ASTM B787/B787M-04(2020) pdf free download.Standard Specification for 19 Wire Combination Unilay-Stranded Copper Conductors for Subsequent Insulation.
ASTM B787/B787M-04(2020) covers bare combination unilay-stranded conductors made from round copper wires, either uncoated or coated with tin or lead alloy for insulated conductors for electrical purposes. These conductors shall be constructed with a central core wire surrounded by two layers of helically laid wires, resulting in an outer diameter equal to the compressed-stranded equivalent conductor.
For the purpose of calculating masses, cross sections, and so forth, the density of the copper shall be taken as 8.89 g/cm3 (0.32117 lb/in.3) at 20°C.
The mass and electrical resistance of a unit length of stranded conductor are a function of the length of lay. The approximate mass and electrical resistance may be determined using the standard increment of 2 %. When greater accuracy is desired, the increment based on the specific lay of the conductor may be calculated.
The manufacturer shall afford the inspector representing the purchaser all reasonable manufacturer’s facilities to satisfy him that the material is being furnished in accordance with this specification.
The net weight, length (or lengths and number of lengths, if more than one length is included in the package), size, kind of conductor, purchase order number, and any other marks required by the purchase order shall be marked on a tag attached to the end of the conductor inside of the package. The same information, together with the manufacturer’s serial number (if any) and all shipping marks required by the purchaser, shall appear on the outside of each package.