1. What is the Southwire Cable Pull Equation?

The Southwire Cable Pull Equation calculates the output tension when pulling cable through conduits with bends. It accounts for friction and bend angles to determine the force required for cable installation.

2. How Does the Calculator Work?

The calculator uses the Southwire equation:

Where:

• \( T_{out} \) — Output tension (lb or N)
• \( T_{in} \) — Input tension (lb or N)
• \( \mu \) — Friction coefficient (dimensionless)
• \( \theta \) — Bend angle (radians)

Explanation: The equation calculates how tension increases exponentially as cable passes through bends due to friction.

3. Importance of Cable Pull Calculation

Details: Accurate tension calculation is crucial for preventing cable damage, ensuring proper installation, and determining appropriate pulling equipment and techniques.

4. Using the Calculator

Tips: Enter input tension in lb or N, friction coefficient (typically 0.1-0.5 for common materials), and bend angle in radians. All values must be valid (tension > 0, μ ≥ 0, θ ≥ 0).

5. Frequently Asked Questions (FAQ)

Q1: What are typical friction coefficient values?
A: For common installations: 0.1-0.2 for lubricated PVC, 0.3-0.5 for dry conduits, depending on cable and conduit materials.

Q2: How do I convert degrees to radians?
A: Multiply degrees by π/180. For example: 90° = 90 × π/180 = π/2 ≈ 1.57 radians.

Q3: What is the maximum recommended pulling tension?
A: Typically 0.008-0.015 lb per circular mil of conductor cross-section, or consult cable manufacturer specifications.

Q4: Does this account for multiple bends?
A: For multiple bends, calculate sequentially: T_out from first bend becomes T_in for next bend, and so on.

Q5: When should I use this calculation?
A: For planning cable pulls through conduits with bends, selecting appropriate pulling equipment, and preventing cable damage during installation.