An unprotected location exposed to the weather is by Article 100 defined as a wet location. 300.7 requires conduit sealing in dry locations where subject to temperature changes. 310.8 (C) requires all conductors installed in wet locations to be of a type listed for use in wet locations (or W in the insulation designation), or have a moisture-impervious metal-sheath (MI cable).
I don't see NM cable meeting these requirements. The letter of the code would require any conductor installed outdoors to be water proof (W). The AHJ could NOT, by building code, allow site specific circumstances and his considerable experience to "bend" the rules. He would be sticking his neck out, although it is done every day.
Section 109 of the IBC: "Inspections presuming to give authority to violate or cancel the provisions of this code or of other ordinances of the jurisdiction shall not be valid." The IBC references the NEC through the IEC.
So, you would take your chances if you don't use the proper wire type for the circumstances. You wouldn't use 30 volt wire for line voltages would you? It works for a while, then SNAP, CRACKLE, POP. Or, how about using #12 for a 30 amp load? It probably won't ever fail, but if it does, YOU will be liable!
Earl
