Chapter 2 - Mechanical Installation ing connecting the filter to the drive must be run in metallic conduit. Mounting the Drip Shield A drip shield is provided to prevent falling dirt and dripping fluids from entering the ventilation slots at the top of the drive enclosure. The drip shield snaps into place at the top of the enclosure. The enclosure is rated NEMA 1 only when the drip shield is installed. 14 ACS 300 User’s Manual