2"pvc capacity for cat5e in any grouping

Cabling-Design.com FREE cabling and networking Helpdesk
 Question by Joseph cable posted 20 Jul 2012
 2"pvc capacity for cat5e in any grouping
Existing pathway is composed of 2"pvc conduit transferring (dumping) into a 4" wide Walker duct(infloor trench style duct((conduit spills into ducting blindly at unkownpoint of the run that is no longer accessible))) total distance of 175'. Need to provide 4 standard Cat5e cables per desk (8desks= 8desks x4cables x4pr= 132pairs ) as a 4port outlet at one end and terminate to patch panel on other. As conduit is old and concerns have been raised about capacity as well as strict pulling time line of 5hrs as job requires "Downing of site"--is it best to pull 32 individual cables or to pull in 6x25pr cat5e punch to a 66block then go individual cables to each desk once outside the conduit???
 Answer by Dmitri Abaimov posted 20 Jul 2012
Dear Joseph,

Do you have just one 2" PVC pipe and need to pull 32 x CAT5e cables? That's just not going to work! You may be able to jam this many into a very short stub of a 2" pipe but that's not really a pathway, I'm assuming you need to go some considerable length, so that's not going to work. This is not even talking about any turns in the pipe, just a straight run will not work.

25pair CAT5 cables are rather rigid, they do not pull easy even though they may get you more pairs in a given crossection or a *straight* run. Since you need to come out of the PVC and into a floor duct at an unknown and inaccessible point, you need your cables to be as flexible as you can get so they can conform to an unknown radius turns better.

Do you have to pull all cables in the same direction after you passed this intersection of 2" and 4" duct? Or are the desks all around that spot?

Anyhow, suppose I did not understand you correctly and you have more than one 2" PVC pipe. Still, you are merging from a very thin pipe into an unknown fill ducts at an unknown and inaccessible point - this just begs for trouble. What is in the duct, anyhow? Is there an existing abandoned cabling you can pull out from that duct (charge the customer for it) and while at it, investigate the fill/layout of the duct, find any access points still available, learn the duct distribution to a degree that would make you more comfortable with adding new cable to it later.

Is the furniture sitting ontop of the duct? Where are you going to keep you intermediate connection points (those 66-type blocks)?

Given the unknowns of the duct, I would not commit to 5hr downtime deadline either.

Our ancient Helpdesk system does not allow adding text to the original question. If you have any additional info you'd like to share, just post another question referencing this one and we'll pick it up from there.

Dmitri Abaimov, RCDD

Click here to see the expert's profile
Back to the current page of questions | Back to all the questions
Back to Cabling-Design.com HELPDESK | Ask your question
Residential Cabling Guide

Home Cabling Guide

Finally, an instantly downloadable book that saves you thousands in home improvement dollars! Enjoy living in 21st century technology-advanced home while increasing its selling value and competitive advantage on the real estate market. Whether your cabling is for home office or high-tech leisure, you can wire your home yourself or learn "wirish" to speak with your cabling contractors in their language!

Learn more ...