I have questions concerning 513.8 and 501.15(A)(4) exception1 . I found an older post and it appears that 513.8(B) trumps the exception . Just wandering if that is still standard procedure or if I missed something . would appreciate any help . Thanks.
The "trump card" is Section 510.2. Articles 511 through 517 override the general rules of Articles 500 through 504 when the installation is within the scope of Articles 511 to 517.
This is an unfortunate case where two Technical Committees (TCs) may not entirely see eye-to-eye and the coordinator in this case is not the NEC Technical Coordinating Committee (TCC) but the NFPA Standards Council (SC). Again unfortunately, the SC often does not always have the integral technical competence to judge the conflict without a long drawn out process – these are some VERY smart folks that just don’t usually have the requisite experience for such judgment.
A large portion of Article 513 was originally extracted from NFPA 409-2011, Standard on Aircraft Hangars. Code Making Panel 14 (CMP14) usually considers grade the boundary and the underground unclassified. Several of the TCs that provide the extracted material for Articles 511-517 have a different opinion.
Personally, using the last sentence in Section 510.2, if I were the AHJ, I’d permit your installation as described. But in the interest of full disclosure, I’m heavily biased toward CMP14.
Actually 513.8(B) says there is no classified location boundary at hangar floor since the raceway ?? shall be considered to be within the Class I location above the floor ?? But 513.8(A) says underground wiring shall be treated as a Division 1 location, whether it truly is or not.513.8 (B) would still be the determining article in his application inside an aircraft hanger, the article states that regardless of the point at which the raceway descends below or rises above the floor, it shall be considered a C1 location. Am I correct with this line of thought?
Why would the AHJ override an article that appears somewhat strait forward as to what the NEC requires?