CP 2 Practice Questions

These CP 2 practice questions focus on field testing, measurement interpretation, rectifiers, survey methods, criteria, and common troubleshooting.

Study Focus

CP 2-level study should emphasize correct field measurement technique, reference electrode use, rectifier inspection, interruption, test stations, bonds, isolation, and basic criteria interpretation.

Practice Questions

  1. What is an ON potential?

    1. A potential measured before CP is installed
    2. A potential measured while CP current is flowing
    3. A potential measured only after 24 hours of depolarization
    4. A potential measured without a reference electrode

    Answer: B. An ON potential is measured while CP current is flowing.

  2. Why is an instant-off reading used?

    1. To increase coating resistance
    2. To reduce current-flow voltage drop effects in the measurement
    3. To measure AC voltage only
    4. To permanently de-energize the CP system

    Answer: B. Instant-off readings reduce IR drop associated with CP current flow.

  3. Which reference electrode is commonly used for buried steel in soil?

    1. Copper-copper sulfate
    2. Glass pH electrode
    3. Dry graphite rod only
    4. Thermocouple

    Answer: A. Copper-copper sulfate reference electrodes are commonly used for buried steel in soil.

  4. A rectifier shows high voltage and very low current. What is one possible cause?

    1. Low circuit resistance
    2. Open or high-resistance anode circuit
    3. Perfect current distribution
    4. Reference electrode overfill

    Answer: B. High voltage with low current may indicate an open or high-resistance circuit.

  5. Why should multiple rectifiers be synchronized during interruption testing?

    1. To keep all current sources switching together
    2. To increase AC ripple
    3. To stop all corrosion permanently
    4. To make ON readings more positive

    Answer: A. Unsynchronized interruption can leave current-flow effects in the measurement.

  6. What is one risk of a shorted isolation device?

    1. It can connect unintended structures and increase current demand
    2. It removes all electrolyte from the soil
    3. It makes all readings native
    4. It prevents all metallic continuity

    Answer: A. Shorted isolation can connect unintended structures and change CP current distribution.

  7. Why should reference electrode type be recorded?

    1. Because readings depend on the reference scale
    2. Because all electrodes give identical values
    3. Because reference electrodes supply rectifier current
    4. Because electrode type only matters for AC readings

    Answer: A. Potential values are meaningful only when the reference electrode scale is known.

  8. What does a test station provide?

    1. Field access to structure leads, bonds, anodes, or other CP test points
    2. A guaranteed proof of protection
    3. AC power conversion
    4. A coating holiday repair

    Answer: A. Test stations provide access for measurements and checks.

  9. Why can one annual test station reading miss a CP problem?

    1. It may not represent conditions between test stations
    2. It always measures every inch of pipeline
    3. It eliminates the need for surveys
    4. It proves coating condition everywhere

    Answer: A. Localized underprotection can exist between test stations.

  10. What should be checked before concluding that a low potential is a real CP deficiency?

    1. Measurement setup, test lead condition, reference electrode contact, and field conditions
    2. Only the paint color of the test station
    3. The website URL
    4. Nothing; the first reading is always final

    Answer: A. Measurement setup errors must be ruled out before diagnosing the CP system.

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