DC Wire Size Calculator
Calculate optimal DC wire size based on current, voltage, distance, and allowable voltage drop
Calculate DC Wire Size
Common values: 12V, 24V, 48V, 120V, 240V
Current load in amperes (A)
Distance from source to load (one-way)
Typically 3% for DC circuits
Resistivity at 20°C
Maximum wire operating temperature
Example Calculation
200A DC System at 120V
System: 120V DC source with 200A load
Distance: 50m one-way (copper wire)
Allowable drop: 3% (3.6V)
Operating temperature: 50°C
Calculation Steps
A = (2 × I × ρ × D) / V
A = (2 × 200A × 1.68×10⁻⁸Ω⋅m × 50m) / 3.6V
A = 0.000336 / 3.6 = 0.0000933 m²
Result: 93.3 mm² ≈ 4/0 AWG wire
Common DC Systems
Automotive
Cars, boats, RVs
3% voltage drop typical
Solar Systems
Small off-grid systems
2-3% voltage drop
Telecom
Data centers, telecom
1-2% voltage drop
AWG Wire Sizes
Understanding DC Wire Size Calculations
Why Wire Size Matters
Proper DC wire sizing is crucial for electrical safety, system efficiency, and preventing voltage drops that can damage equipment. Undersized wires can overheat, while oversized wires increase costs unnecessarily.
Key Factors
- •Current (I): Higher current requires larger wire
- •Distance (D): Longer runs need bigger wires
- •Voltage Drop: Lower percentage = larger wire
- •Material: Copper has lower resistance than aluminum
DC Wire Size Formula
A = (2 × I × ρ × D) / V
Where V = (% drop × Source Voltage) / 100
- A: Cross-sectional area (m²)
- I: Current (amperes)
- ρ: Resistivity (Ω⋅m)
- D: One-way distance (meters)
- V: Allowable voltage drop (volts)
- 2: Factor for return path
Safety Note: Always consult local electrical codes and a qualified electrician for installations.