Cable Sag Tension Calculator

Cable Sag Tension Formula:

\[ H = \frac{w \times S^2}{8 \times d} \]

Tension (H):

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1. What is the Cable Sag Tension Formula?

The cable sag tension formula calculates the horizontal tension in a cable or wire when it's suspended between two points. This formula is essential in engineering applications such as power line installation, suspension bridges, and cable systems.

2. How Does the Calculator Work?

The calculator uses the cable sag tension formula:

\[ H = \frac{w \times S^2}{8 \times d} \]

Where:

\( H \) — Horizontal tension (Newtons)
\( w \) — Weight per unit length (N/m)
\( S \) — Span length between supports (meters)
\( d \) — Sag or vertical deflection (meters)

Explanation: The formula assumes a parabolic cable shape and neglects cable elasticity, which is valid for most engineering applications with small sags relative to span length.

3. Importance of Cable Tension Calculation

Details: Accurate tension calculation is crucial for structural safety, determining appropriate cable size, ensuring proper sag for clearance requirements, and predicting cable behavior under various load conditions.

4. Using the Calculator

Tips: Enter weight per unit length in N/m, span length in meters, and sag in meters. All values must be positive numbers. The calculator will compute the horizontal tension in Newtons.

5. Frequently Asked Questions (FAQ)

Q1: What assumptions does this formula make?
A: The formula assumes a parabolic cable shape, uniform weight distribution, and neglects cable elasticity and temperature effects.

Q2: When is this formula not accurate?
A: For large sags relative to span length, when cable elasticity is significant, or when additional loads (like ice or wind) are present.

Q3: How does temperature affect cable tension?
A: Temperature changes cause cable expansion/contraction, changing both sag and tension. Special calculations are needed for temperature variations.

Q4: Can this be used for inclined spans?
A: The basic formula is for level spans. Different calculations are needed for spans with significant elevation differences.

Q5: What safety factors should be applied?
A: Engineering standards typically require safety factors of 2-5 depending on the application and consequences of failure.