Sub-Element T0 Electrical Safety: AC & DC power circuits, antenna installation, RF hazards [3 Exam Questions] Flashcards
Which of the following is a safety hazard of a 12-volt storage battery?
Shorting the terminals can cause burns, fire, or an explosion
What health hazard is presented by electrical current flowing through the body?
All of these choices are correct
In the United States, what is connected to the green wire in a three-wire electrical AC plug?
Equipment ground
What is the purpose of a fuse in an electrical circuit?
To interrupt power in case of overload
Why is it unwise to install a 20-ampere fuse in the place of a 5-ampere fuse?
Excessive current could cause a fire
What is a good way to guard against electrical shock at your station?
All of these choices are correct
Which of these precautions should be taken when installing devices for lightning protection in a coaxial cable feed line?
Mount all of the protectors on a metal plate that is in turn connected to an external ground rod
What safety equipment should always be included in home-built equipment that is powered from 120V AC power circuits?
A fuse or circuit breaker in series with the AC hot conductor
What should be done to all external ground rods or earth connections?
Bond them together with heavy wire or conductive strap
What can happen if a lead-acid storage battery is charged or discharged too quickly?
The battery could overheat, give off flammable gas, or explode
What kind of hazard might exist in a power supply when it is turned off and disconnected?
You might receive an electric shock from the charge stored in large capacitors
When should members of a tower work team wear a hard hat and safety glasses?
At all times when any work is being done on the tower
What is a good precaution to observe before climbing an antenna tower?
Put on a carefully inspected climbing harness (fall arrester) and safety glasses
Under what circumstances is it safe to climb a tower without a helper or observer?
Never
Which of the following is an important safety precaution to observe when putting up an antenna tower?
Look for and stay clear of any overhead electrical wires
What is the purpose of a gin pole?
To lift tower sections or antennas
What is the minimum safe distance from a power line to allow when installing an antenna?
Enough so that if the antenna falls unexpectedly, no part of it can come closer than 10 feet to the power wires
Which of the following is an important safety rule to remember when using a crank-up tower?
This type of tower must not be climbed unless retracted or mechanical safety locking devices have been installed
What is considered to be a proper grounding method for a tower?
Separate eight-foot long ground rods for each tower leg, bonded to the tower and each other
Why should you avoid attaching an antenna to a utility pole?
The antenna could contact high-voltage power lines
Which of the following is true when installing grounding conductors used for lightning protection?
Sharp bends must be avoided
Which of the following establishes grounding requirements for an amateur radio tower or antenna?
Local electrical codes
Which of the following is good practice when installing ground wires on a tower for lightning protection?
Ensure that connections are short and direct
What is the purpose of a safety wire through a turnbuckle used to tension guy lines?
Prevent loosening of the guy line from vibration
What type of radiation are VHF and UHF radio signals?
Non-ionizing radiation
Which of the following frequencies has the lowest value for Maximum Permissible Exposure limit?
50 MHz
What is the maximum power level that an amateur radio station may use at VHF frequencies before an RF exposure evaluation is required?
50 watts PEP at the antenna
What factors affect the RF exposure of people near an amateur station antenna?
All of these choices are correct
Why do exposure limits vary with frequency?
The human body absorbs more RF energy at some frequencies than at others
Which of the following is an acceptable method to determine that your station complies with FCC RF exposure regulations?
All of these choices are correct
What could happen if a person accidentally touched your antenna while you were transmitting?
They might receive a painful RF burn
Which of the following actions might amateur operators take to prevent exposure to RF radiation in excess of FCC-supplied limits?
Relocate antennas
How can you make sure your station stays in compliance with RF safety regulations?
By re-evaluating the station whenever an item of equipment is changed
Why is duty cycle one of the factors used to determine safe RF radiation exposure levels?
It affects the average exposure of people to radiation
What is the definition of duty cycle during the averaging time for RF exposure?
The percentage of time that a transmitter is transmitting
How does RF radiation differ from ionizing radiation (radioactivity)?
RF radiation does not have sufficient energy to cause genetic damage
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?
2 times as much
