How To Calculate Cable Sizes Verified Info

Example: A 10 kW, 400V three-phase motor at 0.85 pf: ( I_b = 10000 / (1.732 \times 400 \times 0.85) = 16.98 A )

$$I = \frac15000\sqrt3 \times 415 \times 0.85 \approx 24.6 \text Amps$$ how to calculate cable sizes

Finally, you must ensure that in the event of a short circuit, the "fault current" is high enough to trip the breaker instantly. This involves checking the resistance of the cable (impedance). If the cable is too thin or too long, the breaker might not trip fast enough to prevent a fire. Summary Checklist Find ( Ibcap I sub b Pick a Breaker ( Incap I sub n Apply Correction Factors for heat/grouping. Pick a Cable Cross-Sectional Area ( mm2m m squared Check Voltage Drop limits. Ensure the Earth Path is safe. Example: A 10 kW, 400V three-phase motor at 0

[ I_z \geq I_b ]

: The voltage drop per ampere per meter (found in cable data sheets). : The length of the run in meters. If the calculated Vdcap V sub d Summary Checklist Find ( Ibcap I sub b