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The formula for calculating the cable size (or cross-sectional area) depends on several factors including the load current, the voltage drop allowed, the type of conductor material (usually copper or aluminum), the insulation type, and the ambient temperature. A common approach to sizing cables is to ensure that the cable can carry the expected load current without overheating and that the voltage drop along the cable does not exceed a specified limit.
: These affect the resistance of the conductor. formula for cable size calculation
[ A = \frac2 \cdot 100 \cdot 30 \cdot 1.68 \times 10^-81000 \cdot 6.9 \approx 14.6 mm^2 ] The formula for calculating the cable size (or
For a , the approximate voltage drop ($V_d$) is: [ A = \frac2 \cdot 100 \cdot 30 \cdot 1
) found in electrical standard tables (like the NEC or BS 7671): Is the room hot? Grouping ( Cgcap C sub g ): Are there many cables in one tray? Thermal Insulation ( Cicap C sub i ): Is the cable buried in glass wool? The Modified Formula:
Here is a comprehensive guide to the formulas for cable size calculation.
: Millivolt drop per ampere per meter (found in manufacturer data sheets). : The design current. : The length of the cable run in meters. If the calculated Vdcap V sub d