Calculation For Cable Size 【360p 480p】

Voltage drop (single-phase): [ V_d = \frac2 \times L \times I_b \times (R \cos\phi + X \sin\phi)1000 ] (3-phase): [ V_d = \frac\sqrt3 \times L \times I_b \times (R \cos\phi + X \sin\phi)1000 ] Where:

In real-world engineering, you must apply "Derating Factors" to the current before calculating. The environment affects the cable's ability to cool.

From cable table – 35 mm² Cu/PVC (ampacity ≈ 135 A) selected.

The purpose of this document is to outline the systematic methodology for determining the appropriate cross-sectional area (size) of an electrical cable. Proper cable sizing ensures:

Select a cable size whose tabulated current-carrying capacity (under reference conditions) ≥ rated ampacity needed.

Note: A $2.5mm^2$ cable would overheat and exceed the voltage drop limit.

For continuous loads: [ I_b = I_l \times \textDiversity Factor (if applicable) ] For motors or inductive loads, consider starting current and duty cycle.

If your load is 20A, but the cable is in a hot roof space with other cables, the derating factor might be 0.7. $$I_adjusted = \frac200.7 = 28.5 , Amps$$ You must calculate cable size based on 28.5A, not 20A.

35 mm² Cu/PVC (or upgrade to 50 mm² for future expansion).