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Wire Circular Mils Formula:
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Circular mils (CM) 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 Mils formula:
Where:
Explanation: The formula calculates the cross-sectional area of a wire in circular mils by taking the diameter in inches, converting it to mils, and then squaring the result.
Details: Calculating circular mils is essential for determining the current-carrying capacity of wires, voltage drop calculations, and proper wire sizing for electrical applications.
Tips: Enter the wire diameter in inches. The value must be greater than 0. For accurate results, measure the diameter precisely using appropriate measuring tools.
Q1: Why use circular mils instead of square inches?
A: Circular mils provide a more convenient unit for wire cross-sectional area as it eliminates the need for π in calculations and is widely used in electrical engineering standards.
Q2: What is the relationship between circular mils and American Wire Gauge (AWG)?
A: AWG is a standardized wire gauge system where larger numbers represent smaller wires. There are formulas and tables to convert between AWG and circular mils.
Q3: How does circular mils relate to current carrying capacity?
A: Generally, a larger circular mils value indicates a thicker wire that can carry more current. Specific current ratings depend on the wire material, insulation type, and installation conditions.
Q4: Can I use this calculator for stranded wire?
A: For stranded wire, you would typically use the overall diameter of the stranded bundle, not individual strand diameters.
Q5: What are common circular mils values for household wiring?
A: Common household wiring sizes range from about 1,620 CM (14 AWG) to 10,380 CM (8 AWG) for branch circuits, with larger sizes for service entrances.