Deck 15: Electrical Services

Question 1

Some fuses are designed to delay for a period of time before they open. These fuses are often referred to as time-delay fuses or ____ fuses.

A) breaker
B) measured-response
C) slow-blow
D) quick-start

Answer 1

C

Question 2

The type of three-phase service is determined by the type of secondary transformer connection supplied by the power company.

Answer 2

True

Question 3

The wire size is determined by the ____ rating of the circuit.

A) voltage
B) ampere
C) reactance
D) turns ratio

Answer 3

B

Question 4

When aluminum is used for the bus material, an antioxidant compound should be used to prevent ____.

A) splitting
B) corrosion
C) melting
D) sparking

Question 5

Standard size circuit breakers are approximately ____ inch(es) in width.

A) 0.5
B) 1
C) 2
D) 4

Question 6

The fall-of-potential test requires the use of a ground resistance meter.

Question 7

There are three main tests used to measure ground resistance. One of these is the ____.

A) Wenner five-point test
B) Hall generator test
C) four-point fall-of-potential test
D) clamp-on ground resistance test

Question 8

When making a 240-V single-phase connection with neutral, the ____ conductors are connected to the poles of the circuit breaker.

A) white and bare
B) black and red
C) black and white
D) red and white

Question 9

Many circuit breaker panels are designed to employ half-size circuit breakers.

Question 10

Table 14-2
Assume a branch circuit rated at 90 A is to be installed using copper wire with type THW insulation. Use the accompanying table to determine what size conductor should be used for this installation.

A) #2 AWG copper conductor
B) #3 AWG copper conductor
C) #4 AWG copper conductor
D) #6 AWG copper conductor

Question 11

Fuses are connected in series with the load.

Question 12

The three-phase three-wire system is made by connecting the ____ windings of a three-phase transformer bank in ____ and connecting the three lines to a three-phase panel.

A) secondary; either wye or delta
B) secondary; wye
C) primary; delta
D) primary; wye

Question 13

Table 14-2
A branch circuit rated at 150 A is to be installed using aluminum wire with type THHW insulation. Use the accompanying table to determine what size conductor should be used for this installation.

A) #1/0 AWG conductor
B) #2/0 AWG conductor
C) #3/0 AWG conductor
D) #4/0 AWG conductor

Question 14

Proper grounding helps protect against ____ currents, electrical noise, and lightning strikes.

A) continuous
B) transient
C) transformed
D) closed loop

Question 15

____-pole circuit breakers are used to connect three-phase circuits.

A) Single
B) Double
C) Three
D) Variable

Question 16

The clamp-on ground resistance test has several advantages over the three-point fall-of-potential test.

Question 17

In theory, the system ground is considered to have a resistance of ____.

A) zero
B) one
C) ten
D) infinity

Question 18

Circuit breakers that operate by heat are known as ____ circuit breakers.

A) fuse
B) magnetic
C) electrical
D) thermal

Question 19

The three-phase four-wire high-leg connection is made by connecting the secondary windings of a three-phase transformer bank in delta or open delta and center tapping one of the transformer secondaries to provide a(n) ____ conductor.

A) ungrounded
B) bussed
C) neutral
D) hot

Question 20

In a single-phase service, ____ V is available from the center tap to either end of the secondary winding.

A) 60
B) 100
C) 120
D) 240