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Free ETT Practice Questions

10 free, exam-style NETA ETT (ETT) practice questions with answers and explanations. No signup required. Work through them below, then take the full free ETT practice test to study every exam domain.

The ETT exam has 100 questions and runs 2 hours.

These 10 free ETT questions are organized by exam domain, so you can see how each part of the NETA ETT blueprint is tested. Reveal the answer and explanation under each question.

Domain 1: Safety 15% of exam

Question 1

A technician reviews an arc-flash label and notes the arc-flash boundary. Which statement correctly describes what that boundary represents?

  1. The closest distance an unqualified person may stand while a qualified person works on energized equipment
  2. The distance within which a second-degree burn could occur because incident energy reaches 1.2 cal/cm²
  3. The point beyond which no arc-rated PPE is required because the area is considered safe
  4. A fixed distance of 1.0 m for any equipment rated 600 V or less, set by the limited approach table
Show answer & explanation

Correct answer: B - The distance within which a second-degree burn could occur because incident energy reaches 1.2 cal/cm²

Question 2

During acceptance testing, a single driven ground rod measures 30 ohms by the fall-of-potential method. According to NEC 250.53(A)(2), the correct conclusion is that the electrode:

  1. Has failed the grounding electrode test and the rod must therefore be rejected, pulled, and replaced at another location
  2. Must be supplemented by one additional electrode, since a single rod need not reach 25 ohms
  3. Is acceptable as installed because 30 ohms is within the allowable tolerance for a commercial service
  4. Requires a supplemental electrode only if the measured resistance later rises above 50 ohms under load
Show answer & explanation

Correct answer: B - Must be supplemented by one additional electrode, since a single rod need not reach 25 ohms

Domain 2: Electrical Testing Fundamentals and Theory 25% of exam

Question 3

An insulation resistance test on a motor winding reads 900 MΩ at 1 minute and 2,700 MΩ at 10 minutes (corrected to 40°C). What is the polarization index, and how should it be interpreted per IEEE 43?

  1. 0.33 - the winding is contaminated and should not be energized
  2. 1.0 - the reading is invalid because the insulation resistance exceeds 5,000 MΩ
  3. 3.0 - acceptable, since a PI of 2.0 or greater indicates good insulation
  4. 3.0 - marginal, because motor windings require a minimum PI of 4.0 to pass
Show answer & explanation

Correct answer: C - 3.0 - acceptable, since a PI of 2.0 or greater indicates good insulation

Question 4

On a one-line diagram, a relay is labeled with ANSI/IEEE device function number 87. This device provides:

  1. Differential protection, comparing current entering and leaving the protected zone
  2. Instantaneous overcurrent protection that operates with no intentional time delay
  3. Undervoltage protection that trips when the monitored voltage falls below a preset threshold for a set time
  4. Lockout function, requiring manual reset before the equipment can be re-energized
Show answer & explanation

Correct answer: A - Differential protection, comparing current entering and leaving the protected zone

Domain 3: Component Testing 55% of exam

Question 5

A transformer turns-ratio (TTR) test is performed at every tap. On one tap the measured ratio deviates 0.9% from the nameplate ratio. Per IEEE C57.12.90 and ANSI/NETA acceptance criteria, the technician should:

  1. Accept the result, because deviations up to 2% are normal for field measurements
  2. Investigate the result, since the measured ratio should be within 0.5% of nameplate
  3. Record the value and move on; only the rated (nominal) tap is required to meet tolerance
  4. Immediately condemn the transformer, because any measurable deviation indicates a shorted turn that cannot be tested further
Show answer & explanation

Correct answer: B - Investigate the result, since the measured ratio should be within 0.5% of nameplate

Question 6

A maintenance plan calls for testing a 15-year-old extruded XLPE medium-voltage cable. Why is a DC high-potential (hipot) test generally NOT recommended for this cable?

  1. DC voltage cannot be generated at a high enough level to stress medium-voltage insulation
  2. DC testing is only valid on paper-insulated lead-covered (PILC) cable and produces no usable reading whatsoever on solid extruded XLPE
  3. DC hipot requires de-energizing adjacent circuits, which is impractical during maintenance
  4. DC voltage traps space charge in aged extruded insulation, which can cause failure once the cable returns to AC service
Show answer & explanation

Correct answer: D - DC voltage traps space charge in aged extruded insulation, which can cause failure once the cable returns to AC service

Question 7

A dissolved gas analysis (DGA) of transformer oil returns an elevated level of acetylene (C₂H₂). This most strongly indicates:

  1. Normal aging of the cellulose paper insulation
  2. Air ingress through a leaking gasket on the conservator
  3. High-energy arcing inside the transformer
  4. Low-temperature overheating of the oil below 200°C
Show answer & explanation

Correct answer: C - High-energy arcing inside the transformer

Question 8

A station battery undergoes a performance (capacity) test. The battery delivers 78% of its rated capacity. According to IEEE 450, the correct action is to:

  1. Replace the battery, because capacity has dropped below 80% of rated
  2. Return the battery to service; it remains acceptable until capacity falls below 50%
  3. Equalize-charge the battery, which will restore the lost capacity to above 80%
  4. Take no action other than recording the value as the new baseline for future tests
Show answer & explanation

Correct answer: A - Replace the battery, because capacity has dropped below 80% of rated

Question 9

When testing an overcurrent protection scheme, a technician injects current into the primary of the in-service current transformer rather than into the relay test terminals. The PRIMARY advantage of this primary-injection approach is that it:

  1. Is faster and requires lower-capacity test equipment than secondary injection
  2. Verifies the entire circuit - CT, wiring, and relay - as a complete system
  3. Checks the relay logic alone, separate from the CT and the field wiring
  4. Allows the relay to be tested without removing the equipment from service
Show answer & explanation

Correct answer: B - Verifies the entire circuit - CT, wiring, and relay - as a complete system

Domain 4: Systems and Commissioning 5% of exam

Question 10

On a commissioning project, every protective relay, breaker, and CT has passed its individual component test. A complete system functional test is then performed. What is the PRIMARY purpose of this functional test?

  1. To repeat the component tests a second time to confirm the original readings
  2. To satisfy the equipment manufacturer's warranty, which requires a complete duplicate set of component results to be submitted
  3. To confirm that the components operate together correctly as an integrated system, including trip and control logic
  4. To establish the arc-flash incident energy values for the equipment labels
Show answer & explanation

Correct answer: C - To confirm that the components operate together correctly as an integrated system, including trip and control logic

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