paul.nixon@campassoc.com
New member
- Location
- Seattle, WA
What are the parameters for pulling cable. i.e. max distance, required pull boxes/hand holes.
Thank you
Thank you
Requirement for pulling cable
- Thread starter paul.nixon@campassoc.com
- Start date
- Status
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
That is a difficult question to answer, given the wide variety of wire and cable types and functions.
For power wiring covered by the NEC the most understandable requirement is that the total of all bends, elbows, etc. in the pull path must not exceed 360 degrees. To meet this limit you may need to provide additional intermediate pull points (even though the NEC does not require them to be used.)
The other practical limit is that the required pulling tension cannot exceed the allowable tension for the wiring type involved.
When boxes are provided as pull points the NEC sets minimum dimensions for those boxes, depending on wiring path geometry and size of cables or wires.
I do not feel confident trying to give any more guidance than that, since to a very large extent the practical requirements are learned through extensive experience and may be more strict than the Code requirements in some cases.
Hopefully a GC and EC involved in a project will provide feedback as to whether your design is feasible and whether changes would reduce the overall cost of the job.
For power wiring covered by the NEC the most understandable requirement is that the total of all bends, elbows, etc. in the pull path must not exceed 360 degrees. To meet this limit you may need to provide additional intermediate pull points (even though the NEC does not require them to be used.)
The other practical limit is that the required pulling tension cannot exceed the allowable tension for the wiring type involved.
When boxes are provided as pull points the NEC sets minimum dimensions for those boxes, depending on wiring path geometry and size of cables or wires.
I do not feel confident trying to give any more guidance than that, since to a very large extent the practical requirements are learned through extensive experience and may be more strict than the Code requirements in some cases.
Hopefully a GC and EC involved in a project will provide feedback as to whether your design is feasible and whether changes would reduce the overall cost of the job.
Fulthrotl
~Autocorrect is My Worst Enema.~
- Occupation
- E
power wire? fiber optic cable? greater or lesser than 600 volts?
case in point, it's common to push fiber optic thru conduits.
underground utilities can shove a backbone cable about 3 miles
with specialized equipment. uninterrupted conduit.
people can install code compliant (on paper) conduit systems
that are nearly impossible to get wire thru.
an example: a 400' long 2" conduit in a factory, with an LR in
the middle of it.
the LR is up in a corner, with the opening facing up, and an
air conditioning duct a foot above it. code compliant? yes?
can you put wire in it? theoretically. do you want to try? no.
NewtonLaw
Senior Member
- Location
- Honesdale, PA USA
Pulling any type of cable will have maximum stress levels that should not be exceeded due to obvious mechanical damage to the cable. This may be damage to the insulation system, conductor stretch, etc. It is not clear from your post as to what type of cable you are talking about but for primary power cables, the routine calculations are given by Southwire's Power Cable Installation Manual. The WEB address is given below.
Hope this helps,
Newton Law
http://www.southwire.com/documents/envirotectPowerCableInstallManual.pdf
As the others have indicated, you need to provide more information, your question is kind of like asking "what's the horse power of an engine".
Roger
Julius Right
Senior Member
- Occupation
- Electrical Engineer Power Station Physical Design Retired
See:
http://www.generalcable.com/assets/documents/North%20America%20Documents/Information-Center/Installation-Manuals/01$GC_Cable-Install_Manual_PowerControl_Cables-7_14.pdf
ch. 3.9 PHYSICAL LIMITATIONS OF CABLES
IEEE Std 525-1992 Annex A Sample calculations for cable pulling tensions
IEEE Std 422/2012
http://www.generalcable.com/assets/documents/North%20America%20Documents/Information-Center/Installation-Manuals/01$GC_Cable-Install_Manual_PowerControl_Cables-7_14.pdf
ch. 3.9 PHYSICAL LIMITATIONS OF CABLES
IEEE Std 525-1992 Annex A Sample calculations for cable pulling tensions
IEEE Std 422/2012
- Location
- Illinois
- Occupation
- retired electrician
And when you do the pulling calculations, remember that it is rare that the limiting factor is the actual pulling tension. Most often it is the "sidewall pressure" (the crushing force on the insulation as the conductors are pulled around bends). This pressure is a function of the pulling tension and the radius of the bend. Pulling force in pounds/bend radius in feet = sidewall pressure.
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