Group T0A - Power circuits and hazards Flashcards
Power circuits and hazards: hazardous voltages, fuses and circuit breakers, grounding, electrical code compliance; Lightning protection; Battery safety
What is a safety hazard of a 12-volt storage battery?
Shorting the terminals can cause burns, fire, or an explosion
N/A
What health hazard is presented by electrical current flowing through the body?
All these choices are correct
1) It may cause injury by heating tissue;
2) it may disrupt the electrical functions of cells;
3) it may cause involuntary muscle contractions.
In the United States, what circuit does black wire insulation indicate in a three-wire 120 V cable?
Hot
N/A
What is the purpose of a fuse in an electrical circuit?
To remove power in case of overload
N/A
Why should a 5-ampere fuse never be replaced with a 20-ampere fuse?
Excessive current could cause a fire
N/A
What is a good way to guard against electrical shock at your station?
All these choices are correct
1) Use three-wire cords and plugs for all AC powered equipment;
2) connect all AC powered station equipment to a common safety ground;
3) install mechanical interlocks in high-voltage circuits.
Where should a lightning arrester be installed in a coaxial feed line?
On a grounded panel near where feed lines enter the building
N/A
Where should a fuse or circuit breaker be installed in a 120V AC power circuit?
In series with the hot conductor only
N/A
What should be done to all external ground rods or earth connections?
Bond them together with heavy wire or conductive strap
N/A
What hazard is caused by charging or discharging a battery too quickly?
Overheating or out-gassing
N/A
What hazard exists in a power supply immediately after turning it off?
Charge stored in filter capacitors
N/A
Which precautions should be taken when measuring high voltages with a voltmeter?
Ensure that the voltmeter and leads are rated for use at the voltages to be measured
N/A
