The Calculator uses Equations based on a study by the ICEA.
Observations:
 The radius of bend does not effect the pulling tension.
 The size of raceway does not effect the pulling tension or the sidewall pressure. This assumes that the raceway is not overfilled and is in compliance with the NEC.
 The sidewall pressure is effected by the coefficient of friction and the radius of the bend. The larger the radius the less the sidewall pressure.
 For long pulls with larger conductors sweep bends are usually necessary to lower the sidewall pressure to within allowable limits. For these types of pulls radii of standard benders cause the sidewall pressure to exceed the maximum in most cases.
 The end that is the farthest away from the bends will have the least pulling tension.
 Bends have a multiplying effect on the incoming tension to the bend.
 Although there are no ICEA data for pushing in conductors at the feed end there is substantial evidence that this method has a substantial effect on decreasing the total pulling tension at the pull end.
Wire Tension Pull Calculator for
Straight Pulls
(Read reference material below for explanations.) by electrician2.com 
Pulling Straight Up 

Pulling Straight Down 

Pulling at a 30 or 45 degree angle 

Pulling Horizontal and Curvature Pulls 

Pulling Horizontal with Lubricant 

For larger wires add 1.09, the default. This approximately compensates for the weight of the insulation. 
If weight of 1 ft of wire(s) or cable(s) is known use the multiplier
that gives the nearest weight per foot for all the wires or cables the
same as known value. The default weight with multiplier set to 1.00
is 0.321 Lbs per cubic inch of copper and 0.10 Lbs. per cubic inch of Aluminum.
The cubic inch per foot calculation is found from the circular mil
area for the selected size of conductor. The weight and not the circular
mil area is used in subsequent calculations for Pulling Tension.
For other weights that are lighter, for instance fiber optic cables, use
a negative multiplier. The weight multiplier uses the size of conductors
as a reference only. This way the calculator can be used for
calculating Pulling Tension for communications and fiber optic cables.
The Maximum Pulling Tension is calculated as 0.008 times the circular mil area for copper and 0.006 times the circular mil area for aluminum. The Maximum Pull Tension and Maximum Pulling Length are not adjustable and would not be correct for fiber optic cables, but the Pulling Tension based on weight and coefficient of friction would be correct, likewise for the curvature calculator. 
This example will be done first using the given radius of 120 inches
then attempted using a Greenlee 881 with a radius of 16 inches.
It will be found that the 16 inch radius causes too high a sidewall pressure and that a 36 or 48 inch inch factory sweep will satisfy the given conditions.
Part I
Using Given ConditionsStep 1
Set add multiplier to 1.40 to get 6.35 Lb/Ft for conductor weight
for 3 1/C 500 kcmil
Calculate pull tension at first straight section at Feed End.
Coefficient of Friction = 0.5
Length = 220 feet
Calculated pull tension = 635 Lbs.Step 2
Calculate pull tension straight section past first 45 degree bend
Coefficient of Friction = 0.5
Length = 70 feet
Calculated pull tension = 222 Lbs.Step 3
Calculate pull tension at first 45
Coefficient of Friction = 0.5
Pull tension at feed straight section = 635 Lbs.
Angle of Bend = 45 degrees
Radius = 120 inches
Pull tension at pull end straight section = 222 Lbs
Total Calculated pull tension = 1162 Lbs.
Sidewall pressure is 139 Lb.
Maximum allowed sidewall presure is 3000 Lb.Step 4
Calculate pull tension at straight section past first 90
Coefficient of Friction = 0.5
Length = 100 feet
Calculated Pull Tension = 317Step 5
Calculate pull tension at first 90
Coefficient of Friction = .5
Pull Tension at feed straight section = 1162 Lbs
Angle = 90 degrees
Radius = 120 inches
Pull Tension at pull straight section = 317
Total Calculated Pull Tension = 2865 Lb.
Sidewall pressure is 255 Lb.
Maximum allowed sidewall presure is 3000 Lb.The example shows 2863 Lb.
There is a .07 per cent error that is accountable to round off error.
