What does "MCM" refer to, commonly found in older electrical resources?

"MCM" stands for "thousands of circular mils," which is a unit of measure used to express the cross-sectional area of electrical conductors, particularly in larger gauge wires. When you see "MCM" in older electrical resources, it is essentially indicating the size of conductors, especially in the context of large cables used in industrial applications.

The designation "kcmil" is synonymous with MCM and indicates the same measurement unit—specifically, it represents the area in thousands of circular mils. This unit is crucial in electrical wiring, as it allows for standardization and easy comparison of wire sizes based on their ability to carry current safely without overheating.

The other terms do not represent the same measurement. "Square mm" is a metric unit of area, "AWG" refers to American Wire Gauge, which is a standardized wire gauge system used primarily in the United States for smaller conductors, and "kV" indicates kilovolts, a measure of electrical voltage. Thus, understanding that MCM is equivalent to kcmil clarifies the choice and the significance of MCM in the context of wiring and conductor sizing.