requirements for breaking strength, tensile strength, and bending strength. It is important to note that the standard does not utilize the normal conductor classification (Class AA, A, B, C) but instead uses the descriptive term "combination unilay-stranded" due to the intended use of these conductors for subsequent insulation. The standard also provides additional notes regarding the designations of aluminum and temper in accordance with ANSI Standard H35.1 and the Unified Numbering System.