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A mil is one thousandth of an inch. A circular mil is the area of a circle one mil in diameter. That definition looks arbitrary until you see what it buys you. Why the unit exists Calculate the area of a round conductor in normal units and you need pi: Define your area unit as “the area of… Read More: Circular Mils Explained: cmil, kcmil and MCM »

Convert 12 AWG and you get 3.31 mm². Convert 4/0 and you get 107.2 mm². Neither is a cable you can buy. This is not a rounding problem. The two systems were built on different principles and they were never meant to agree. Two different design rules AWG is a geometric series. Diameters step by a fixed ratio… Read More: Why AWG and Metric Wire Sizes Never Line Up »

Metric conductors are divided into four classes. The class is not a quality grade — it describes the construction, and it changes the diameter, the flexibility, and the resistance the conductor has to meet. The four classes Class Construction Intended for 1 Solid Fixed installations 2 Stranded Fixed installations 5 Flexible Flexible cables and cords 6 More flexible… Read More: Conductor Classes 1, 2, 5 and 6 Explained »

Ask what 12 AWG is in millimetres and you can get two correct answers: Both are right. They describe different things, and picking the wrong one causes real problems. Which number for which job Use the diameter (mm) when you are dealing with physical hardware. Ferrules, cable glands, terminal clamp ranges, conduit fill, drill sizes, and whether a… Read More: AWG Diameter vs Cross-Section: Two Different Answers »

American Wire Gauge is not a measurement system. It is a geometric series, and once you know the two numbers it is built on, you can calculate any gauge without a table. Two fixed points and 39 steps The whole system is pinned at two diameters: Everything between is spaced by a constant ratio. There are 39 steps… Read More: American Wire Gauge: How AWG Sizes Are Derived »