Back to Basics

Now that we have reviewed the components that make up a busway system, let’s put it all together. Consider this sample factory floor layout.

Sample Layout

Figure 12. Sample Factory Floor Layout

In this installation, there are feeder busway sections and plug-in busway sections. Elbows, tees and crosses are used to connect the busway sections. The busway supplies power for a motor control center, a lighting panelboard, a piece of machinery, and a pump motor.

Suppose the building owner wants to rearrange the locations of the loads. Most of the busway materials can be disassembled and rearranged with no loss.

Pencil Sketch

To lay out a busway system such as this one, all you need to do is make a simple pencil sketch with accurate dimensions. Indicate the lengths of busway required, and the locations and types of loads that will be supplied by the busway.

A pencil sketch for the busway system shown above is shown in Figure 13. From this sketch, you can price a busway installation. We will look at pricing in a moment.

Figure 13. Pencil Sketch for Sample Factory Floor Layout

This customer wants to run bus into a factory from outside, through an existing switchboard in the basement. The goal is to provide plug-ins along one wall of the three-story structure.

The customer has supplied distances between components and approximate run lengths. From this information, you can draw up an installation plan.

Here is one way you might draw up such a layout.

After completing the drawing, confer with the customer. Changes might be required. Verify this layout will meet the needs of the application before planning and pricing and order.

Formal Schematic

When you place the order, a more formal schematic will be created, containing accurately scaled dimensions. This schematic is used for customer approval and installation.

A formal schematic for the pencil sketch appears in Figure 14. Note that it has been reduced in size from the actual document that would be presented to the customer.

Figure 14. Formal Schematic for Sample Factory Floor Layout

Handling an Application Cost Efficiently

In addition to being able to prepare a pencil sketch, you need to understand a few other things to be able to cost-effectively assist a customer.

As we have already stated, busway replaces conduit and wire. Wire is rated in volts and amps. Like wire, busway is standardized to handle a maximum of 600 volts. Amp ratings range from 225 to 5,000, providing you with flexibility when working with a customer.

If possible, try to standardize a job on one amp rating. Replacement costs will be minimized if the customer wants to make changes to his layout in the future because more material can be reused.

Selecting plug-in devices is just like selecting individual safety switches and circuit breakers. Refer to your catalog for pricing information.

Pricing a Busway Installation

Now, let’s walk through how to price the sample layout in Figures 13 and 14. Total the number of each component in the layout. You will find you have:

142 feet of feeder busway
42 feet of plug-in busway
3 50-amp breaker plug-in devices
4 elbow sections
1 tee section
1 cross section
1 weatherhead
3 flanges
3 end closers

For the sake of the example, assume that the entire busway layout is rated at 600 amps. Suppose your price chart looked like this:

NOTE: Make sure that the total footage in your Bill Of Materials includes footage through all fittings, such as tap boxes, transformer throats and elbows.

The arithmetic is pretty straightforward:

(142 x $20) + (42 x $22) + (3 x $100) + (4 x $120) + $140 + $160 + $170 +
(3 x $130) + (3 x $20) = $5,464

This is the price for the materials specified in the sample factory layout in Figure 14. Note that this price does not include delivery or installation.