Quote "The Inspector and Electrician looks at that conduit with 12 wires in where NEC says only 11 are allowed and says "NO!" The engineer looks at that conduit and says "Why does NEC say only 11 are allowed? Is it because of installation difficulty and risk of damage to the cables? Lets test the cables and see if any are damaged..." and so on."
Good Luck in your endeavours! Pull that with an inpector who was in the trade for 25 plus years and is showing up to your job at 4:30 on his 5th inspection of the day.
That is the attitude problem that seems to get us to where we are now. Rather than learn the codes and standards and learn from the seasoned veteran electricians, the engineer assumes superiority and questions the standards and practices by which they work.
The NEC is not a new document, it is the result of years and years of compiled knowledge. By no means perfect, but unless we are talking about a completely new technology and installation method or environment - it is pretty damn thorough and comprehensive.
As is relates to issues like conduit fill etc. The answer to the question "why this many or only this many" (aside from the reasions documented by others earlier in the post) is...because it has to be something.
It is a standardized number that is part of a greater set of standards. It may be 11 conductors's because if the NEC did not prescribe a limit, certain EC's would install 25, 30 or more.
