Calculate electrical wire size in mm² and AWG for 12V, 24V, 120V, 230V and 400V based on power, length and voltage drop under NEC Table 310.16 and IEC 60364.
Regulatory Reference (USA & International): Under NFPA 70 (NEC Art. 210.19) and IEC 60364-5-52, maximum recommended voltage drop is 3% for branch circuits and 5% combined feeder + branch. Ampacity must comply with NEC Table 310.16 (75°C / 90°C copper).
| Wire Size (mm²) | Max Current PVC (A) | Typical Breaker (MCB) | Typical Residential / Solar Application |
|---|---|---|---|
| 1.5 mm² | 15 A | 10 A | Lighting circuits (C1) & signaling |
| 2.5 mm² | 21 A | 16 A | General power outlets (C2) & kitchen/bath (C5) |
| 4.0 mm² | 27 A | 20 A | Washing machine, dishwasher & water heater |
| 6.0 mm² | 36 A | 25 A | Electric stove, oven & medium solar inverters |
| 10.0 mm² | 50 A | 40 A | Main sub-feeders & EV charging station (Wallbox) |
| 16.0 mm² | 66 A | 50 A / 63 A | High-power main feeders & 24V/48V battery banks |
83.3 A | PIA/MCB: 80A
125.0 A | PIA/MCB: 125A
166.7 A | PIA/MCB: 200A
125.0 A | PIA/MCB: 125A
104.2 A | PIA/MCB: 125A
16.0 A | PIA/MCB: 16A
26.3 A | PIA/MCB: 20A
33.9 A | PIA/MCB: 25A / 32A
16.7 A | PIA/MCB: 16A
22.8 A | PIA/MCB: 20A
33.4 A | PIA/MCB: 25A / 32A
41.7 A | PIA/MCB: 80A
For DC and single-phase AC circuits, cross-sectional area S (mm²) = (2 × Length × Current × ρ) / Voltage Drop (V). Always verify that conductor ampacity meets NFPA 70 (NEC Table 310.16) or IEC 60364.
Under NEC and IEC standards, the recommended maximum voltage drop is 3% for branch circuits and 5% total for combined feeder and branch circuits.