Calculation of Voltage Drop and Cable Size

Voltage Drop and Cable Size Formulas:

\[ V_d = \frac{2 \times I \times L \times R}{1000} \] \[ A = \frac{2 \times I \times L \times \rho}{V_d \times 1000} \]

Current (I):

Length (L):

Resistance (R):

Ω/km

Resistivity (ρ):

Ω·mm²/m

Voltage Drop (V_d):

Cross-Sectional Area (A):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Voltage Drop Calculation?

Voltage drop calculation determines the reduction in voltage in an electrical circuit between the source and load. It's essential for ensuring proper operation of electrical equipment and compliance with electrical codes.

2. How Does the Calculator Work?

The calculator uses the following formulas:

\[ V_d = \frac{2 \times I \times L \times R}{1000} \] \[ A = \frac{2 \times I \times L \times \rho}{V_d \times 1000} \]

Where:

\( V_d \) — Voltage drop (V)
\( I \) — Current (A)
\( L \) — Length of cable (m)
\( R \) — Resistance (Ω/km)
\( A \) — Cross-sectional area (mm²)
\( \rho \) — Resistivity (Ω·mm²/m)

Explanation: The first formula calculates voltage drop based on current, cable length, and resistance. The second formula calculates the required cable cross-sectional area to achieve a specific voltage drop.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop calculation ensures electrical devices receive adequate voltage for optimal performance, prevents energy waste, and maintains electrical safety standards.

4. Using the Calculator

Tips: Enter current in amperes, length in meters, resistance in ohms per kilometer, and resistivity in ohm·mm² per meter. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why is voltage drop important in electrical design?
A: Excessive voltage drop can cause equipment malfunction, reduced efficiency, and potential safety hazards in electrical systems.

Q2: What is an acceptable voltage drop percentage?
A: Most electrical codes recommend a maximum voltage drop of 3-5% for branch circuits and 1-2% for feeder circuits.

Q3: How does cable length affect voltage drop?
A: Voltage drop increases proportionally with cable length - longer cables have higher resistance and therefore greater voltage drop.

Q4: What factors influence cable resistance?
A: Cable resistance depends on material (copper/aluminum), cross-sectional area, temperature, and cable construction.

Q5: When should I be concerned about voltage drop?
A: Voltage drop should be calculated for all electrical installations, especially for long cable runs, high-current applications, and sensitive electronic equipment.