The following recommendations are based on a study sponsored by ICEA and can be modified with experience and if more information is known:
A. Maximum Pulling Tension on Cable
With pulling eye attached to copper conductors, the maximum pulling strain in pounds should not exceed .008 times CMA.
With pulling eye attached to aluminum conductors, the maximum pulling strain in pounds should not exceed 0.006 times CMA. (Tm = 0.008 x N x CM)
Where: Tm = max. tension, lb.
CM = cir-mil area of each conductor
With cable grip over non-leaded cable, the maximum pulling strain should not exceed 1,000 lbs. and may not exceed the maximum tension based on 0.008 or 0.006 x total conductor area.
B. Maximum Permissible Pulling Length (Lm = Tu/CW) Where: Lm = pulling length, feet (straight section) Tm = maximum tension, lb. W = weight of cable per foot, lb. C = coefficient of friction (usually 0.5)
C. Pulling tension must not exceed the smaller of these values:
Allowable tensions on the conductor
Allowable tensions on pulling device
Allowable sidewall pressure
Pulling Eye: T (Cu) = Number of Conductors x circular mils x .008
Basket-Group: T = 1000 lbs. per grip
Sidewall Pressure: p = 300 lbs. x radius of curve in feet