Cable Sizing Calculator
Determine appropriate cable sizes based on load current, voltage drop limits, and installation conditions. Includes IEC derating factors for temperature, grouping, and installation methods.
Enter load parameters and click Calculate to see cable sizing results
Notes:
- Calculations based on IEC 60364 / BS 7671 standards
- Maximum voltage drop typically 3% for final circuits, 5% total
- XLPE insulation allows higher operating temperature
- Always verify with local electrical codes and regulations
- Consider future load growth when selecting cable sizes
DISCLAIMER
This calculator provides ESTIMATES for preliminary planning purposes. Results are based on standard assumptions and may not reflect your specific project conditions.
By using this tool, you acknowledge that:
1. All calculations are approximate and based on typical industry standards and assumptions.
About This Calculator
The Cable Sizing Calculator helps electrical engineers and MEP contractors determine the correct cable cross-section for power distribution systems across the UAE and Gulf. Calculate required cable sizes based on load current, voltage drop limits, cable length, and installation conditions. Applies IEC/BS derating factors for ambient temperature, cable grouping, and installation methods commonly used in Gulf construction.
When to Use This Calculator
- Designing electrical distribution systems for buildings
- Sizing main feeders and sub-main cables
- Checking voltage drop compliance for long cable runs
- Applying derating factors for Gulf climate conditions
- Verifying cable specifications for tender submissions
How to Use This Calculator
Enter Load Details
Input load current (A), voltage (V), and power factor for the circuit.
Specify Cable Route
Enter cable length and select installation method (tray, conduit, direct burial, etc.).
Set Derating Factors
Apply factors for ambient temperature, cable grouping, and installation conditions.
Check Voltage Drop
Verify voltage drop is within acceptable limits (typically 3-5% for final circuits).
Review Cable Size
Get recommended cable cross-section (mm²) with current-carrying capacity verification.
Typical Scenarios in UAE & Gulf Projects
An MEP contractor needs to size the main feeder cable from transformer to main distribution board (150m run, 800A load). The calculator determines 3×300mm² cables per phase with voltage drop of 2.1%, meeting the 3% limit for main feeders.
A factory requires cable sizing for 45°C ambient temperature with cables in outdoor trenches. Derating factors reduce standard capacity by 25%, requiring upsizing from 95mm² to 150mm² for a 200A motor feeder.
Calculation Methodology
How Cable Sizing Works
Cable sizing ensures the selected conductor can safely carry the design current without overheating or exceeding voltage drop limits. The fundamental requirement is Iz ≥ Ib ÷ (Ca × Cg × Ci), where Iz is the cable's tabulated current rating, Ib is the design current, and Ca, Cg, Ci are derating factors for ambient temperature, cable grouping, and installation method respectively. The calculator selects the smallest standard cable size (from 1.5 mm² to 300 mm²) whose derated capacity meets or exceeds the design current.
Voltage Drop Calculation
After selecting a cable for current capacity, the voltage drop must be verified. The formula is: Vd(%) = (mV/A/m × Ib × L) ÷ (1000 × V) × 100, where mV/A/m is the cable's voltage drop per ampere per metre (from IEC tables), Ib is the design current in amps, L is the one-way cable length in metres, and V is the system voltage. Per DEWA and ADDC regulations, voltage drop must not exceed 3% for main feeders, 2.5% for sub-mains, and 5% total from transformer to final outlet. If the drop exceeds limits, the calculator automatically upsizes the cable.
Understanding Derating Factors for Gulf Conditions
Standard cable ratings assume 30°C ambient temperature, a single circuit, and open installation. Gulf construction rarely matches these ideal conditions. The ambient temperature factor (Ca) reduces capacity for the 40–50°C temperatures common in UAE — for example, a PVC cable at 45°C is derated to 79% of its standard rating. The grouping factor (Cg) accounts for reduced heat dissipation when multiple cables share a tray or conduit — three grouped cables retain only 70% of individual capacity. The installation method factor (Ci) reflects whether the cable is clipped to a surface (factor 1.0), in conduit (0.87), or buried in a duct (0.80). All three factors multiply together to determine the effective current-carrying capacity.
Frequently Asked Questions
Take Your Calculations Further
This calculator reflects the logic built into Arkan's construction management platform.
Last Updated: January 2026
Standards Reference: Calculations based on IEC 60364 and BS 7671 (IET Wiring Regulations)