Convert Square Pole (pole²) to Circular Mil (circ mil) instantly.
About these units
Square Pole (pole²)
A square pole is yet another equivalent to the square rod and square perch. The triple terminology reflects different regional dialects and occupational vocabularies within the British Isles. The persistence of three names for the same unit illustrates the decentralized nature of early measurement standards, where local custom often outweighed national regulation. Although modern metrication has replaced these units, they remain historically important when examining rural land divisions and genealogical land records.
Circular Mil (circ mil)
A circular mil is defined as the area of a circle with a diameter of exactly one mil. Because wires and cables have circular cross-sections, the circular mil has become a standard unit in electrical engineering for specifying conductor sizes. One circular mil simplifies calculations because area scales directly with the square of wire diameter without needing π in computations. For example, doubling a wire's diameter increases its circular-mil area fourfold. This makes circular mils extremely convenient for determining ampacity, resistance, and voltage drop in electrical conductors. Even though SI units are common elsewhere, the circular mil remains entrenched in North American electrical codes.