Chapter 13: Electrical Safety

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

• It may cause injury by heating tissue

• It may disrupt the electrical functions of cells

• It may cause involuntary muscle contractions

• All these choices are correct

In the United States, what circuit does black wire insulation indicate in a three-wire 120 V cable?

• Neutral

• Hot

• Equipment ground

• Black insulation is never used

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

• To prevent power supply ripple from damaging a component

• To remove power in case of overload

• To limit current to prevent shocks

• All these choices are correct

Why should a 5-ampere fuse never be replaced with a 20-ampere fuse?

• The larger fuse would be likely to blow because it is rated for higher current

• The power supply ripple would greatly increase

• Excessive current could cause a fire

• All these choices are correct

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

• Use three-wire cords and plugs for all AC powered equipment

• Connect all AC powered station equipment to a common safety ground

• Install mechanical interlocks in high-voltage circuits

• All these choices are correct

Where should a fuse or circuit breaker be installed in a 120V AC power circuit?

• In series with the hot conductor only

• In series with the hot and neutral conductors

• In parallel with the hot conductor only

• In parallel with the hot and neutral conductors

What hazard exists in a power supply immediately after turning it off?

• Circulating currents in the dc filter

• Leakage flux in the power transformer

• Voltage transients from kickback diodes

• Charge stored in filter capacitors

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

• Touching both terminals with the hands can cause electrical shock

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

• RF emissions from a nearby transmitter can cause the electrolyte to emit poison gas

• All these choices are correct

What hazard is caused by charging or discharging a battery too quickly?

• Overheating or out-gassing

• Excess output ripple

• Half-wave rectification

• Inverse memory effect