Code of the day protecting nm cable in conduit

[Jpflex]

Regarding the code of the day, the NEC book to my knowledge failed to address calculations for max conduit fill when nm cable is ran inside conduit. Obviously the nm cable sheathing takes up more space than the insulated conductors and shouldn't be calculated with only conductor diameter as typical.


However one book I came across said to measure the diameter of the nm cable jacket sheath and treat this as one conductor (percent fill table) when determining max conduit fill for nm cables. Is this correct?

 

[augie47]

The book is correct, If you are installing a cable such as NM in conduit, Table 1 Chapter 9 addresses the method used to determine fill.
If you are simply sleeving the NM to protect it from damage I know of no restriction.