Inner duct Installation FREE cabling and networking Helpdesk
 Question by Don Bittle posted 29 Dec 2005
 Inner duct Installation
I am administering a contract that requires the installation of three SDR 11 inner duct in a 4-inch conduit. The contractor is unable to pull the three duct due to what appears to be the stiffness of the inner duct. Is there a standard or rule-of-thumb for number of innerduct persize of conduit. Could temperature, it's in the 50's, be a factor?
 Answer by Dmitri Abaimov posted 30 Dec 2005
Dear Don,

You did not indicate the diameter of the SDR11 pipe, but it does look like you may already be pushing it if the trade size of it is 1-1/2". Besides, the conduit is probably not laying perfectly straight in which case the fill ratio would have to be decreased. Also, solid wall innerducts are obviously much more demanding it terms of geometry of the conduit run and, as you pointed out, the temperature may also be an issue. I don't think 50 degrees Fahrenheit is an issue but lower temperature may be. See this link here for more info on innerducts and a handy innerduct calculator

Dmitri Abaimov, RCDD

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