Calculate cable pulling tension for a conduit run from cable weight, length, friction and total bend angle, with sidewall load and max pull length checks.

Examples are not universal; confirm friction for the cable and raceway.

Add up all bends in the run (e.g. two 90° bends = 180°). Blank means no bends.

Entry tension, radius and limits
Blank means 0.

Wire Pull Force Formula

The following equation can be used to estimate the wire pull force for a straight, level run (no bends).

WPF = u × w × L
  • Where WPF is the wire pull force (lbf)
  • u is the coefficient of friction
  • w is the cable weight force per unit length (lbf/ft)
  • L is the length of the run (ft)

What is a Wire Pull Force?

Definition:

A wire pull force (pulling tension) is the amount of force it takes to pull a wire or cable through a raceway. In other words, it’s the amount of force needed to pull a wire through a conduit, or through a hole in a wall filled with cable.

How to Calculate Wire Pull Force?

Example Problem:

The following example outlines the steps and information needed to estimate Wire Pull Force for a straight, level run.

First, determine the coefficient of friction. For this example, the coefficient of friction is 0.35.

Next, determine the cable weight per unit length. For this example, the cable weight is 2.0 lb/ft.

Next, determine the length of the run. The run length is 150 ft.

Finally, calculate the wire pull force using the formula above:

WPF = u*w*L

WPF = 0.35*2.0*150

WPF = 105 lbf