Wire Gauging Equipment, Optical-Type

With optical gauging instruments, wire is checked by use of photo­electric cells in different ways, the simplest method employing a measuring cell and a reference cell. For very fine wires, the diameter is often measured by weighing a specific length of the wire, which provides only the average cross section. More accurate measurement is obtained by measuring the electric resistivity of the wire or by measuring the greatly enlarged shadow area. See Cable Diameter Gauging entries.