Voltage Drop Calculator – Wire Gauge and Length
Calculate voltage drop for electrical wiring
Table of Contents
How to Use
- Enter the current in amperes
- Enter the wire length in feet (one-way distance)
- Select the wire gauge (AWG)
- Click calculate to see voltage drop and percentage drop
What is Voltage Drop?
Voltage drop is the reduction in voltage that occurs as electrical current flows through a wire's resistance. Longer wires, smaller wire gauges, and higher currents all increase voltage drop.
Excessive voltage drop can cause equipment malfunction, reduced efficiency, and safety hazards. The National Electrical Code (NEC) recommends keeping voltage drop below 3% for branch circuits and 5% total.
Proper Wire Sizing
- AWG (American Wire Gauge): Smaller numbers = larger wire
- Larger wires have less resistance and voltage drop
- Consider both current capacity and voltage drop
- Long wire runs may require larger gauge than ampacity alone suggests
Applications
- Electrical installation design
- Wire gauge selection
- Circuit troubleshooting
- Solar panel installations
- Low voltage lighting systems
- Automotive wiring
Frequently Asked Questions
- What is an acceptable voltage drop?
- The NEC recommends maximum 3% voltage drop for branch circuits (outlets) and 5% total from service panel to outlet. For critical equipment, aim for even lower voltage drop.
- How do I reduce voltage drop?
- Use larger wire gauge (smaller AWG number), shorten wire length, or reduce current. For long runs, consider increasing wire size by one or two gauges.
- Why does wire length matter?
- Longer wires have more resistance. The calculator accounts for round-trip distance (current flows out and back), so actual resistance is twice the one-way length.
Related Calculators
science
Acceleration Calculator
science
Alcohol Dilution Calculator – Solution Concentration