Deck 13: Electrical Distribution

Question 1

____ may be installed in a substation unit.

A) Branch circuit conductors
B) Isolation switches
C) Main supply conductors
D) Utility poles

Answer 1

B

Question 2

In a radial distribution system, the central station supplies power to the various ____.

A) substations
B) loops
C) residential units
D) industrial installations

Answer 2

A

Question 3

Which frequency is a harmonic of 60 Hz?

A) 10 Hz
B) 30 Hz
C) 90 Hz
D) 180 Hz

Answer 3

D

Question 4

The effect of a harmonic on the current flowing in the neutral conductor is approximately ____ percent.

A) 10
B) 3 to 5
C) 40 to 50
D) 90

Question 5

It has been proven that currents as small as ____ milliamperes through the heart, lungs, or brain can be fatal.

A) 15
B) 50
C) 5
D) 25

Question 6

If the ungrounded (hot) conductor comes in contact with a metal enclosure that is not grounded, a ____ will be present between the enclosure and the ground.

A) current
B) voltage
C) resistance
D) reactance

Question 7

The GFCI operates on the principle that an equal amount of current is flowing through the two wires.

Question 8

Most single-phase systems are supplied from a three-phase primary.

Question 9

A loop distribution system is an electrical transmission system that begins at a central station and supplies power to various substations.

Question 10

The purpose of grounding is to limit the magnitude of current surges.

Question 11

The effect of a harmonic on the current flowing in the supply conductors is approximately ____ percent.

A) 10
B) 3 to 5
C) 40 to 50
D) 90

Question 12

Which type of ground-fault protection is generally used for three-wire, single-phase, and for three-phase installations?

A) GFP
B) GFCI
C) fuse
D) circuit breaker

Question 13

What does the abbreviation GFP stand for?

A) Ground-Field Protector
B) Ground-Fire Prevention
C) Ground-Fault Protector
D) Ground-Flux Prevention

Question 14

Large industrial establishments may find it more economical to distribute power at voltages higher than 600 volts.

Question 15

Which NEC Article covers grounding locations and methods?

A) Article 79
B) Article 220
C) Article 250
D) Article 429