Deck 3: Feeder Bus System

Question 1

Describe the circuit-breaker cubicle.

Answer 1

The circuit-breaker cubicle consists of a cube-shaped steel housing. This housing can be attached to the lower side of the ventilated feeder duct. Two 225-ampere circuit breakers are provided in a single housing. Openings in the sides of the cubicle permit the attachment of a plug-in busway. This busway runs in opposite directions at right angles to the feeder. The circuit breakers protect the plug-in duct from overloads as required by 368.17(C). This section of the Code requires that a means such as chains, ropes, or sticks be provided so that the disconnecting means can be operated from the floor.

Question 2

Power can be tapped from the feeder busway at any opening.

A) joint
B) handhole
C) enclosure
D) tap

Answer 2

B

Question 3

The plug-in unit size of a bus plug is based on the .

A) switch ampere rating
B) protective devices rating
C) number of bus plugs required
D) number of end connections

Answer 3

A

Question 4

Straight sections, elbows, tees, and are standard components available for use so that ducts can be installed horizontally or vertically, edgewise or flat, and can meet any turn or elevation requirements.

A) busbars
B) covers
C) casings
D) crosses

Question 5

What is an additional role of connecting busways to enclosures such as unit substations?

Question 6

The plug-in busway is much like a extending through a complete load area.

A) switchboard
B) busbar
C) panelboard
D) circuit breaker

Question 7

Busways held up by cables must all be supported at intervals of ft or less.

A) three
B) four
C) five
D) six

Question 8

clamp hangers eliminate the drilling, cutting, or bending generally associated with hangers constructed on the job.

A) Prefabricated
B) Stenciled
C) Metal
D) Plastic

Question 9

The connection of the busway to enclosures such as unit substations is accomplished with .

A) ventilated steel halves
B) copper busbars
C) flanged end connections
D) No. 1 connections

Question 10

The busbars in the busway are coated with at each connection point since it is unequaled as an electrical conductor.

A) aluminum
B) copper
C) gold
D) silver

Question 11

What is the common name used by electricians for the assembly properly known as a busway?

A) bus duct
B) busbar
C) panelboard
D) switchboard

Question 12

How are plug-in busways suspended?

Question 13

What are the possible structures of plug-in busway fittings?

Question 14

cubicles are used to connect the No. 2 feeder busway to the 225-ampere, plug-in busway runs.

A) Circuit-breaker
B) Plug-in
C) Flanged end
D) End closer

Question 15

Tapoff openings every inches along the plug-in busway mean that there is always a convenient location to connect a machine.

A) four
B) five
C) nine
D) ten

Question 16

For feeder busway No. 2, rated at 1600 amperes, what is the current density in busbars with cross-sectional area of 394 square millimeters?

A) one ampere/mm2
B) two amperes/mm2
C) three amperes/mm² d. four amperes/mm²

Question 17

How are bus plugs selected?

Question 18

In feeder busway No. 2, snap-on covers insulate the bolted busbar sections.

A) polycarbonate
B) vinyl plastic
C) stainless steel
D) copper

Question 19

provide branch-circuit protection for each of the machines in the manufacturing area of the plant.

A) Steel halves
B) Bus plugs
C) End connections
D) Machine tools

Question 20

Feeder busway sections are available in standard ft lengths and in other lengths on special order.

A) 5
B) 10
C) 15
D) 20