Length Using Resistance (1-Phase 2-Wire US) Calculator

Formula Used:

\[ L = \frac{R \times A}{\rho} \]

Length of Underground AC Wire (L):

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1. What is the Length Using Resistance Formula?

The Length Using Resistance formula calculates the length of an underground AC wire based on its resistance, cross-sectional area, and material resistivity. This is particularly useful in 1-Phase 2-Wire US electrical systems for determining wire length requirements.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ L = \frac{R \times A}{\rho} \]

Where:

\( L \) — Length of Underground AC Wire (meters)
\( R \) — Resistance Underground AC (ohms)
\( A \) — Area of Underground AC Wire (square meters)
\( \rho \) — Resistivity of the material (ohm-meters)

Explanation: The formula derives from the fundamental relationship between resistance, resistivity, length, and cross-sectional area of a conductor.

3. Importance of Length Calculation

Details: Accurate length calculation is crucial for proper electrical system design, voltage drop estimation, power loss calculation, and ensuring compliance with electrical codes and standards.

4. Using the Calculator

Tips: Enter resistance in ohms, area in square meters, and resistivity in ohm-meters. All values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: Why is resistivity important in this calculation?
A: Resistivity is a material property that determines how strongly a material opposes electric current flow, directly affecting the resistance for a given length and cross-section.

Q2: What are typical resistivity values for common conductor materials?
A: Copper: 1.68×10⁻⁸ Ω·m, Aluminum: 2.82×10⁻⁸ Ω·m, Silver: 1.59×10⁻⁸ Ω·m at 20°C.

Q3: How does temperature affect the calculation?
A: Resistivity changes with temperature, so the calculation should use resistivity values at the expected operating temperature for accurate results.

Q4: Can this formula be used for AC and DC systems?
A: Yes, the basic resistance formula applies to both AC and DC systems, though AC systems may require additional considerations for skin effect and proximity effect.

Q5: What are the limitations of this calculation?
A: This calculation assumes uniform material properties, constant cross-section, and doesn't account for temperature variations along the wire length.