Sub-Element T0 Electrical Safety: AC & DC power circuits, antenna installation, RF hazards [3 Exam Questions]

Question 1

Which of the following is a safety hazard of a 12-volt storage battery?

Answer 1

Shorting the terminals can cause burns, fire, or an explosion

Question 2

What health hazard is presented by electrical current flowing through the body?

Answer 2

All of these choices are correct

Question 3

In the United States, what is connected to the green wire in a three-wire electrical AC plug?

Answer 3

Equipment ground

Question 4

What is the purpose of a fuse in an electrical circuit?

Answer 4

To interrupt power in case of overload

Question 5

Why is it unwise to install a 20-ampere fuse in the place of a 5-ampere fuse?

Answer 5

Excessive current could cause a fire

Question 6

What is a good way to guard against electrical shock at your station?

Answer 6

All of these choices are correct

Question 7

Which of these precautions should be taken when installing devices for lightning protection in a coaxial cable feed line?

Answer 7

Mount all of the protectors on a metal plate that is in turn connected to an external ground rod

Question 8

What safety equipment should always be included in home-built equipment that is powered from 120V AC power circuits?

Answer 8

A fuse or circuit breaker in series with the AC hot conductor

Question 9

What should be done to all external ground rods or earth connections?

Answer 9

Bond them together with heavy wire or conductive strap

Question 10

What can happen if a lead-acid storage battery is charged or discharged too quickly?

Answer 10

The battery could overheat, give off flammable gas, or explode

Question 11

What kind of hazard might exist in a power supply when it is turned off and disconnected?

Answer 11

You might receive an electric shock from the charge stored in large capacitors

Question 12

When should members of a tower work team wear a hard hat and safety glasses?

Answer 12

At all times when any work is being done on the tower

Question 13

What is a good precaution to observe before climbing an antenna tower?

Answer 13

Put on a carefully inspected climbing harness (fall arrester) and safety glasses

Question 14

Under what circumstances is it safe to climb a tower without a helper or observer?

Answer 14

Never

Question 15

Which of the following is an important safety precaution to observe when putting up an antenna tower?

Answer 15

Look for and stay clear of any overhead electrical wires

Question 16

What is the purpose of a gin pole?

Answer 16

To lift tower sections or antennas

Question 17

What is the minimum safe distance from a power line to allow when installing an antenna?

Answer 17

Enough so that if the antenna falls unexpectedly, no part of it can come closer than 10 feet to the power wires

Question 18

Which of the following is an important safety rule to remember when using a crank-up tower?

Answer 18

This type of tower must not be climbed unless retracted or mechanical safety locking devices have been installed

Question 19

What is considered to be a proper grounding method for a tower?

Answer 19

Separate eight-foot long ground rods for each tower leg, bonded to the tower and each other

Question 20

Why should you avoid attaching an antenna to a utility pole?

Answer 20

The antenna could contact high-voltage power lines

Question 21

Which of the following is true when installing grounding conductors used for lightning protection?

Answer 21

Sharp bends must be avoided

Question 22

Which of the following establishes grounding requirements for an amateur radio tower or antenna?

Answer 22

Local electrical codes

Question 23

Which of the following is good practice when installing ground wires on a tower for lightning protection?

Answer 23

Ensure that connections are short and direct

Question 24

What is the purpose of a safety wire through a turnbuckle used to tension guy lines?

Answer 24

Prevent loosening of the guy line from vibration

Question 25

What type of radiation are VHF and UHF radio signals?

Answer 25

Non-ionizing radiation

Question 26

Which of the following frequencies has the lowest value for Maximum Permissible Exposure limit?

Answer 26

50 MHz

Question 27

What is the maximum power level that an amateur radio station may use at VHF frequencies before an RF exposure evaluation is required?

Answer 27

50 watts PEP at the antenna

Question 28

What factors affect the RF exposure of people near an amateur station antenna?

Answer 28

All of these choices are correct

Question 29

Why do exposure limits vary with frequency?

Answer 29

The human body absorbs more RF energy at some frequencies than at others

Question 30

Which of the following is an acceptable method to determine that your station complies with FCC RF exposure regulations?

Answer 30

All of these choices are correct

Question 31

What could happen if a person accidentally touched your antenna while you were transmitting?

Answer 31

They might receive a painful RF burn

Question 32

Which of the following actions might amateur operators take to prevent exposure to RF radiation in excess of FCC-supplied limits?

Answer 32

Relocate antennas

Question 33

How can you make sure your station stays in compliance with RF safety regulations?

Answer 33

By re-evaluating the station whenever an item of equipment is changed

Question 34

Why is duty cycle one of the factors used to determine safe RF radiation exposure levels?

Answer 34

It affects the average exposure of people to radiation

Question 35

What is the definition of duty cycle during the averaging time for RF exposure?

Answer 35

The percentage of time that a transmitter is transmitting

Question 36

How does RF radiation differ from ionizing radiation (radioactivity)?

Answer 36

RF radiation does not have sufficient energy to cause genetic damage

Question 37

If the averaging time for exposure is 6 minutes, how much power density is permitted if the signal is present for 3 minutes and absent for 3 minutes rather than being present for the entire 6 minutes?

Answer 37

2 times as much