Home
Back
Voltage Drop Formula:
| From: | To: |
The Voltage Drop Calculation Formula per NEC (National Electrical Code) estimates the voltage drop in an electrical circuit based on current, resistance, and length factor. It helps ensure proper voltage levels at the load end of electrical installations.
The calculator uses the voltage drop formula:
Where:
Explanation: The formula calculates the voltage drop across a conductor by multiplying the current flowing through it by the resistance and the appropriate length factor as specified in the NEC.
Details: Accurate voltage drop calculation is crucial for designing electrical systems that deliver adequate voltage to equipment, preventing performance issues and ensuring compliance with NEC standards.
Tips: Enter current in amperes, resistance in ohms, and length factor as per NEC guidelines. All values must be valid positive numbers.
Q1: Why is voltage drop calculation important?
A: Voltage drop calculation ensures that electrical equipment receives sufficient voltage to operate properly and prevents excessive power loss in conductors.
Q2: What are acceptable voltage drop limits per NEC?
A: NEC recommends that voltage drop should not exceed 3% for branch circuits and 5% for feeder and branch circuits combined.
Q3: How is length factor determined?
A: Length factor is based on conductor length, size, and material, as specified in NEC tables and formulas for different installation conditions.
Q4: Does this calculation apply to AC and DC circuits?
A: While the basic formula applies to both, AC circuits may require additional considerations for impedance and power factor.
Q5: When should voltage drop be calculated?
A: Voltage drop should be calculated during the design phase of electrical installations and when verifying existing installations for compliance.