/images/product_buttons/MissingImage_button.gif/images/southwire_100x70.jpgMaximum Wire and Cable Pulling TensionsMaxWireCablePullingTensions.htm
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Maximum Wire and Cable Pulling Tensions

Cable damaged during installation can cause service failures. Calculations should be made to indicate whether the pull looks easy or impossible. When a marginal situation is encountered, the entire pull should be reviewed. A final decision should be made based on factors known to the end user and installer. Pulling tensions may be evaluated by determining the maximum tension based on the pulling device used, and the maximum tension that can be applied to the conductors. The lesser of these two values is the maximum allowable tension. After calculating the pulling tensions, sidewall pressures may be calculated.

Do not exceed the allowable tension stated by the manufacturer of the pulling device or 10,000 pounds, whichever is less. Do not use metallic shielding wires, tapes or braids, or armor not designed for the purpose, in pulling tension calculations.

FORMULAS

SINGLE CONDUCTOR:

T = S * A (pounds)

Where:
T = conductor tension, lbs
S = conductor stress, lbs/cmil (Table 1)
A = conductor area, cmil (Table 2)

MULTIPLE CONDUCTORS:

T = N * S * A (pounds) for 3 or less conductors
T = (0.8) * N * S * A (pounds) for more than 3 conductors

Where:
N = number of conductors

NOTE: Pulling different conductor sizes at the same time is not recommended if the conductor size or other cable characteristics are significantly different. If different size conductors must be pulled, it must be done with care.


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TABLE 1
MAXIMUM ALLOWABLE CONDUCTOR STRESS 

Cable Type 

Material 

Temper 

lbs/cmil

All  

Copper 

soft 

0.008 

Power 

Aluminum 

Hard 

0.008 

Power 

Aluminum 

3/4 hard 

0.006 

Power 

Aluminum 

AA-8000 

0.006 

URD  

Aluminum  

1/2 hard 

0.003 

Solid 

Aluminum

Soft 

0.002 

Note: 3/4 hard aluminum is allowed for power cable. The 1990 NEC defines use of AA-8000 for solid (8, 10 & 12 AWG) and stranded (8 AWG through 1000 kcmil) conductors.

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TABLE 2 
CONVERSION FROM AWG to CMIL
  
(Solid and concentric stranded Aluminum
and Copper Conductors)

AWG 

cmil 

12 

6,530

10 

10,380 

16,510

26,240

41,740

52,620

66,360

83,690

1/0 

105,600 

2/0 

133,100

3/0

167,800 

4/0 

211,600 

   

kcmil

cmil 

250 

250,000

300

300,000 

350 

350,000 

400

400,000 

500 

500.000 

600 

600,000 

750 

750,000 

800

800,000 

1000 

1,000,000