Question 1

Which frequency is a harmonic of 60 Hz?&#10;A) 10 Hz&#10;B) 30 Hz&#10;C) 90 Hz&#10;D) 180 Hz

Accepted Answer

A harmonic is a multiple of the fundamental frequency, which in this case is 60 Hz. Only option D, which is 3 times 60 Hz or 180 Hz, is a multiple and therefore a harmonic of 60 Hz.

Question 2

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

Accepted Answer

Large industrial establishments may have long distances between their power source and equipment, and higher voltages can reduce energy losses during transmission. Additionally, higher voltages can allow for more efficient use of equipment that requires high power consumption.

Question 3

It has been proven that currents as small as ____ through the heart, lungs, or brain can be fatal.&#10;A) 15 mA&#10;B) 50 mA&#10;C) 1 A&#10;D) 15 A

Accepted Answer

Currents as small as 50 mA (milliamperes) can disrupt the heart's electrical signals, potentially leading to fatal arrhythmias or cardiac arrest.

Question 4

Which type of ground-fault protection is generally used for three-wire, single-phase, and for three-phase installations?&#10;A) GFP&#10;B) GFCI&#10;C) fuse&#10;D) circuit breaker

Accepted Answer

The answer of Which type of ground-fault protection is generally...

Question 5

In a radial distribution system, the central station supplies power to the various ____.&#10;A) substations&#10;B) loops&#10;C) residential units&#10;D) industrial installations

Accepted Answer

In a radial distribution system, power flows from the central station to the various substations which then distribute power to the end users, such as residential units and industrial installations. Loops may exist within the system to increase reliability, but ultimately the power flow is radial from the central station to the substations. Therefore, choice A, substations, is the correct answer.

Question 6

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

Accepted Answer

A loop distribution system is designed to provide power in a loop or circular path, allowing for multiple paths for electricity to reach any given point, enhancing reliability and redundancy, rather than starting at a central station and supplying power to various substations in a linear fashion.

Question 7

Which NEC Article covers grounding locations and methods?&#10;A) Article 79&#10;B) Article 220&#10;C) Article 250&#10;D) Article 429

Accepted Answer

Article 250 covers grounding and bonding requirements, including grounding locations and methods.

Question 8

What does the abbreviation GFP stand for?&#10;A) Ground Fire Protection&#10;B) Ground Fire Prevention&#10;C) Ground Fault Protector&#10;D) Ground Fault Prevention

Accepted Answer

GFP stands for Ground Fault Protector, which is a device used to protect electrical circuits from ground faults.

Question 9

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

Accepted Answer

The primary purpose of grounding is to provide a path for electrical current to flow safely to the ground in case of a fault, thereby protecting people from electrical shock and equipment from damage.

Question 10

____ may be installed in a substation unit.&#10;A) Branch circuit conductors&#10;B) Isolation switches&#10;C) Main supply conductors&#10;D) Utility poles

Accepted Answer

Isolation switches may be installed in a substation unit to provide a means of disconnecting electrical equipment for maintenance or other purposes. Branch circuit conductors, main supply conductors, and utility poles are not typically installed within a substation unit.

Question 11

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.&#10;A) current&#10;B) voltage&#10;C) resistance&#10;D) reactance

Accepted Answer

The answer of If the ungrounded (hot) conductor comes in...

Question 12

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

Accepted Answer

The answer of Most single-phase systems are supplied from a...

Question 13

The effect of a harmonic on the current flowing in the supply conductors is approximately ____ percent.&#10;A) less than 1&#10;B) 3-5&#10;C) 10-20&#10;D) 80-90

Accepted Answer

The answer of The effect of a harmonic on the...

Question 14

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

Accepted Answer

The answer of The GFCI operates on the principle that...

Question 15

The effect of a harmonic on the current flowing in the neutral conductor is approximately ____ percent.&#10;A) less than one&#10;B) 3-5&#10;C) 50&#10;D) 90

Accepted Answer

The answer of The effect of a harmonic on the...

Deck 13: Electrical Distribution