T0A – Power circuits and hazards: hazardous voltages, fuses and circuit breakers, grounding, electrical code compliance; Lightning protection; Battery safety 

- [[T0A01]] (B)
Which of the following is a safety hazard of a 12-volt storage battery? #card
	- A. Touching both terminals with the hands can cause electrical shock
	- B. Shorting the terminals can cause burns, fire, or an explosion
	- C. RF emissions from a nearby transmitter can cause the electrolyte to emit poison gas
	- D. All these choices are correct
--
- [[T0A02]] (D)
What health hazard is presented by electrical current flowing through the body? #card
	- 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 these choices are correct
--
- [[T0A03]] (B)
In the United States, what circuit does black wire insulation indicate in a three-wire 120 V cable? #card
	- A. Neutral
	- B. Hot
	- C. Equipment ground
	- D. Black insulation is never used
--
- [[T0A04]] (B)
What is the purpose of a fuse in an electrical circuit? #card
	- A. To prevent power supply ripple from damaging a component
	- B. To remove power in case of overload
	- C. To limit current to prevent shocks
	- D. All these choices are correct
--
- [[T0A05]] (C)
Why should a 5-ampere fuse never be replaced with a 20-ampere fuse? #card
	- A. The larger fuse would be likely to blow because it is rated for higher current
	- B. The power supply ripple would greatly increase
	- C. Excessive current could cause a fire
	- D. All these choices are correct
--
- [[T0A06]] (D)
What is a good way to guard against electrical shock at your station? #card
	- 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. Install mechanical interlocks in high-voltage circuits
	- D. All these choices are correct
--
- [[T0A07]] (D)
Where should a lightning arrester be installed in a coaxial feed line? #card
	- A. At the output connector of a transceiver
	- B. At the antenna feed point
	- C. At the ac power service panel
	- D. On a grounded panel near where feed lines enter the building
--
- [[T0A08]] (A)
Where should a fuse or circuit breaker be installed in a 120V AC power circuit? #card
	- A. In series with the hot conductor only
	- B. In series with the hot and neutral conductors
	- C. In parallel with the hot conductor only
	- D. In parallel with the hot and neutral conductors
--
- [[T0A09]] (C)
What should be done to all external ground rods or earth connections? #card
	- A. Waterproof them with silicone caulk or electrical tape
	- B. Keep them as far apart as possible
	- C. Bond them together with heavy wire or conductive strap
	- D. Tune them for resonance on the lowest frequency of operation
--
- [[T0A10]] (A)
What hazard is caused by charging or discharging a battery too quickly? #card
	- A. Overheating or out-gassing
	- B. Excess output ripple
	- C. Half-wave rectification
	- D. Inverse memory effect
--
- [[T0A11]] (D)
What hazard exists in a power supply immediately after turning it off? #card
	- A. Circulating currents in the dc filter
	- B. Leakage flux in the power transformer
	- C. Voltage transients from kickback diodes
	- D. Charge stored in filter capacitors
--
- [[T0A12]] (B)
Which of the following precautions should be taken when measuring high voltages with a voltmeter? #card
	- A. Ensure that the voltmeter has very low impedance
	- B. Ensure that the voltmeter and leads are rated for use at the voltages to be measured
	- C. Ensure that the circuit is grounded through the voltmeter
	- D. Ensure that the voltmeter is set to the correct frequency