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Circular Mil Formula:
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A circular mil is a unit of area used especially for denoting the cross-sectional size of a wire or cable. One circular mil is the area of a circle with a diameter of one mil (one thousandth of an inch).
The calculator uses the circular mil formula:
Where:
Explanation: The area in circular mils is simply the square of the diameter in mils. This formula works because the area of a circle in circular mils is proportional to the square of its diameter.
Details: Calculating circular mils is essential in electrical engineering for determining wire size, current carrying capacity, and voltage drop in electrical circuits. It's a standard measurement in the wire and cable industry.
Tips: Enter the wire diameter in mils (thousandths of an inch). For example, a wire with 0.064 inch diameter would be entered as 64 mils.
Q1: What is the difference between circular mils and square mils?
A: A circular mil is a unit of area equal to the area of a circle with a diameter of one mil, while a square mil is the area of a square with sides of one mil. 1 circular mil = π/4 square mils ≈ 0.7854 square mils.
Q2: Why use circular mils instead of square inches?
A: Circular mils provide a more convenient unit for wire cross-sectional area since wire diameters are typically measured in mils, and the calculation simplifies to d².
Q3: How do I convert circular mils to square inches?
A: To convert circular mils to square inches, multiply by π/4,000,000 (since 1 circular mil = π/4 × 10⁻⁶ square inches).
Q4: What is the relationship between circular mils and American Wire Gauge (AWG)?
A: AWG is a standardized wire gauge system. For each 6 gauge decrease, the wire diameter doubles, and the circular mil area quadruples.
Q5: How does circular mil area affect current carrying capacity?
A: Generally, a larger circular mil area allows a wire to carry more current, though the exact relationship depends on factors like insulation type, ambient temperature, and installation method.