I-Line Layout and Measurement

From the bid documents, specifications, and/or factory drawings, the following information is known:

• Busway is to be 1600 A, 3Ø4W, 50% GND, aluminum feeder busway. Width is determined to be 8.84 in. (225 mm).

• Switchboard is 7 ft x 7.5 in. (213 cm x 191 mm) high, 3 ft (91 cm) wide, and 2 ft (61 cm) deep. Busway connection to be in top center.

• Motor control center is 7 ft x 7.5 in. (213 cm x 191 mm) high with a 1 ft (30 cm) additional height pull box for busway connection; 20 in. (508 mm) wide; 20 in. (508 mm) deep. Busway connection is in top center.

• Bottom of busway (BOB.) to be installed 16 ft (488 cm) above finished floor (AFF) unless obstructed.

Physical Size of Busway Housing

1. Determine the physical size of the busway housing.

   This information lets you know how far to stay away from obstructions. In our example, Physical Size of Busway Housing, the busway is 8.84 in. (225 mm) wide and 5.88 in. (149 mm) high (9 in. x 6 in. (229 mm x 152 mm) nominal).

2. Review the area where the busway could be installed (if not already specified).

   NOTE: Special conditions such as building expansion joints, steel changes, HVAC equipment, and plumbing lines.

3. Measure all dimensions from fixed points.

   Measure dimensions such as columns, walls, or other building structures. Try to leave at least 4 in. (102 mm) between the busway and any obstructions. Plan View Switchboard, MCC, and Obstructions shows the switchboard and MCC locations, the obstructions, and the dimensions to fixed points.

4. Start dimensional layout from the fixed end.

   Sketch the proposed busway routing, noting elevations and obstructions (see Proposed Busway Layout).

5. Route the busway above the bottom of the building steel, unless specified.

   For industrial applications, this protects the busway from damage by forklifts, cranes, etc. The busway must be supported by drop rods or from below. Do not route busway where it cannot be adequately supported.

6. When selecting the elevation for plug-in busway, remember that overcurrent devices (plug-in units) can require different mounting clearances.

   Referring to the sample busway layout (see Proposed Busway Layout), enough information is known to tabulate the amount of busway footage needed and the required fittings (e.g., flanged ends, elbows). A copy of the figure could help your local representative with pricing your job and also could be forwarded to the factory to aid in preparation of approval or record drawings.

Plan View Switchboard, MCC, and Obstructions

Proposed Busway Layout