Free tool · Electrical
Wire Pull Tension Calculator
List the run in the order you pull it: straight sections and bends. The calculator adds the tension from each section and shows what it has built up to at every step.
You supply the weight of what is being pulled and the friction coefficient. The numbers stay in your browser: nothing is saved or sent anywhere.
Run, in pull order
1. Straight
2. Bend
3. Straight
Estimated pulling tension at the end
— lb
Enter the weight and the lengths above.
The formulas
Straight section: tension out = tension in + (friction coefficient × weight per foot × length).
Bend: tension out = tension in × e^(friction coefficient × bend angle in radians). The angle in degrees is multiplied by π ÷ 180 first.
Sidewall bearing pressure at a bend: tension out ÷ bend radius, in pounds per foot of radius.
Tension starts at zero at the feed end and carries forward from one section to the next.
A worked example
Three conductors weigh 1.5 lb per foot in total, and the friction coefficient is 0.35. The run is 200 ft straight, then a 90 degree bend, then 100 ft straight.
After the first 200 ft the tension is 0.35 × 1.5 × 200 = 105 lb. The 90 degree bend multiplies it by e^(0.35 × 1.571), about 1.73, giving 182 lb. The last 100 ft adds 0.35 × 1.5 × 100 = 52.5 lb, for a total of about 234 lb.
Notice that the bend added more than the straight section before it. The same bend near the start of a long run costs far less than the same bend at the end, which is why the pull direction matters.
What to enter
Weight: the total weight per foot of every conductor or cable in the pull, from the manufacturer’s data. Add them together.
Coefficient of friction: depends on the cable jacket, the conduit and whether you use pulling lubricant. Use your cable maker’s guidance or your own experience. Lubricant usually lowers it.
What this does not do
This is a horizontal-run estimate. It does not handle vertical or inclined sections, and it does not tell you the maximum pulling tension or sidewall pressure your cable can take. Those limits come from the cable manufacturer, and the result here should always be checked against them. For a pull that is close to the limit, use the manufacturer’s tools or an engineer.
FAQ
Why does a bend multiply the tension instead of adding to it?
Friction on a bend grows with the tension already in the cable, so the effect compounds. That is why the bend uses an exponential, while a straight section only adds.
Does the order of the sections matter?
Yes. A bend near the end of the run multiplies a large tension, while the same bend near the start multiplies a small one. Pulling from the other end can give a lower total.
Can I use this for vertical pulls?
No. Vertical and inclined sections add or subtract the weight of the cable itself. This calculator covers horizontal runs only.
Is anything I type saved?
No. The calculation runs in your browser and nothing is stored or sent to us.
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Questions?
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