Part II
The same problem as Example I except with a radius of 16 inches.
Step 1
Set add multiplier to 1.40 to get 6.35 Lb/Ft for conductor weight
for 3 1/C 500 kcmil
Calculate pull tension at first straight section at Feed End.
Coefficient of Friction = 0.5
Length = 220 feet
Calculated pull tension = 635 Lbs.Step 2
Calculate pull tension straight section past first 45 degree bend
Coefficient of Friction = 0.5
Length = 70 feet
Calculated pull tension = 222 Lbs.Step 3
Calculate pull tension at first 45
Coefficient of Friction = 0.5
Pull tension at feed straight section = 635 Lbs.
Angle of Bend = 45 degrees
Radius = 16 inches
Pull tension at pull end straight section = 222 Lbs
Total Calculated pull tension = 1162 Lbs.
Sidewall pressure is 705 Lb.
Maximum sidewall pressure allowed is 300 x 1.333 = 400 Lb.Try 36 inch radius factory sweeps and redo calculation.
Step 3 repeated with 36 inch radius
Calculate pull tension at first 45
Coefficient of Friction = 0.5
Pull tension at feed straight section = 635 Lbs.
Angle of Bend = 45 degrees
Radius = 36 inches
Pull tension at pull end straight section = 222 Lbs
Total Calculated pull tension = 1162 Lbs.
Sidewall pressure is 313 Lb.
Step 4
Calculate pull tension at straight section past first 90
Coefficient of Friction = 0.5
Length = 100 feet
Calculated Pull Tension = 317Step 5
Calculate pull tension at first 90
Coefficient of Friction = .5
Pull Tension at feed straight section = 1162 Lbs
Angle = 90 degrees
Radius = 36 inches
Pull Tension at pull straight section = 317
Total Calculated Pull Tension = 2865 Lb..
Sidewall pressure is 849 Lb.
Maximum sidewall pressure allowed is 900 Lb.
Figure Shows Vertical Plane
For a Floating Window with the Pull Calculator Click Here.
(can be readily applied to the examples as you move through them)
Method IStep 1
Calculate pull tension at first straight section at Feed End.
Coefficient of Friction = 1.0
Length = 18 feet
Calculated pull tension = 83 Lbs.Step 2
Calculate pull tension straight section past first 90.
Coefficient of Friction = .5
Length = 20 feet
Calculated pull tension = 46 Lbs.Step 3
Calculate pull tension at first 90
Coefficient of Friction = .5
Pull tension at feed straight section = 83 Lbs.
Angle of Bend = 90 degrees
Radius = 18 inches
Pull tension at pull end straight section = 46 Lbs
Total Calculated pull tension = 228 Lbs.Step 4
Calculate pull tension at straight section past second 90
Coefficient of Friction = .0001
Length = 10 feet
Calculated Pull Tension = 0Step 5
Calculate pull tension at second 90
Coefficient of Friction = .5
Pull Tension at feed straight section = 208 Lbs
Angle = 90 degrees
Radius = 18 inches
Pull Tension at pull straight section = 0
Total Calculated Pull Tension = 499 Lbs.
Step 6
Calculate last 10 feet of straight section to find contributing weight.
Coefficient of Friction = 1.0
Length = 10 feet
Calculated pull tension = 46 Lbs.Total Tension Required after conductors arrive at pull end.
499  46 Lbs = 453 Lbs.
Pull tension would decrease from 499 to 453 Lbs after conductors passed second 90.
Method II
Use second person that pushes 50 Lbs at feed end
Step 1
Calculate pull tension at first straight section at Feed End.
Coefficient of Friction = 1.0
Length = 18 feet
Calculated pull tension = 83 Lbs.
With 50 Lb. push
Pull tension = 83  50 = 33 Lbs.Step 2
Calculate pull tension straight section past first 90.
Coefficient of Friction = .5
Length = 20 feet
Calculated pull tension = 46 Lbs.Step 3
Calculate pull tension at first 90
Coefficient of Friction = .5
Pull tension at feed straight section = 33 Lbs.
Angle of Bend = 90 degrees
Radius = 18 inches
Pull tension at pull end straight section = 46 Lbs
Total Calculated pull tension = 118 Lbs.Step 4
Calculate pull tension at straight section past second 90
Coefficient of Friction = .0001
Length = 10 feet
Calculated Pull Tension = 0Step 5
Calculate pull tension at second 90
Coefficient of Friction = .5
Pull Tension at feed straight section = 118 Lbs
Angle = 90 degrees
Radius = 18 inches
Pull Tension at pull straight section = 0
Total Calculated Pull Tension = 258 Lbs.
Step 6
Calculate last 10 feet of straight section to find contributing weight.
