Amps to Cable Size Calculator
Use the amps to cable size calculator to quickly find the correct wire size for your electrical system. It helps you choose safe, efficient, and IEC-compliant cable sizes based on current load. Avoid overheating, voltage drop, and hazards by selecting the right cable every time.
Wire Size Selector
How to Use Amps to Cable Size Calculator
Follow these simple steps to use the amps to cable size calculator:
Step-by-Step Instructions
- Enter the load current (Amps).
- Select system type: Single-phase or Three-phase.
- Choose voltage level (e.g., 230V, 400V).
- Select conductor material: Copper or Aluminum.
- Choose installation method: In conduit, Buried, or Cable tray.
- Enter cable length (for voltage drop calculation).
- Apply derating factors: Ambient temperature and Grouping of cables.
- Click "Calculate".
The calculator will display the recommended cable size, adjusted current capacity, and estimated voltage drop.
How to Convert Amps to Cable Size (Step-by-Step)
You calculate cable size using current, installation conditions, and IEC standards.
Basic Formula (IEC Approach)
Cable size depends on Load current (I), Correction factors (Cf), and Current carrying capacity (Iz).
- Ca = Temperature derating factor
- Cg = Grouping factor
- Ci = Installation factor
Step-by-Step Example
Example: Load = 40 Amps, Installation = Conduit, Ambient Temp = 40°C, Grouping = 3 cables.
Step 1: Find derating factors (IEC tables): Ca = 0.87 (40°C), Cg = 0.70 (3 cables).
Step 2: Adjust current: Adjusted Current = 40 ÷ (0.87 × 0.70) ≈ 65.7 Amps.
Step 3: Select cable size: From IEC tables, 16 mm² copper is required (as 10 mm² handles ~57A).
Final Answer: Use 16 mm² copper cable.
Important Derating Factors (IEC Standards)
Always apply derating factors to ensure safety. Ignoring these factors can cause overheating and cable failure.
Common Derating Factors
- Temperature Factor (Ca): 25°C → 1.03 | 30°C → 1.00 | 40°C → 0.87 | 50°C → 0.71
- Grouping Factor (Cg): 1 cable → 1.00 | 2 cables → 0.80 | 3 cables → 0.70 | 4–6 cables → 0.65
- Installation Factor (Ci): Free air has higher capacity; conduit and buried installations reduce capacity.
Amps to Cable Size Conversion Chart (IEC - Copper)
Values follow IEC standards for copper conductors under normal conditions (30°C, single cable).
| Current (Amps) | Cable Size (mm²) | Typical Use |
|---|---|---|
| 10 A | 1.5 mm² | Lighting circuits |
| 16 A | 2.5 mm² | Socket outlets |
| 25 A | 4 mm² | Small appliances |
| 32 A | 6 mm² | Air conditioners |
| 40 A | 10 mm² | Medium loads |
| 63 A | 16 mm² | Distribution boards |
| 80 A | 25 mm² | Large equipment |
| 100 A | 35 mm² | Main supply lines |
| 125 A | 50 mm² | Industrial loads |
| 160 A | 70 mm² | Heavy-duty systems |
Note: Aluminum conductors require larger cross-sections than copper for the same load.
FAQs About Amps to Cable Size Calculator
An amps to cable size calculator helps you determine the correct cable size based on current, voltage, and installation conditions.
Correct cable sizing prevents overheating, voltage drop, and electrical hazards. It ensures safe and efficient operation.
Yes. Longer cables increase voltage drop. You may need a larger cable size to compensate for the loss of power over distance.
A smaller cable can overheat, damage insulation, and cause fire risks. Always follow IEC guidelines and safety standards.
Yes. IEC standards require derating for temperature, grouping, and installation conditions. Ignoring them leads to incorrect and unsafe sizing.
Copper offers higher conductivity and requires smaller sizes. Aluminum is cheaper but needs larger cross-sections and special connectors.