The NEC is only as "national" as we choose to make it, when we adopt it into our local regulations. Just because the publisher calls it "National" doesn't make it so!
The NEC has prooven itself so well over the years that is has become universally respected- if not always adopted verbatum. Of course, there have always been differing schools of thought, as well as regional differences.
Despite warm and suzy sentiments about the NEC being a "consensus" standard, the only parties with a real voice are those who are able to attend national conventions. Some cynics have claimed that this gives an advantage to manufacturers, and other large organisations, that have the time, personnel, and money to spend the thousands of dollars necessary to attend one of these conferences.
As the NEC has expanded over the years, more provisions are called into question. The entire AFCI debate has been the most passionate one. Many, in every aspect of the trade, have qualms about the way the code has addressed the issue, the way it has been put into practice, and the equipment required.
So I'm not surprised that there has been widespread disagreement over the AFCI part of the code. For tose who remember the introduction of the GFCI, it was not accepted- indeed faced fierce opposition- until there were literally decades of documented use. During these decades, there were many, many improvements made, to address flaws that were uncovered. Contrast this to the AFCI experience, which has seen the code repeatedly mandate the future use of things not yet manufactured- let alone prooven.
