Conduit Pull Tension Calculator

Inputs

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Initial tension before the screened straight run and bend group. Use 0 if the setup starts slack, or an estimated feeder tension if already under load.
lbf
Installed cable or conductor bundle weight per route length. Include all pulled conductors in the bundle.
lb/ft
Equivalent straight conduit length before the bend group in this screening model.
ft
Sliding friction coefficient for cable jacket, conduit material, lubricant and field condition.
Sum of bend angles in the pull section. Two 90 degree bends equals 180 degrees.
°
Use the smallest effective radius where the cable bears on a bend.
in
Maximum allowed pulling tension from cable manufacturer data, pulling eye rating or project rule.
lbf
Maximum allowed sidewall bearing pressure at bends, usually provided by cable manufacturer guidance.
lb/ft

Results

Default result
Edit inputs
Final pull tension(T)
112.6lbf
Pass

Compare with the cable or pulling-eye tension limit.

Also computed

Sidewall pressure(SWP)Pass225.2lb/ft

Calculated from peak pull tension divided by the smallest bend radius.

Pull tension utilization(UT)Pass22.52%

Sidewall utilization(USWP)Pass75.07%

Straight-run friction force(Fstraight)17.5lbf

Fstraight = mu x cable weight x straight length.

Bend multiplier(Mbend)3.003x

Capstan multiplier e^(mu x theta) with theta = 3.142 rad.

Max straight length before limit(Lmax)171.2ft

sidewall pressure controls first with the entered cable limits.

Pull section friction screen start pull final tension bend capstan multiplier 23% pull limit 75% sidewall verify cable limits
Method notes 3 notes
  • Straight pull model: T_straight = T0 + mu x w x L.
  • Bend model: T_out = T_in x e^(mu x theta), where theta is total bend angle in radians.
  • This is a screening model. Real pull tension depends on route order, lubricant, cable jacket, conduit material, feed setup, pulling equipment, minimum bend radius, jamming and manufacturer limits.

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