Need some help here. We have a duct bank running from an unclassified area to classified. (Class1 Div 2). Entry into duct bank is via cable tray on both ends. Do we need seals at both ends of run emerging from the duct bank? Or only the end were conduits emerge to unclassified area within 5' of the ground? I've been through 501 but am still a little confused. Thanks.