Pulling Cable

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mripoll

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The elctrical contractor is using their truck to pull wire through conduit. They are attaching nylon rope to the end of the wire, running the rope over a pully then attaching the rope to the truck to pull the wire. Is this within NEC code.
Thank You,
Michael Ripoll
 
If you're concerned about excessive pulling force use a rope that will break before the conductors can be damaged. ;)
 
There is not a code issue here, but some serious safety issues. You do not have near as much control when using a truck as when using a tugger. You have a lot more exposed rope when using a truck. The rope is probably not a rope suitable for pulling cable. It is likely a dynamic rope that will store a lot of energy that will be released if the rope breaks and a dynamin rope tends to pull in "jerks" that can injure the cable feeder person. One of the Greenlee tugger manuals says for a 5,500 pound rated tugger a dynamic rope stores enough energy to launch a standard size car 14 stories. Even the correct rope stores enough energy to send that same car two stories.
 
mripoll said:
The elctrical contractor is using their truck to pull wire through conduit. They are attaching nylon rope to the end of the wire, running the rope over a pully then attaching the rope to the truck to pull the wire. Is this within NEC code.
Thank You,
Michael Ripoll
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As long as the minimum bending radius, pulling tension, etc. are not violated the cable will not be damaged. As far as the cable is concerned, it doesn't care what is pulling it as long as it doesn't pull too hard. :)

I agree with the others that there would be some safety concerns, though.
 
don_resqcapt19 said:
There is not a code issue here, but some serious safety issues. You do not have near as much control when using a truck as when using a tugger. You have a lot more exposed rope when using a truck. The rope is probably not a rope suitable for pulling cable. It is likely a dynamic rope that will store a lot of energy that will be released if the rope breaks and a dynamin rope tends to pull in "jerks" that can injure the cable feeder person. One of the Greenlee tugger manuals says for a 5,500 pound rated tugger a dynamic rope stores enough energy to launch a standard size car 14 stories. Even the correct rope stores enough energy to send that same car two stories.
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Don is right, more of a safety issue than anything. Make sure they meg all conductors. In the past I have used trucks, forklifts, manlifts, come alongs, chain hoists whatever would get the wire in the pipe. With that said I run my own company now and my guys get all the best equipment and dont have to worry about using a truck to pull with.
 
I have seen and been part of some pretty interesting wire pull setups....pickup truck not uncommon, have used chuggers, four wheelers, pulled lots by hand:mad: used farm tractors, and once a Caterpilliar 953 trackloader.....pickup truck wouldnt pull it....broke chugger on the pull.....so I told foreman to get GC's trackloader, to which he replied "I dont know how to drive that".....I can drive anything with a motor.....so I spent the day on a trackloader.....:D
 
One thing to look for is if there is a specification in the construction documents about pulling cables.

Sometimes, there's a requirement that only so much force be applied to the cables. This requires a tugger with a force gauge. You may even need to go so far as to document the force applied during the pull.

Then you need to spring for one of these:

00967.JPG
 
LarryFine said:
Ok. Where do we find the tensile strength of various conductors? :cool:
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Tensile strength of the conductors doesn't matter. You can't pull them almost to the breaking point anyway without having already done serious damage.

There are formulas for calculating the maximum pulling tension a conductor can withstand without permanent damage, but don't bother with those. Just ask the manufacturer.

Go to servicewire.com and download their catalog, then look at page 77 if you're interested.
 
It would be highly unlikely that you would reach anywhere near the tensile strength of the conductors before you exceeded the maximum allowable side wall pressure on the insulation.

That is the reason for large radius sweeps, the large radius sweep spreads the side wall pressure out over a larger area of insulation.


(BTW I am talking power conductors, communication cables are another story altogether)
 
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