Unassembled Rail-Way Trench Duct Specifications

All components of the trench header assembly shall be manufactured in accordance with the standards of Underwriters Laboratories, Inc.

Cover plates for trench duct shall be of nominal 0.25 in. (6 mm) thick steel sheet, roller leveled after being sheared to size.

The tile trim strip shall be of neutral gray vinyl and be designed so that either a 0.06 in. (2 mm) or 0.12 in. (3 mm) wide trim edge is available.

The side rail assemblies shall be furnished in 10 ft. maximum lengths. Height adjustment shall be from:

• .37–3.37 in. (61–86 mm) for a 2.25 in. (64 mm fill)

• 3–4 in. (76–102 mm) for a 3.25 in. (83 mm) fill

  Assemblies shall be adjustable prior to the installation of the cover plates. The inside dimension of the trench shall not be more than 1.87 in. (48 mm) less than the cover plate width. Assemblies shall be non-adjustable after the pour to assure rigidity of installation.

The side rail assemblies shall utilize a continuous screw slot to receive the cover plates in random position anywhere along the trench duct run.

The power compartment (U-trough) shall be 3.25 in. (89 mm) wide. The access hole into the power cell shall be field-drilled. The side partitions of the U-trough shall be adjustable to provide a cover plate support. Installer shall adjust the barriers and weld them into permanent position with a 0.50 in. (13 mm) long weld approximately 2 ft. (610 mm) on center. Extruded plastic sound dampeners shall be provided on the top of the adjustable barriers at approximately 20 in. (508 mm) intervals. Adjustment and welding shall be done prior to placement of the covers to provide support during construction.

Any compartment greater than 16 in. (407 mm) wide shall have additional cover plate support.

The cover plates shall be a maximum of 2 ft. (610 mm) long, and the abutting ends shall be gasketed. Cover plates shall be held in place by screws. The holes in the cover plate shall accept 0.12 in. (3 mm) high pan-head screws if floor tile is used or flat head screws that shall finish flush with the cover plate if carpet is used. Cover plates shall be shipped separately to the job site.

Vertical elbows, where required, shall be an integral part of a cover plate. Tees, horizontal elbows, crosses, offsets, cover plate tape, grommets, end closures, risers and connectors shall be furnished to complete the installation as specified.