Calculate Size Of Cable -

Use standard electrical formulas based on load type.

Typically, a voltage drop of 2-3% is acceptable. calculate size of cable

In modern buildings with computers and LED lighting, 3rd harmonics are high. Use standard electrical formulas based on load type

If you only know the wattage of your device, use the Power Law to find the Amps: Three Phase: (Where is Power in Watts and PFcap P cap F is Power Factor, usually 0.8 to 1.0). Step B: Select a Preliminary Cable Size calculate size of cable

Find the total derating factor ($C_total = C_a \times C_g \times C_i \dots$). Calculate minimum tabulated ampacity: $I_z = I_n / C_total$. Go to standard tables (e.g., IEC 60364-5-52 or NEC Table 310.16) and find a cable size with a rating $\geq$ calculated $I_z$.