i think your answers might be in 501.1 thru 501.6
501.1 says if you want to use equipment in the classified area it has to be LISTED for that area...
Equipment listed and marked in accordance with 505.9(C)(2) for use in Class I, Zone 0, 1, or 2 locations shall be permitted in Class I, Division 2 locations for the same gas and with a suitable temperature class.
Exception: As modified by this article.
501.5 says you need sealing fittings...
501.5(B)(2) Class I, Division 2 Boundary. In each conduit run passing from a Class I, Division 2 location into an unclassified location. The sealing fitting shall be permitted on either side of the boundary of such location within 3.05 m (10 ft) of the boundary and shall be designed and installed so as to minimize the amount of gas or vapor within the Division 2 portion of the conduit from being communicated to the conduit beyond the seal.
there are some other things required in that section also
do you have the arlington explosionproof catalog? not sure what its called, maybe not even arlington, i'll get it from my rig and post the info, its from the 99 code but has code applications and materials, a good book to have around
