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CWEA ELECTRICAL/INSTRUMENTATION
TECHNOLOGIST GRADE 3 PRACTICE
EXAM 2026/2027 QUESTIONS WITH
VERIFIED ANSWERS & COMPLETE
RATIONALES
**1. A technician is troubleshooting a 4-20 mA analog control
loop in a wastewater treatment plant that is reading 0 mA while
the process is active. Which of the following is the most likely
initial cause of this reading?**
A. A short circuit across the transmitter output terminals
B. A completely open circuit in the loop wiring or a blown fuse in
the power supply
C. A grounded shield wire causing signal attenuation
D. Excessive loop resistance exceeding the power supply
voltage rating
**Correct answer:** B
**Rationale:** A 0 mA reading on a live 4-20 mA loop indicates
a complete loss of current flow, typically caused by an open
wire, broken connection, or blown fuse. A short circuit or high
resistance usually results in loop power faults rather than a
dead zero.
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**2. Which device reduces high voltages and currents to safe,
measurable values for instruments?**
A. Auto transformer
B. Megohmmeter
C. Instrument transformer
D. Variable transformer
**Correct answer:** C
**Rationale:** Instrument transformers (current transformers
and potential transformers) reduce high voltages and currents
to lower, measurable values, allowing safe measurement and
monitoring by instruments and protective devices.
**3. The NEC identifies environments that contain flammable
vapors and gases as which class of hazardous location?**
A. Class I
B. Class II
C. Class III
D. Class IV
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**Correct answer:** A
**Rationale:** Class I locations contain flammable gases or
vapors; Class II contains combustible dusts; Class III contains
ignitable fibers or flyings.
**4. What is the correct formula for Ohm's Law?**
A. V = I × R
B. I = V × R
C. R = V × I
D. V = I ÷ R
**Correct answer:** A
**Rationale:** Ohm's Law states that Voltage = Current ×
Resistance (V = IR). This fundamental relationship allows
calculation of any one value when the other two are known.
**5. A circuit has a resistance of 20 ohms and a voltage of 120
volts. What is the current?**
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A. 2 amps
B. 4 amps
C. 6 amps
D. 8 amps
**Correct answer:** C
**Rationale:** Using Ohm's Law: I = V ÷ R = 120 ÷ 20 = 6
amps.
**6. If 17.32V are applied across a resistance of 50 ohms, how
much power is expended in the resistor?**
A. 3.0 watts
B. 6.0 watts
C. 12.0 watts
D. 24.0 watts
**Correct answer:** B
**Rationale:** Using the power formula P = V²/R: 17.32²
(299.98) ÷ 50 = 5.99 ≈ 6.0 watts.
CWEA ELECTRICAL/INSTRUMENTATION
TECHNOLOGIST GRADE 3 PRACTICE
EXAM 2026/2027 QUESTIONS WITH
VERIFIED ANSWERS & COMPLETE
RATIONALES
**1. A technician is troubleshooting a 4-20 mA analog control
loop in a wastewater treatment plant that is reading 0 mA while
the process is active. Which of the following is the most likely
initial cause of this reading?**
A. A short circuit across the transmitter output terminals
B. A completely open circuit in the loop wiring or a blown fuse in
the power supply
C. A grounded shield wire causing signal attenuation
D. Excessive loop resistance exceeding the power supply
voltage rating
**Correct answer:** B
**Rationale:** A 0 mA reading on a live 4-20 mA loop indicates
a complete loss of current flow, typically caused by an open
wire, broken connection, or blown fuse. A short circuit or high
resistance usually results in loop power faults rather than a
dead zero.
,2 | Page
**2. Which device reduces high voltages and currents to safe,
measurable values for instruments?**
A. Auto transformer
B. Megohmmeter
C. Instrument transformer
D. Variable transformer
**Correct answer:** C
**Rationale:** Instrument transformers (current transformers
and potential transformers) reduce high voltages and currents
to lower, measurable values, allowing safe measurement and
monitoring by instruments and protective devices.
**3. The NEC identifies environments that contain flammable
vapors and gases as which class of hazardous location?**
A. Class I
B. Class II
C. Class III
D. Class IV
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**Correct answer:** A
**Rationale:** Class I locations contain flammable gases or
vapors; Class II contains combustible dusts; Class III contains
ignitable fibers or flyings.
**4. What is the correct formula for Ohm's Law?**
A. V = I × R
B. I = V × R
C. R = V × I
D. V = I ÷ R
**Correct answer:** A
**Rationale:** Ohm's Law states that Voltage = Current ×
Resistance (V = IR). This fundamental relationship allows
calculation of any one value when the other two are known.
**5. A circuit has a resistance of 20 ohms and a voltage of 120
volts. What is the current?**
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A. 2 amps
B. 4 amps
C. 6 amps
D. 8 amps
**Correct answer:** C
**Rationale:** Using Ohm's Law: I = V ÷ R = 120 ÷ 20 = 6
amps.
**6. If 17.32V are applied across a resistance of 50 ohms, how
much power is expended in the resistor?**
A. 3.0 watts
B. 6.0 watts
C. 12.0 watts
D. 24.0 watts
**Correct answer:** B
**Rationale:** Using the power formula P = V²/R: 17.32²
(299.98) ÷ 50 = 5.99 ≈ 6.0 watts.
