SUBELEMENT T0 – Electrical safety: AC and DC power circuits; antenna installation; RF hazards – [3 Exam Questions - 3 Groups]

Question 1

T0A01 (B)

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

Answer 1

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

Question 2

T0A02 (D)

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

Answer 2

A. It may cause injury by heating tissue
B. It may disrupt the electrical functions of cells
C. It may cause involuntary muscle contractions
D. All of these choices are correct

Question 3

T0A03 (C)

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

Answer 3

C. Equipment ground

Question 4

T0A04 (B)

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

Answer 4

B. To interrupt power in case of overload

Question 5

T0A05 (C)

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

Answer 5

C. Excessive current could cause a fire

Question 6

T0A06 (D)

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

Answer 6

A. Use three-wire cords and plugs for all AC powered equipment
B. Connect all AC powered station equipment to a common safety ground
C. Use a circuit protected by a ground-fault interrupter
D. All of these choices are correct

Question 7

T0A07 (D)
Which of these precautions should be taken when installing devices for lightning protection in a coaxial cable feed line?

Answer 7

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

Question 8

T0A08 (A)

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

Answer 8

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

Question 9

T0A09 (C)

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

Answer 9

C. Bond them together with heavy wire or conductive strap

Question 10

T0A10 (A)

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

Answer 10

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

Question 11

T0A11 (D)

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

Answer 11

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

Question 12

T0B01 (C)

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

Answer 12

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

Question 13

T0B02 (C)

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

Answer 13

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

Question 14

T0B03 (D)

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

Answer 14

D. Never

Question 15

T0B04 (C)

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

Answer 15

C. Look for and stay clear of any overhead electrical wires

Question 16

T0B05 (C)

What is the purpose of a gin pole?

Answer 16

C. To lift tower sections or antennas

Question 17

T0B06 (D)

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

Answer 17

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

Question 18

T0B07 (C)

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

Answer 18

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

Question 19

T0B08 (C)

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

Answer 19

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

Question 20

T0B09 (C)

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

Answer 20

C. The antenna could contact high-voltage power lines

Question 21

T0B10 (C)

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

Answer 21

C. Sharp bends must be avoided

Question 22

T0B11 (B)

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

Answer 22

B. Local electrical codes

Question 23

T0B12 (C)

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

Answer 23

C. Ensure that connections are short and direct

Question 24

T0B13 (B)

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

Answer 24

B. Prevent loosening of the guy line from vibration

Question 25

T0C01 (D)

What type of radiation are VHF and UHF radio signals?

Answer 25

D. Non-ionizing radiation

Question 26

T0C02 (B)

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

Answer 26

B. 50 MHz

Question 27

T0C03 (C)
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

C. 50 watts PEP at the antenna

Question 28

T0C04 (D)

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

Answer 28

A. Frequency and power level of the RF field
B. Distance from the antenna to a person
C. Radiation pattern of the antenna
D. All of these choices are correct

Question 29

T0C05 (D)

Why do exposure limits vary with frequency?

Answer 29

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

Question 30

T0C06 (D)

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

Answer 30

A. By calculation based on FCC OET Bulletin 65
B. By calculation based on computer modeling
C. By measurement of field strength using calibrated equipment
D. All of these choices are correct

Question 31

T0C07 (B)

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

Answer 31

B. They might receive a painful RF burn

Question 32

T0C08 (A)
Which of the following actions might amateur operators take to prevent exposure to RF radiation in excess of FCC-supplied limits?

Answer 32

A. Relocate antennas

Question 33

T0C09 (B)

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

Answer 33

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

Question 34

T0C10 (A)

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

Answer 34

A. It affects the average exposure of people to radiation

Question 35

T0C11 (C)

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

Answer 35

C. The percentage of time that a transmitter is transmitting

Question 36

T0C12 (A)

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

Answer 36

A. RF radiation does not have sufficient energy to cause genetic damage

Question 37

T0C13 (C)
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

C. 2 times as much