# Pulling Tensions

Given the amount of tension on cables going into a section of conduit (T1), the following equations determine the amount of tension on cables coming out of the conduit section (T2).

TIP: T1 of the conduit's first section only is the reelback or initial tension.

In subsequent sections of conduit, T, of a preceding section of conduit is T1 of the next section of conduit.

• T2 = Outgoing tension (lb)
• T1 = Incoming tension (lb)
• L = Length of conduit section (ft)
• K = Effective coefficient of friction (dimensionless)
• W = Total weight of cables (lb/ft)
• T = Offset angle (degrees)
• e = Base of natural logs (2.718)
• a = Bend angle (radians) (see table below)

Degrees

11.25°

.196

22.50°

.393

30°

.524

45°

.785

60°

1.047

90°

1.571

 A. For straight horizontal pulls: T2 = T1 + LWK B. For straight upward pulls: T2 = T1 + LW (sin T + K cos T) C. For straight downward pulls: T2 = T1 - LW (sin T - K cos T) D. For horizontal, upward, or downward pulls around bends: T2 = T1 eKa