ASTM B8 standard is a specification that covers bare concentric-lay-stranded conductors made from round copper wires, either uncoated or coated with tin, lead, or lead alloy for general use for electrical purposes. These conductors are constructed with a central core surrounded by one or more layers of helically laid wires. The standard classifies the conductors into five classes: Class AA, Class A, Class B, Class C, and Class D. Each class has different requirements for sizes, number of wires, diameter of wires, minimum distance between joints, diameters, areas, mass and electrical resistance.
ASTM B8 standard provides guidance for manufacturers and users of copper conductors on how to select the appropriate class of conductor based on the intended use. For example,
– Class AA conductors are usually used in overhead lines where high strength and low flexibility are required.
– Class A conductors are suitable for covering with weather-resistant materials or for bare applications where more flexibility than Class AA is needed.
– Class B conductors are designed for insulating with various materials or for more flexible applications than Class A.
– Class C and D conductors offer even more flexibility than Class B and are used where extreme bending is required.