A square rod is a unit of area measurement that is now considered obsolete and not commonly used in modern times. It was historically used in some English-speaking countries, including the United States and the United Kingdom, as part of the older system of land measurement.
One square rod is equal to an area of 1/160th of an acre or 1/4,840th of a square yard. In terms of square meters, one square rod is approximately equal to 25.29285264 square meters (m²).
The square rod was often used in land surveys and property descriptions in the past, but it has been largely replaced by more standardized systems of measurement. In modern times, square meters and square feet are the more commonly used units for measuring land area.
A circular mil (often abbreviated as cmil or kcmil) is a unit of area used primarily in the United States for measuring the cross-sectional area of a round wire or cable. It is a convenient unit for specifying the size of electrical conductors.
One circular mil is equal to the area of a circle with a diameter of one mil (1/1000th of an inch) or approximately 0.000000506707 square inches (in²). In metric units, one circular mil is approximately equal to 0.000001273 square millimeters (mm²).
Circular mils are commonly used in the American Wire Gauge (AWG) system to specify wire sizes. The AWG system assigns a unique number to each wire size, and this number is related to the wire's cross-sectional area in circular mils. For example, a larger AWG number corresponds to a smaller wire size with fewer circular mils, while a smaller AWG number corresponds to a larger wire size with more circular mils. This system allows for easy reference and selection of wire sizes for various electrical applications.