I am more-or-less endorsing the previous answer but trying to be more specific. Each raceway wall penetration must be sealed within 18 inches of the boundary as required in Section 501.15(A)(4). Neither of the Exceptions applies to the installation as you have described it. This can be difficult since no union, coupling, box, or other fitting except for a listed explosionproof reducer installed at the conduit seal is permitted between the seal and the boundary....
Is it necessary to have a seal off at each wall pack?
the requirement for boundary seal is 10' from the boundary, correct? Not 18"? Must be the first fitting on either side.I am more-or-less endorsing the previous answer but trying to be more specific. Each raceway wall penetration must be sealed within 18 inches of the boundary as required in Section 501.15(A)(4). Neither of the Exceptions applies to the installation as you have described it. This can be difficult since no union, coupling, box, or other fitting except for a listed explosionproof reducer installed at the conduit seal is permitted between the seal and the boundary.