As a general rule, the larger a wire's gauge, the higher its carrying capacity. However, as gauge increases, so too does the weight of the wire. If you're designing a towing wench or heavy-load pulley system, incorporating the weight of the wire itself is essential when calculating power output and required torque. Because its cross-sectional area is machined to such precision, calculating a wire's weight is as simple as multiplying the cross section by the length by the density of the material.
Determine the cross-sectional area of the wire's gauge. For a complete list of wire gauges and their respective cross-sectional areas, visit engineeringtoolbox.com. Note: from here on, this value will be referred to as the "metallic area."
Multiply the area by 0.01 to convert its units to square centimeters.
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Measure the complete diameter of the wire (including any plastic insulation) with a caliper. Note: take the measurement in centimeters.
Divide the measured diameter by 2, giving you the radius of the wire.
Square the radius and multiply the result by pi (i.e., 3.14). This is the complete cross-sectional area of the wire, including insulation. The area you determined in Step 1 only refers to the metal part of the wire.
Subtract the metallic area from the complete cross sectional area. This value represents the area of the plastic insulation. Note: if the wire has no insulation, the metallic area and complete cross-sectional area will be equal. Hence, the insulation's area will be equal to zero.
Determine the density of the metal used. For a complete list of popular wire metal densities, visit coolmagnetman.com.
Determine the specific gravity of the plastic insulation. For a complete list of common insulators and their specific gravities, visit dynalabcorp.com. If you are unsure which plastic was used, visit the manufacturer's website and view the product specifications for the wire.
Multiply the specific gravity by 1000 to determine the density of the insulation (in kilograms per cubic meter).
Multiply this plastic density by 0.001 to convert its units to grams per cubic centimeter.
Multiply the density of the metal (from Step 7) by the metallic area (from Step 2).
Multiply the density of the plastic (from Step 10) by the plastic area (from Step 6).
Add the result from Step 11 to the result from Step 12. This value is the mass per centimeter for the wire.
Multiply the mass per centimeter value from Step 13 by the planned length of the wire (in centimeters). This will give you the total mass of the wire, expressed in grams.
Multiply the wire's total mass by 0.0022 to convert it to pounds.