Always consult your local electrical codes (NEC in the US, IEC/BS in the UK) before performing any wiring, as specific regulations may override general formulas.
Real-world conditions change how much heat a cable can dissipate. When selecting your final size from a table, you must apply correction factors ( Is the cable in a hot attic? Grouping: Are there ten other cables bundled next to it? Insulation: Is the cable buried in thermal insulation? The formula for the "Effective Current" ( Itcap I sub t ) becomes: how to find the cable size formula
While the current calculation tells you the minimum capacity, the is most often used to mathematically "solve" for the cross-sectional area of the cable conductor. This ensures the equipment at the end of the wire receives sufficient voltage. Always consult your local electrical codes (NEC in
As electricity travels down a wire, it loses energy due to resistance. If the cable is too long, the voltage at the end might be too low to run your device. Step 1: Calculate the Load Current ( Grouping: Are there ten other cables bundled next to it