This tool helps you determine how much voltage is lost in an electrical circuit due to cable resistance, circuit length, and current draw. By entering your circuit details, you can quickly assess if your setup is within safe and efficient operating limits, and make adjustments if necessary. Follow the instructions below to begin. Please remember that this is simply a guide and you should always get advice from a trained professional and calculations should be confirmed with the cable manufacturers specifications.

Voltage Drop Calculator
Select cable cross-sectional area (mm²)
System nominal DC voltage (V)
Current draw (Amps)
One-way circuit length (m)
 
 
 

Understanding the Results

Voltage Drop Percentage and Voltage Drop in Volts

  • The voltage drop represents how much voltage is lost in the circuit due to wire resistance.
  • If the voltage drop percentage is too high (typically >4%), devices may not function properly or could be damaged.

Round-Trip Circuit Length

  • The circuit length accounts for the full "round trip" the current makes, from the power source to the load and back.
  • Longer circuits mean more resistance and higher voltage drop.

Cable Resistance

  • Cables with larger cross-sectional areas have lower resistance, reducing voltage drop.
  • Choosing the right cable size balances cost, performance, and safety.

What to Do If Voltage Drop Is Too High

  • Increase Cable Thickness: Use a cable with a larger cross-sectional area to lower resistance.
  • Shorten Circuit Length: Reduce the one-way distance between the power source and the load, if possible.
  • Reduce Current Demand: Use more efficient devices or spread the load across multiple circuits.