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Free Tool

MCB Sizing Calculator

Work out the circuit breaker rating and curve type your load needs — enter your load in kW or amps, and we'll estimate the right MCB size and flag which ones we already have in stock.

Enter your load details

Standard Sudan supply: 230V single-phase / 400V three-phase, 50Hz.
Use 1.0 for purely resistive loads (heaters, incandescent lighting). 0.8 is a common default for mixed/motor loads.
Estimated Load Current
0.0 A
Recommended MCB
Suggested Curve
With Margin
Enter your load to see results.
Reference

Understanding MCB curve types

The "curve" determines how quickly the breaker trips under overload versus short-circuit conditions — matching it to your load type prevents nuisance tripping or under-protection.

B

Curve B

Trips at 3–5 × In

Most sensitive curve. Best for resistive loads with low inrush: lighting circuits, socket outlets, heaters, domestic distribution boards.

Order on request
C

Curve C

Trips at 5–10 × In

The general-purpose curve. Handles moderate inrush from small motors, fluorescent/LED banks, and mixed commercial or industrial circuits.

✓ In stock — C10, C16, C25, C32, C63
D

Curve D

Trips at 10–20 × In

Least sensitive curve. Needed for high inrush loads: large motors, transformers, welding equipment, X-ray and similar heavy machinery.

Order on request
This calculator is a general planning guide, not a substitute for professional design. Final circuit protection sizing must also account for cable cross-section and length (voltage drop), ambient temperature and grouping derating factors (per IEC 60364), discrimination/selectivity with upstream protection, and manufacturer-specific data. Always have your final electrical design reviewed by a qualified electrical engineer before installation. Almojahed's technical team is available to help — request a consultation.