Questions And 100% Correct Answers (Verified Answers)
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1. Which of the following is the primary function of a circuit breaker?
a) To increase voltage in a circuit
b) To convert AC to DC
c) To protect electrical circuits from overcurrent
d) To measure current flow
Circuit breakers automatically interrupt current flow when it
exceeds a safe level, preventing damage and fire hazards.
2. What is the purpose of a grounding conductor in an electrical
system?
a) To carry normal operating current
b) To increase circuit resistance
c) To provide a safe path for fault current
d) To reduce voltage
A grounding conductor ensures that fault current safely travels to
the earth, minimizing shock hazards.
3. Which type of wiring method is typically used for commercial
buildings?
a) NM cable (Romex)
b) Conduit wiring
c) Knob-and-tube
, d) Flexible cords
Conduit wiring protects wires in commercial settings and allows for
future modifications.
4. The unit of electrical resistance is:
a) Ampere
b) Ohm
c) Volt
d) Watt
Resistance is measured in ohms (Ω), which quantifies how much a
material opposes current flow.
6. In a single-phase AC system, the voltage between the neutral and
hot wire is: a) Zero
b) 120 volts (in standard US residential systems)
c) 240 volts
d) 480 volts
Residential single-phase systems typically provide 120 V between
hot and neutral and 240 V across two hots.
7. What does the term "short circuit" refer to?
a) High voltage drop across a load
b) A low-resistance connection bypassing the load
c) Normal current flow in a circuit
d) A device that increases current
A short circuit occurs when current bypasses the designed path,
potentially causing overheating or fire.
8. Which device is used to step down voltage in an electrical system?
a) Generator
, b) Transformer
c) Capacitor
d) Circuit breaker
A transformer reduces voltage from high to low levels while
maintaining power.
9. Which instrument is used to measure electrical current?
a) Voltmeter
b) Ammeter
c) Ohmmeter
d) Wattmeter
Ammeters measure current flow in amperes and must be connected
in series with the circuit.
5. Which color is commonly used for grounding conductors in the
US?
a) Black
b) Red
c) Green
d) White
Green (or bare copper) identifies grounding conductors according
to the NEC.
10. What is the main advantage of using a three-phase electrical
system?
a) It requires fewer wires than single-phase
b) It provides more efficient power delivery for large loads
c) It eliminates the need for grounding
d) It converts AC to DC