Voltage Drop Calculation Formula

Voltage Drop Equation:

\[ V_{drop} = \frac{2 \times L \times I \times \rho}{A} \]

Length (L):

meters

Current (I):

amps

Resistivity (ρ):

ohm m

Cross-sectional Area (A):

m²

Voltage Drop (V_drop):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Voltage Drop Formula?

The voltage drop formula calculates the decrease in voltage in an electrical circuit due to the resistance of the conductors. It's essential for proper circuit design and ensuring equipment receives adequate voltage.

2. How Does the Calculator Work?

The calculator uses the voltage drop equation:

\[ V_{drop} = \frac{2 \times L \times I \times \rho}{A} \]

Where:

\( V_{drop} \) — Voltage drop (volts)
\( L \) — Length of conductor (meters)
\( I \) — Current flowing through conductor (amps)
\( \rho \) — Resistivity of conductor material (ohm m)
\( A \) — Cross-sectional area of conductor (m²)

Explanation: The equation accounts for the resistance in both the supply and return paths (hence the factor of 2), the conductor's material properties, and its physical dimensions.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop calculation ensures electrical devices operate correctly, prevents excessive power loss, and maintains system efficiency. It's crucial for long cable runs and high-current applications.

4. Using the Calculator

Tips: Enter conductor length in meters, current in amps, resistivity in ohm meters, and cross-sectional area in square meters. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is an acceptable voltage drop?
A: Typically 3% for branch circuits and 5% for feeder circuits, but check local electrical codes for specific requirements.

Q2: How does conductor material affect voltage drop?
A: Different materials have different resistivities (e.g., copper has lower resistivity than aluminum for the same size).

Q3: Why is the factor of 2 included?
A: It accounts for both the "hot" and "neutral" (or positive and negative) conductors in a complete circuit.

Q4: How does temperature affect voltage drop?
A: Higher temperatures increase conductor resistance, which increases voltage drop. The calculator uses resistivity at standard temperature.

Q5: When should I be concerned about voltage drop?
A: For long cable runs, high current applications, or when powering sensitive equipment that requires stable voltage.