1. What is the 100 Amp Wire Sizing Calculation?

The 100 Amp Wire Sizing calculation determines the minimum cross-sectional area of a wire needed to carry 100 amps of current while maintaining an acceptable voltage drop over a specified length.

2. How Does the Calculator Work?

The calculator uses the wire sizing equation:

Where:

• \( A \) — Wire cross-sectional area (m²)
• \( L \) — Length of wire (meters)
• \( \rho \) — Resistivity of copper (1.68 × 10^-8 Ω·m)
• \( V_{drop} \) — Acceptable voltage drop (volts)
• 2 — Accounts for round-trip circuit length

Explanation: The equation calculates the minimum wire area needed to limit voltage drop when carrying 100 amps over a specified distance.

3. Importance of Proper Wire Sizing

Details: Correct wire sizing prevents excessive voltage drop, reduces heat generation, and ensures electrical safety and efficiency in 100 amp circuits.

4. Using the Calculator

Tips: Enter wire length in meters and desired maximum voltage drop in volts. Typical voltage drop limits are 3% of circuit voltage (e.g., 3.6V for 120V circuits).

5. Frequently Asked Questions (FAQ)

Q1: Why is copper resistivity used?
A: The calculator assumes copper conductors, which are most common. For aluminum, use ρ = 2.65 × 10^-8 Ω·m.

Q2: What's a typical voltage drop limit?
A: The National Electrical Code recommends ≤3% voltage drop for branch circuits and ≤5% for feeder and branch circuits combined.

Q3: How does wire length affect sizing?
A: Longer wire runs require larger conductors to maintain the same voltage drop due to increased resistance.

Q4: What about temperature effects?
A: This calculation uses standard temperature resistivity. For high-temperature environments, derating factors may apply.

Q5: How do I convert mm² to AWG?
A: Use standard AWG tables to match the calculated mm² to the nearest standard wire gauge that meets or exceeds the requirement.