Coefficient of Friction = 1.0
Length = 10 feet
Calculated pull tension = 46 Lbs.Total Tension Required after conductors arrive at pull end.
258  46 Lbs = 212 Lbs.
Pull tension would decrease from 258 to 212 Lbs after conductors passed second 90.
Method III Reverse Pull and Feed Ends
Step 1
Calculate pull tension at first straight section at Feed End.
Coefficient of Friction = 1.0
Length = 10 feet
Calculated pull tension = 46 Lbs.Step 2
Calculate pull tension straight section past first 90.
Coefficient of Friction = .5
Length = 20 feet
Calculated pull tension = 46 Lbs.Step 3
Calculate pull tension at first 90
Coefficient of Friction = .5
Pull tension at feed straight section = 46 Lbs.
Angle of Bend = 90 degrees
Radius = 18 inches
Pull tension at pull end straight section = 46 Lbs
Total Calculated pull tension = 147 Lbs.Step 4
Calculate pull tension at straight section past second 90
Coefficient of Friction = .0001
Length = 18 feet
Calculated Pull Tension = 0Step 5
Calculate pull tension at second 90
Coefficient of Friction = .5
Pull Tension at feed straight section = 147 Lbs
Angle = 90 degrees
Radius = 18 inches
Pull Tension at pull straight section = 0
Total Calculated Pull Tension = 322 Lbs.Step 6
Calculate last 18 feet of straight section to find contributing weight.
Coefficient of Friction = 1.0
Length = 18 feet
Calculated pull tension = 83 Lbs.Total Tension Required after conductors arrive at pull end.
322  83 Lbs = 239 Lbs.
Pull tension would decrease from 322 to 239 Lbs after conductors passed second 90.
Method IV Reverse Pull and Feed Ends
and use second person pushing 50 Lbs at feed end.Step 1
Calculate pull tension at first straight section at Feed End.
Coefficient of Friction = 1.0
Length = 10 feet
Calculated pull tension = 46 Lbs.
Pull tension = 46  50 =  4 LbsStep 2
Calculate pull tension straight section past first 90.
Coefficient of Friction = .5
Length = 20 feet
Calculated pull tension = 46 Lbs.Step 3
Calculate pull tension at first 90
Coefficient of Friction = .5
Pull tension at feed straight section =  4 Lbs.
Angle of Bend = 90 degrees
Radius = 18 inches
Pull tension at pull end straight section = 46 Lbs
Total Calculated pull tension = 37 Lbs.Step 4
Calculate pull tension at straight section past second 90
Coefficient of Friction = .0001
Length = 18 feet
Calculated Pull Tension = 0Step 5
Calculate pull tension at second 90
Coefficient of Friction = .5
Pull Tension at feed straight section = 46 Lbs
Angle = 90 degrees
Radius = 18 inches
Pull Tension at pull straight section = 0
Total Calculated Pull Tension = 101 Lbs.Step 6
Calculate last 18 feet of straight section to find contributing weight.
Coefficient of Friction = 1.0
Length = 18 feet
Calculated pull tension = 83 Lbs.Total Tension Required after conductors arrive at pull end.
101  83 Lbs = 18 Lbs.
Pull tension would decrease from 101 to 18 Lbs after conductors passed second 90.
Summary:
Method Push at Feed
End in LbsPull Tension in Lbs. I ( Fig 1) 0 499 II (Fig. 1 with 2 persons) 50 258 III (Reverse ends) 0 322 IV (Reverse ends with 2 persons) 50 101 Conclusion:
This problem demonstrates why "one push is worth four pulls."
 Use Method IV if two people are available  Reverse Pull and Feed Ends in Figure 1 and use second person pushing at feed end.
 Use Method III if two people are not available  Reverse Pull and Feed Ends in Figure 1.
Example 3
Radius of Bend = 16 inches for Greenlee 881 Bender
Method IFor a Floating Window with the Pull Calculator Click Here.
(can be readily applied to the examples as you move through them)
Pull from A to BStep 1
Calculate pull tension at first straight section at Feed End.
Coefficient of Friction = .0001
Length = 8 feet
Calculated pull tension = 0 Lbs.Step 2
Calculate pull tension straight section past first 90.
Coefficient of Friction = .2
Length = 80 feet
Calculated pull tension = 105 Lbs.Step 3
Calculate pull tension at first 90
Coefficient of Friction = .5
Pull tension at feed straight section = 0 Lbs.
Angle of Bend = 90 degrees
Radius = 16 inches
Pull tension at pull end straight section = 105 Lbs
Total Calculated pull tension = 105 Lbs.Step 4
