Wire Size for 15000W at 400V over 50m (4 mm² Copper) — Voltage Drop

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.

System & Voltage

Active Power (W)

One-way Cable Length (m)

Max Allowable Voltage Drop (%)

Conductor Material

Recommended Wire Size4 mm²

Exact Theoretical Area2.61 mm²

Line Current (Amps)15.2 A

Line Power Loss68 W

Voltage Drop & Conductor Cross-Section Formulas

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).

Direct Current (DC) & Single-Phase AC: S = (2 × L × I × ρ) / ΔU
Three-Phase Alternating Current (400V): S = (√3 × L × I × ρ × cos φ) / ΔU

Standard Copper Wire Sizes, Ampacity & Breaker Protection (NEC / IEC)

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

Wire Size for 15000W at 400V (50 Meters) → 4 mm²

Voltage Drop & Conductor Cross-Section Formulas

Standard Copper Wire Sizes, Ampacity & Breaker Protection (NEC / IEC)

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