The following recommendations are based on a study sponsored by the ICEA. These recommendations may be modified if experience and more exact information so indicate.
A. Maximum Pulling Tension on a Cable:
| 1. | With pulling eye attached to copper conductors, the maximum pulling strain should not exceed 0.008 times cir-mil area. |
| 2. | With pulling attached to aluminum conductors, the maximum pulling strain should not exceed 0.006 times cir-mil area. Tm = max tension, pounds N = number of conductors CM = cir-mil area of each conductor |
| 3. | With cable grip over lead sheath, the maximum pulling strain should not exceed 1500 lbs./sq. inch of lead sheath cross sectional area for commercial lead. t = sheath thickness, inches D = overall diameter of cable, inches |
| 4. | With cable grip over non-leaded cable, the maximum pulling strain should not exceed 1000 pounds and may not exceed the maximum tension based on 0.008 or 0.006 x total conductor area. |
| 5. | When more than 3 conductors are pulled together, the maximum pulling tension should be reduced 20%. |
B. Maximum Permissible Pulling Length:
Lm = pulling length, feet (straight section)
Tm = maximum tension, pounds
W = weight of cable per foot, pounds
f = coefficient of friction (usually 0.5)
C. Pulling Tension Requirements in Ducts:
| 1. | For straight duct sections, the pulling tension equals the length of duct multiplied by the weight per foot of cable and the coefficient of friction (paragraph B above). |
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| 2. | For curved sections, the multipliers given below shall be applied to the tension calculated for the straight section preceding the bend.
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| 3. | The maximum pulling tension in pounds shall not exceed the following factor times the radius of curvature of the bend expressed in feet.
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