Voltage Drop Calculator
Ensure your electrical circuits are safe and efficient. This calculator determines the voltage drop and power loss across a wire run based on NEC or IEC standards.
Calculation Results
Enter your circuit details to get the voltage drop.
What is Voltage Drop (and Why Does it Matter)?
Voltage drop describes the reduction in electrical potential energy (voltage) that occurs as electricity flows through a conductor. Every wire has some inherent resistance. As current flows through this resistance, a small amount of energy is lost, primarily as heat. This loss of energy results in a lower voltage at the end of the wire than at the source.
Properly calculating and managing voltage drop is one of the most important aspects of electrical circuit design for two key reasons:
- Efficiency: Excessive voltage drop means you are wasting energy. The power lost in the wire is converted into useless heat, which can lead to higher electricity bills.
- Safety and Performance: Many electrical devices are designed to operate within a specific voltage range. If the voltage drops too low, motors can overheat and burn out, lights can flicker or appear dim, and sensitive electronics can malfunction or be permanently damaged. In extreme cases, the heat generated can become a fire hazard.
How to Use the Voltage Drop Calculator
- Set Circuit Parameters: Choose the appropriate electrical code standard (NEC for North America, IEC for international), your wire material (Copper or Aluminum), and the circuit phase.
- Define Electrical Load: Enter your system's source voltage and the total current (in Amps) that your load will draw.
- Specify Conductor Details: Input the one-way length of the wire run and select the wire size you plan to use. The wire size options will automatically update based on the standard you selected.
- Calculate: Click the button to see a detailed analysis of your circuit's performance.
Understanding the Results
The National Electrical Code (NEC) generally recommends that the voltage drop for a circuit should not exceed **3%** for a branch circuit or **5%** for the total of a feeder and branch circuit. Our calculator will provide a "Pass" or "Warning" recommendation based on this 3% guideline, helping you decide if you need to use a thicker gauge wire to improve performance.
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