Calculate pull tension at straight section past 60 degree kick
Coefficient of Friction = .2
Length = 6 feet
Calculated Pull Tension = 8Step 5
Calculate pull tension at 60 degree kick
Coefficient of Friction = .5
Pull Tension at feed straight section = 105 Lbs
Angle = 60 degrees
Radius = 16 inches
Pull Tension at pull straight section = 8
Total Calculated Pull Tension = 185 Lbs.Step 6
Calculate pull tension at straight past second 90
Coefficient of Friction = 1.0
Length = 6 feet
Calculated Pull Tension = 40Step 7
Calculate pull tension at second 90
Coefficient of Friction = .5
Pull Tension at feed straight section = 185 Lbs
Angle = 90 degrees
Radius = 16 inches
Pull Tension at pull straight section = 40
Total Calculated Pull Tension = 445 Lbs.Method II
Pull from A to B
Use Two persons pushing about 80 Lb. at AThis method was done by hand in Nome, Alaska in 1998 using three people,
at the FAA Station for D&N Electric out of Georgia.
Two persons pushed and one pulled with a rope. Gerald Newton was the puller.
The pull went smoothly until the last 90 that multiplied the tension from about 67 Lb. to 187 Lb. The last 90 was pulled using a unistrut lever bar on the rope. The 187 Lb. had to be pulled to get through the last 90 and it felt like 187 Lb. because it was just a little over what I can pull with the rope over my shoulders. This is the field scientific method!
Step 1
Calculate pull tension at first straight section at Feed End.
Coefficient of Friction = .0001
Length = 8 feet
Calculated pull tension = 0 Lbs.Step 2
Calculate pull tension straight section past first 90.
Coefficient of Friction = .2
Length = 80 feet
Calculated pull tension = 105 Lbs.
With the 80 Lb push at A transferred around the 90
Pull tension = 105  80 = 35 Lb.Step 3
Calculate pull tension at first 90
Coefficient of Friction = .5
Pull tension at feed straight section = 0 Lbs.
Angle of Bend = 90 degrees
Radius = 16 inches
Pull tension at pull end straight section = 35 Lbs
Total Calculated pull tension = 35 Lbs.Step 4
Calculate pull tension at straight section past 60 degree kick
Coefficient of Friction = .2
Length = 6 feet
Calculated Pull Tension = 8Step 5
Calculate pull tension at 60 degree kick
Coefficient of Friction = .5
Pull Tension at feed straight section = 35 Lbs
Angle = 60 degrees
Radius = 16 inches
Pull Tension at pull straight section = 8
Total Calculated Pull Tension = 67 Lbs.Step 6
Calculate pull tension at straight past second 90
Coefficient of Friction = 1.0
Length = 6 feet
Calculated Pull Tension = 40Step 7
Calculate pull tension at second 90
Coefficient of Friction = .5
Pull Tension at feed straight section = 67 Lbs
Angle = 90 degrees
Radius = 16 inches
Pull Tension at pull straight section = 40
Total Calculated Pull Tension = 187 Lbs.
Method III
Pull from B to AStep 1
Calculate pull tension at first straight section at Feed End.
Coefficient of Friction = .0001
Length = 6 feet
Calculated pull tension = 0 Lbs.
Step 2
Calculate pull tension straight section past first 90.
Coefficient of Friction = .2
Length = 6 feet
Calculated pull tension = 8 Lbs.Step 3
Calculate pull tension at first 90
Coefficient of Friction = .5
Pull tension at feed straight section = 0 Lbs.
Angle of Bend = 90 degrees
Radius = 16 inches
Pull tension at pull end straight section = 8 Lbs
Total Calculated pull tension = 8 Lbs.Step 4
Calculate pull tension at straight section past 60 degree kick
Coefficient of Friction = .2
Length = 80 feet
Calculated Pull Tension = 105Step 5
Calculate pull tension at 60 degree kick
Coefficient of Friction = .5
Pull Tension at feed straight section = 8 Lbs
Angle = 60 degrees
Radius = 16 inches
Pull Tension at pull straight section = 105
Total Calculated Pull Tension = 119 Lbs.Step 6
Calculate pull tension at straight past second 90
Coefficient of Friction = 1.0
Length = 8 feet
Calculated Pull Tension = 52Step 7
Calculate pull tension at second 90
Coefficient of Friction = .5
Pull Tension at feed straight section = 119 Lbs
Angle = 90 degrees
Radius = 16 inches
Pull Tension at pull straight section = 52
Total Calculated Pull Tension = 313 Lbs.
For excellent References
try:http://www.houwire.com/catalog/l6.html
or
Bending Radii and Pulling Tensions 

