Calculate cable size based on current capacity and voltage drop requirements.
Enter current and click Calculate
Correct cable sizing is critical for electrical safety and system performance. Undersized cables cause excessive heat, voltage drop, energy loss, and fire hazards. Oversized cables waste money and complicate installation. This calculator helps find the optimal balance based on NEC and IEC standards.
1. Current Carrying Capacity (Ampacity): The cable must safely carry the load current without overheating. Factors include conductor material, insulation type, installation method, ambient temperature, and grouping.
2. Voltage Drop: The cable must maintain voltage within acceptable limits (typically 3-5% for branch circuits). Longer runs and higher currents require larger conductors to minimize voltage drop.
| Size (mm²) | AWG Equiv. | Typical Ampacity | Common Application |
|---|---|---|---|
| 1.5 | 16 AWG | 15A | Lighting circuits |
| 2.5 | 14 AWG | 20A | General power outlets |
| 4 | 12 AWG | 27A | Heavy appliances |
| 6 | 10 AWG | 36A | Sub-panels, AC units |
| 10 | 8 AWG | 50A | Large motors |
| 16 | 6 AWG | 68A | Main feeders |
Temperature: Ampacity decreases at higher ambient temperatures. Apply correction factors from NEC Table 310.15(B)(2).
Bundling: Multiple cables in conduit or trays generate heat. Apply grouping factors from NEC Table 310.15(B)(3).
Insulation Type: Higher-rated insulation (THHN, XHHW) allows more current than standard (TW, THW).
Single Phase: VD = (2 × L × I × R) / 1000
Three Phase: VD = (√3 × L × I × R) / 1000
Where: L = length (m), I = current (A), R = resistance (mΩ/m)