Voltage Drop Calculator by Southwire

Voltage Drop Formula:

\[ VD = \frac{2 \times I \times L \times R}{1000} \]

Voltage Drop (VD):

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1. What is a Voltage Drop Calculator?

Definition: This calculator estimates the voltage drop in an electrical circuit based on current, wire length, and resistance.

Purpose: It helps electricians and engineers ensure proper voltage levels in electrical installations.

2. How Does the Calculator Work?

The calculator uses the Southwire voltage drop formula:

\[ VD = \frac{2 \times I \times L \times R}{1000} \]

Where:

\( VD \) — Voltage drop (volts)
\( I \) — Current (amperes)
\( L \) — Length of wire (feet)
\( R \) — Resistance (ohms per 1000 feet)

Explanation: The formula accounts for the round-trip distance (hence the 2) of the electrical current through the conductor.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop estimation ensures electrical devices receive adequate voltage and prevents performance issues or safety hazards.

4. Using the Calculator

Tips: Enter the current in amps, wire length in feet, and conductor resistance in ohms per 1000 feet. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is the length multiplied by 2?
A: The factor of 2 accounts for the round-trip path of the current (out to the load and back).

Q2: Where can I find resistance values?
A: Consult wire manufacturer specifications or NEC tables for resistance values of different wire gauges.

Q3: What's an acceptable voltage drop?
A: Typically 3% for branch circuits and 5% for feeder circuits, but check local electrical codes.

Q4: Does this work for DC circuits?
A: Yes, the formula works for both AC and DC single-phase circuits.

Q5: How does temperature affect the calculation?
A: Higher temperatures increase resistance. For precise calculations, use resistance values at operating temperature.