Power Cables
Without Metallic Shielding
Power Cables With Metallic Shielding
The following recommendations are based on a study sponsored by ICEA. These recommendations may be modified if experience and more exact information so indicate. A. Maximum Pulling Tension On Cable
TM =0.006 x n x CM, for aluminum Done in Calculator where TM = max. tension, lb. n = number of conductors CM = cirmil area of each conductor
t = sheath thickness, inches D = overall diameter of cable, inches B. Maximum Permissible Pulling Length
where
C. Pulling Tension Requirements in Ducts
where T2 = tension for straight section at pulling end, lb. T1 = tension for straight section at feeding end, lb. Tt = total tension a = angle of bend in radian (1 radian = 57.3 deg.) f = coefficient of friction (usually 0.5) e^{fa} = log10^{1} x (fa)/2.303 e^{fa} = The number whose logarithm to the base ten is fa/2.303 e = Naperian logarithm base (= 2.718) The value of e^{fa} can be found using JavaScript:
where value1 = 2.718 and value2= fa D. Sidewall PressureSidewall Pressure = T / R Done in Calculator E. Pulling Tensions Must Not Exceed The Smaller of These Values:
Pulling Eye: T (Cu) = Number conductors x circular mills x .008 BasketGrip: T = 1000 lbs. per grip Sidewall Pressure: P = 300 pounds x radius of curve in feet. 







SiteRite Hand Bender






SiteRite II Hand
Bender






555 EMT







555 IMC

43/8"  41/2"  53/4"  71/4" 


555 Rigid







854 / 855 EMT







854 / 855 IMC/Rigid







880







882 EMT







882 IMC / Rigid







1800 / 1801 Rigid
& IMC















777









881






884
/ 885




























