Unassembled Trench Duct Components

Side rail assemblies are the heart of the railway system. They are furnished in 10 ft. (3 m) lengths and are positioned opposite each other by the use of spacer bars to form the various widths of trench duct. Side rails are coupled together and aligned by a wraparound coupler and aligner. Two screws in the coupler engage abutting side rails and assure continuity of ground.

The side rail assemblies have a full 1 in. (25 mm) of height adjust.

• 2.375–3.375 in. adjustability (60–86 mm) for 2.5 in. (64 mm) deep trench

• 3–4 in. adjustability (76–102 mm) for 3.25 in. (83 mm) deep trench

Side rail assemblies have a longitudinal slot along the full length of the extrusion to accept the cover plate hold-down screws. This permits cover plates to be placed anywhere along the run of trench without the restriction of fixed cover plate screw-hole locations. The bottom flange of this assembly forms a continuous weld tab along the entire length of the trench.

Side Rail Assembly

Most trench duct systems contain wiring for more than one type of service. Separation of the various services must be maintained.

A U-trough is used as the power compartment in bottomless trench ducts with cellular floor systems.

The Z-divider is used in bottom type trench systems.

U-Trough and Z-Dividers

A vertical elbow is a short section of trench duct with a riser welded to it. A vertical elbow can be mounted directly onto the side rail assemblies of the trench duct. The longitudinal screw slot in the side rail assemblies allows for tolerance, thereby enabling an exact positioning of the elbow.

The riser is manufactured to slip-fit on the elbow. One face of the riser is removable, allowing easy access for pulling wire and cable. A matching cabinet connector is manufactured to slip-fit on the riser and attach to the underside of a standard depth power panel tub.

A riser and cabinet connector, used as a power feeder, always uses a vertical elbow. However, a riser and cabinet connector are seldom used as a telephone feeder. Open telephone cabling from the vertical elbow to a terminal board is permissible and most often preferable.

Vertical Elbows and Risers with Cabinet Connectors

Cover plates are made of 0.25 in. (6 mm) nominal thickness steel, phosphatized with a baked enamel finish. Cover plate screw holes accommodate a 0.12 in. (3 mm) high pan-head screw for tile floor finishes, or flat head screws that finish flush for carpet installations. Screw holes in the opposite corners are threaded so that a 0.37 in. (10 mm) lifting bolt can be used for removing and replacing covers. Suction cups can also be used to remove covers.

Bottom plates are 5 ft. (1.5 m) long for ease of handling and are manufactured of 14-gauge galvanized steel. The width of the bottom plates is 3 in. (76 mm) wider than the cover plates.

Underwriters Laboratories permits 16.125 in. (409 mm) of free support span for cover plates. This is to control the amount of deflection and permanent set encountered in normal office floor loadings. The support post strip is available (where needed) to provide intermediate support in bottomless trench duct.

The support posts are mounted on a 5 ft. (1.5 m) channel and are adjustable to the underside of the cover plate. A nut locks the post firmly in place. The adjustable support posts are welded directly to the trench bottom plate in the factory-assembled bottom-type trench.

Support Post Strips

End closures, by design, close the end of a system run. They have a “0” length, thereby causing no field application problems related to length of runs. The end closure screws into the slot provided in the side rail assembly.

The slot has an upward and downward adjustment to correspond to the adjustment of the side rail assemblies.

End Closures

The space bar is used to establish exact width by placing two pins in either end of the bar to which engages the cover plate screw slot. After the side rail assemblies are adjusted to proper height, you can reverse the bar (with the pins up) to become a gauge for accurate partition adjustment.

Space Bar and Partition Height Adjustment Gauge

Use 10 ft. (3 m) long trench duct rail assemblies and other components listed below to field-assemble trench duct to fit specific job requirements. Side rail assemblies can be field cut to meet job conditions. Cover plates are shipped separately. Longitudinal slot for cover plate screws in side rail assembly permits random placement of cover plates. Cover plates are a standard 2 ft. (0.61 m) long and can be modified to suit odd lengths of trench duct runs. Spacer bars assure correct width and partition height adjustment. Illustrated installation instructions are included with all orders.

Railway Trench Duct

Railway Trench Duct Dimensions