Voltage drop calculator

  Select wire type:    
  Enter wire diameter size:  
  Enter wire length:  
  Select current type:    
  Enter voltage in volts: V  
  Enter current in amps: A  
     
  Voltage drop in volts: V  
  Percentage of voltage drop: %  
  Wire resistance: Ω  

Voltage drop describes how the supplied energy of a voltage source is reduced as electric current moves through the passive elements (elements that do not supply voltage) of an electrical circuit. Voltage drops across internal resistances of the source, across conductors, across contacts, and across connectors are undesired; supplied energy is lost (dissipated). Voltage drops across loads and across other active circuit elements are desired; supplied energy performs useful work.

For example, an electric space heater may have a resistance of ten ohms, and the wires which supply it may have a resistance of 0.2 ohms, about 2% of the total circuit resistance. This means that approximately 2% of the supplied voltage is lost in the wire itself. Excessive voltage drop may result in unsatisfactory operation of, and damage to, electrical and electronic equipment.

The local voltages along a long line decrease gradually from the source to the load

DC / single phase calculator:

Vdrop (V) = Iwire (A) × Rwire(Ω) = Iwire (A) × (2 × L(m) × Rwire (Ω/km) / 1000(m/km))

3 phase calculator:

Vdrop (V) = 0.866 × Iwire (A) × Rwire(Ω) = 0.866 × Iwire (A) × (2 × L(m) × Rwire (Ω/km) / 1000(m/km))

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