Enter the coefficient of friction, conduit inner diameter, length of conduit, material factor, and wire size into the calculator to determine the wire pull force.

Wire Pull Force Formula

The following equation is used to calculate the Wire Pull Force.

WPF = u*d^2*L/(M*I)

  • Where WPF is the wire pull force (lbs)
  • u is the coefficient of friction
  • d is the conduit inner diameter (in)
  • L is the length of the run (ft)
  • M is the material factor
    • .008 for copper
    • .006 for aluminum
  • I is the wire size (gauge)

What is a Wire Pull Force?


A wire pull force is the amount of force it takes to pull a wire 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 calculate Wire Pull Force.

First, determine the coefficient of friction. For this example, the coefficient of friction is .75.

Next, determine the inner diameter. In this case, the inner diameter is 5 inches.

Next, determine the length of the run. The conduit run length is 40 ft.

Next, determine the material factor. For this example, the material is copper, so the factor is .008.

Next, determine the wire size (gauge). This wire has a gauge of 15.

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

WPF = u*d^2*L/(M*I)

WPF = .75*5^2*40/(.008*15)

WPF = 6,250 lbs