Cable pulling force calculation

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Expat

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Gents, hello, I'm new here and I'm surprised I haven't found this place before!

Anyway let me get to the meat of the issue here. Now, before we begin PLEASE KNOW that I realize that this pull is nigh impossible. In fact, that is why I am here, I need to be able to calculate the pull data so that I can prove to others that my recommendations are well founded.

Ok, here's the data

4" PVC Sch 40 conduit

300' pull

Superior Essex 2400 pair cable, dia 3.59", 8.7 lbs per foot Max tension 15000 lbs.

So, I have searched all over the internet for a cable calculator that handles loads this high, but am found wanting. I'd purchase Greenlee's program, but I can't find the option to download.

Anyone got some help?
 
http://www.electrician2.com/electa1/ductwirepull.html


http://ecmweb.com/mag/electric_simple_calculations_cable/

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.
Click to expand...
 
Expat said:
Gents, hello, I'm new here and I'm surprised I haven't found this place before!

Anyway let me get to the meat of the issue here. Now, before we begin PLEASE KNOW that I realize that this pull is nigh impossible. In fact, that is why I am here, I need to be able to calculate the pull data so that I can prove to others that my recommendations are well founded.

Ok, here's the data

4" PVC Sch 40 conduit

300' pull

Superior Essex 2400 pair cable, dia 3.59", 8.7 lbs per foot Max tension 15000 lbs.

So, I have searched all over the internet for a cable calculator that handles loads this high, but am found wanting. I'd purchase Greenlee's program, but I can't find the option to download.

Anyone got some help?
Click to expand...


I believe you are looking at the force required to pull the cable 300ft without damaging the cable correct..or are you worried about the conduit being damaged..
 
Well, since the diameter of the cable is 3.59", and the ID of the conduit is 4", and the weight of the cable is 8.7 lb per foot, I'm fully expecting any pulling force calculator to tell me "no way, bub" and give me an astronomical pulling force calculation.

I expect the force to be far greater than the 15k lbs that the cable can withstand, or to be greater than my Condux tugger can pull, or to be greater than the conduit can withstand. The conduit will be over 90% filled by this one cable and I need to prove to "others" that size is not the only concern, but friction/pulling force is the main impediment to pulling this cable.
 
Contact Superior Essex and see if they can help. (of course they'll tell you it can't be done, so that is probably not the best idea ;))

Roger
 
6 inch conduit &long sweeps

6 inch conduit &long sweeps

Well not to be a pain ,but they make 6 inch conduit ? I know its already in the ground sorry but i hope its long sweeps and you got lots of soap ? dont pull it as it may not come back out !! best to ya
 
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We're actually building the plant now, but the manholes and duct are already set in stone, so to speak. Customer demands and such.

Well, I ordered Polywater's $129 software, let's see how that works out.
 
I ran your installation on my Polywater program. I assumed a 4 ft 90 degree bend at both ends. You can choose several Cof of Friction to use depending on which Poltwater product you use.
Using Polywater Lube with the max COF of 0.35.
With a COF of 0.35 Pulling T = 1680 lbs and SWP = 402 lbs.

With no lube the max COF was 0.60.
With COF of 0.60 Pulling T = 4030 and SWP = 1008 lbs
 
Expat said:
. . . 4" PVC Sch 40 conduit = 3.998" I.D. nominal

300' pull = no problem

Superior Essex 2400 pair cable, dia 3.59", 8.7 lbs per foot Max tension 15000 lbs. = no problem . . .
Click to expand...
Assuming large radius bends and you fall under the NESC instead of the NEC this may work. Have you ever noticed the cable jacket pucker a little when you bend it? I also puckers in a bend while pulling. With only 0.408" nominal (that means both the cable and conduit will vary a little), you may run into trouble in one of the bends unless the pull is straight. :smile:
 
As mentioned, Superior Essex recommends bend radius to be no smaller than 12X the cable OD for this cable (Sealpic -FSF / RDUP PE-89). This puts you at 43" minimum (3.59 x 12= 43.08), so you have choice of 48" or 60" LR elbows.
 
So a littel more info on the conduit installed..I believe your tugger will pull it but I believe you are going to need four guys on the feed end to make it easier..1 to pull on the spool to provide slack..2 to man handle the cable and add a pushing force..1 man to lub the cable as it goes in..I would also put a rag soaked in lub on a rope and swab the inside of the pipe first so as to pre lube the entire pipe and to wipe out any obstructions..
 
swab and lub

swab and lub

cschmid said:
. . . I would also put a rag soaked in lub on a rope and swab the inside of the pipe first so as to pre lube the entire pipe and to wipe out any obstructions..
Click to expand...
The way that is stated, it sounds like a swab and lub is not normally done on long UG pulls. I thought that was always done to make the pull easier and to clean out sand, gravel, dirt, and soda cans. Isn't that step SOP? :-?
 
charlie said:
The way that is stated, it sounds like a swab and lub is not normally done on long UG pulls. I thought that was always done to make the pull easier and to clean out sand, gravel, dirt, and soda cans. Isn't that step SOP? :-?
Click to expand...

well It is standard for me..that normally means not for everyone..
 
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