What if a single pull is impossible?

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  #1  
Old 09-28-04, 05:28 PM
sandsmarc
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What if a single pull is impossible?

What do you do if you have to pull wire through so many angles that a single pull is an impossibility? How do you break it up?
 
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Old 09-28-04, 06:04 PM
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You rerun the conduit a different way. The NEC requires that there be no more than 360 degrees of bend between pull points. This is to avoid too much strain on the wires.
 
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Old 09-28-04, 06:06 PM
sandsmarc
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Between "pull points"? So can I create an extra pull point somewhere along the run and make 2 pulls?
 
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Old 09-28-04, 06:09 PM
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Yes. .....
 
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Old 09-29-04, 06:56 AM
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Just install junction boxes (straight or elbow) along the run. Avoid putting them in the underground run itself. You loss access to the junction box. They are cheap, costing around $2. This way you can effectively breakup the pull into several sections.

Code requires you to pull the cable though one complete run. I am not in total agreement with this. Sometimes it makes sense to divide the conduit up in logical sections, pull the cable and then connect up the sections. This would appear a better solution than pulled the s**t out of the cable and risk damage to the cable from the physical pull, rather than from the possible damage from re-connection of the conduit (for example, from the glue). But itís not code.
 
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Old 09-29-04, 07:31 AM
Snape
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Sounds funny that the code permits the pull to be done in one, what if the pull is of a far distance, surely it would be more logical to break the pull down in to sections to make it easyier and tidyier like already said.
 
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Old 09-29-04, 07:59 AM
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I believe that the concern is for possible cable damage by having the cable in the conduit while you are assembling it. Besides, it really doesn't save you anything to pull the cable through as you go. The pull is the same because a longer pull cord doesn't add any significant resistance to the pull, and the last part of the pull is the hardest anyway.
 
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Old 09-29-04, 08:33 AM
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In addition, if you are using non metallic conduit, SCH 80 PVC, the solvent glue used to join the sections of conduit will be hell on the insulation.

-Jon
 
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Old 09-30-04, 12:57 PM
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"Besides, it really doesn't save you anything to pull the cable through as you go."

I might be missing what you are saying but years ago we had a crew install (notice I didn't say pull) about 180 feet of cable through 24-90 degree bends (in a parking garage) by sliding the conduit and 90's on as they went. The guy in charge was quite proud of himself. Of course, there was no way to pull it out and the super made him figure out a different route, but it can be done. Incidently, he ran the new conduit as a "spare" and left his work of art as the working circuit.
 
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Old 10-01-04, 09:01 AM
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Art. 300.18, Raceway Installation, (A), Complete Runs----" "Raceways shall be installed complete ( end-to-end) prior to the installation of conductors."
 
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Old 10-01-04, 09:45 AM
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Tx, I agree. If you lay out all the cable in advance, and then slide the conduit on from the end, then that would make it easier. However, as pointed out multiple times, it's also illegal. If using PVC conduit, cable damage from the PVC glue would almost be a certainty.

What I was referring to is pulling ten feet of cable, installing ten feet of conduit, and then repeating. This is also illegal, and doesn't even make it easier.
 
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Old 10-01-04, 10:55 AM
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Pattbaa

Often in long runs on non-metallic conduit iin which large conductors will be pulled, it's best to use steel elbows because the intense friction of a pull/drag rope against the surface of a non-metallic elbow is sufficient for the rope cutting into the "wall" of the elbow where the rope moves along/across the surface.
 
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