Voltage Drop Calculator
Calculate voltage loss & wire size
System Type
Circuit Parameters
Wire Specifications
Circuit Visualization
Voltage Drop vs Distance
Voltage Profile
Find Wire Size
Wire Size Options
| AWG Size | Area (mm²) | Resistance (Ω/km) | Voltage Drop | Status |
|---|
AWG Wire Reference Table
Standard American Wire Gauge (AWG) sizes with resistance values at 75°C
| AWG | Diameter (mm) | Area (mm²) | Copper (Ω/km) | Aluminum (Ω/km) | Ampacity (A) |
|---|---|---|---|---|---|
| 14 | 1.63 | 2.08 | 8.42 | 13.8 | 15 |
| 12 | 2.05 | 3.31 | 5.21 | 8.61 | 20 |
| 10 | 2.59 | 5.26 | 3.28 | 5.41 | 30 |
| 8 | 3.26 | 8.37 | 2.07 | 3.42 | 40 |
| 6 | 4.11 | 13.3 | 1.30 | 2.15 | 55 |
| 4 | 5.19 | 21.2 | 0.82 | 1.35 | 70 |
| 2 | 6.54 | 33.6 | 0.52 | 0.85 | 95 |
| 1 | 7.35 | 42.4 | 0.41 | 0.68 | 110 |
| 1/0 | 8.25 | 53.5 | 0.32 | 0.54 | 125 |
| 2/0 | 9.26 | 67.4 | 0.26 | 0.42 | 145 |
| 3/0 | 10.4 | 85.0 | 0.20 | 0.33 | 165 |
| 4/0 | 11.7 | 107 | 0.16 | 0.26 | 195 |
Wire Sizing Tips
NEC Guidelines
NEC recommends max 3% voltage drop for branch circuits and 5% for feeders
Temperature Matters
Wire resistance increases with temperature. Consider operating temperature
Ampacity Rating
Always choose wire with ampacity rating above your circuit's maximum current
Copper vs Aluminum
Copper has lower resistance but aluminum is lighter and less expensive
Understanding Voltage Drop
Voltage drop is the reduction in voltage in an electrical circuit between the source and load. It's caused by the resistance of the wire and is an important consideration in electrical design. Excessive voltage drop can lead to inefficient operation, overheating, and equipment damage.
Voltage Drop Formula
The voltage drop calculation depends on the type of electrical system:
- DC or Single-Phase AC: V_drop = 2 × I × L × R / 1000
- Three-Phase AC: V_drop = √3 × I × L × R / 1000
- Where: I = Current (A), L = Length (m), R = Resistance (Ω/km)
- Note: The factor of 2 accounts for both the supply and return conductors
NEC Voltage Drop Guidelines
The National Electrical Code (NEC) provides guidelines for acceptable voltage drop:
- Branch Circuits: Maximum 3% voltage drop recommended
- Feeders: Maximum 3% voltage drop recommended
- Total (Feeder + Branch): Maximum 5% voltage drop recommended
- Note: These are recommendations, not mandatory requirements
Factors Affecting Voltage Drop
Several factors influence voltage drop in a circuit:
- Wire Size: Larger wires have lower resistance and less voltage drop
- Wire Length: Longer runs have higher resistance and more voltage drop
- Current: Higher current causes more voltage drop
- Wire Material: Copper has lower resistance than aluminum
- Temperature: Higher temperatures increase resistance
Using This Calculator
Follow these steps:
- Step 1: Select your system type (DC, Single-Phase, or Three-Phase)
- Step 2: Enter source voltage and current
- Step 3: Enter wire length and select units
- Step 4: Select wire material and size
- Step 5: Click "Calculate" to see voltage drop
- Step 6: View recommendations if voltage drop is excessive
- Step 7: Use the Wire Size tab to find the proper wire gauge
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