NEW MEXICO ES-2 CATHODIC & LIGHTNING PROTECTION
SYSTEMS COMPLETE EXAM QUESTIONS AND VERIFIED
ANSWERS | 2026–2027 LATEST UPDATE | GUARANTEED
PASS | DETAILED RATIONALES | FULL STUDY GUIDE | EXAM
PREP | PRACTICE TEST | CERTIFICATION PREPARATION
SECTION ONE: QUESTIONS 1–100
1) What is the minimum negative structure-to-soil potential required to indicate adequate cathodic
protection for a buried steel pipeline per NACE/AMPP standards?
A) –0.70 V versus Cu/CuSO₄
B) –0.85 V versus Cu/CuSO₄
C) –1.00 V versus Cu/CuSO₄
D) –1.20 V versus Cu/CuSO₄
Correct Answer: B) –0.85 V versus Cu/CuSO₄
Rationale: The widely accepted NACE/AMPP criterion for cathodic protection of steel is a structure-to-
soil potential of –0.85 V or more negative relative to a copper/copper-sulfate reference electrode.
This potential ensures that the steel is polarized to a level where corrosion is thermodynamically
unfavorable. Options A, C, and D represent incorrect potential values for this standard criterion.
2) Which component converts alternating current (AC) to direct current (DC) in an impressed
current cathodic protection (ICCP) rectifier?
A) Transformer
B) Inverter
C) Diode bridge
D) Inductor
Correct Answer: C) Diode bridge
Rationale: A diode bridge rectifier converts AC to DC by allowing current flow in only one direction.
Transformers step voltage up or down, inverters convert DC to AC, and inductors store energy in a
magnetic field. The rectifier's output is the DC power that drives the protective current between the
anodes and the structure.
3) What is the equivalent resistance of two 100 Ω resistors connected in parallel?
A) 200 Ω
B) 100 Ω
C) 50 Ω
D) 25 Ω
,Correct Answer: C) 50 Ω
Rationale: For parallel resistors, the equivalent resistance is calculated using the reciprocal formula:
1/Req = 1/R₁ + 1/R₂. For two 100 Ω resistors in parallel, 1/Req = 1/100 + 1/100 = 2/100, so Req = 50
Ω. This is less than the smallest individual resistance, which is characteristic of parallel circuits. Series
resistances would add directly, but this is not a series configuration.
4) According to the NEC, what is the minimum burial depth for a ½-inch EMT conduit used for
underground feeder circuits in non-corrosive soil?
A) 6 inches
B) 12 inches
C) 18 inches
D) 24 inches
Correct Answer: B) 12 inches
Rationale: NEC Section 300.5 requires a minimum cover depth of 12 inches for EMT conduit in non-
corrosive soil when used for underground feeder circuits. This depth provides adequate protection
against physical damage while allowing for proper installation. Options A, C, and D represent
incorrect depths for this specific application, though deeper burial may be required in other
conditions.
5) What is the primary purpose of equipotential bonding in a lightning protection system?
A) To reduce the overall resistance of the grounding system
B) To prevent dangerous voltage differences between metallic objects during a strike
C) To increase the height of air terminals
D) To provide a backup power source during outages
Correct Answer: B) To prevent dangerous voltage differences between metallic objects during a
strike
Rationale: Equipotential bonding connects metallic objects to equalize their electrical potentials,
preventing side-flashing and arcing during a lightning strike. This protects people and equipment
from dangerous voltage differences. Resistance reduction is achieved through grounding electrodes,
not bonding, and air terminals capture the strike rather than benefiting from bonding.
6) Which reference electrode is most widely used for field monitoring of cathodic protection
systems?
A) Silver/silver chloride
B) Copper/copper-sulfate
C) Zinc/zinc sulfate
D) Mercury/mercuric sulfate
Correct Answer: B) Copper/copper-sulfate
Rationale: The copper/copper-sulfate (Cu/CuSO₄) reference electrode is the industry standard for
cathodic protection potential measurements due to its stability, reliability, and ease of use in field
conditions. Silver/silver chloride is used in marine environments, while zinc and mercury electrodes
,are less common for CP field work. The Cu/CuSO₄ electrode provides a consistent reference potential
for structure-to-soil measurements.
7) A cathodic protection rectifier delivers 5 A of current at 24 V DC. How much power is consumed
by the rectifier?
A) 120 W
B) 4.8 W
C) 24 W
D) 5 W
Correct Answer: A) 120 W
Rationale: Electrical power is calculated using the formula P = V × I, where V is voltage and I is
current. With 24 V and 5 A, P = 24 × 5 = 120 W. The other options represent incorrect mathematical
computations: 4.8 W would be 24/5, 24 W ignores current, and 5 W ignores voltage. This power
calculation is fundamental for CP system design and energy consumption estimation.
8) What does Article 250 of the National Electrical Code specifically address?
A) General requirements for electrical installations
B) Grounding and bonding
C) Wiring methods and materials
D) Communications circuits
Correct Answer: B) Grounding and bonding
Rationale: NEC Article 250 provides comprehensive requirements for grounding and bonding of
electrical systems, including service grounding, equipment grounding, and bonding of metallic
systems. Article 110 covers general requirements, Article 300 covers wiring methods, and Article 800
covers communications circuits. Article 250 is essential for CP and lightning protection installations.
9) In a lightning protection system, what is the recommended maximum spacing between air
terminals on a sloped roof per NFPA 780?
A) 10 feet
B) 15 feet
C) 20 feet
D) 25 feet
Correct Answer: C) 20 feet
Rationale: NFPA 780 specifies a maximum spacing of 20 feet between air terminals on sloped roofs to
ensure adequate coverage and interception of lightning strikes. This spacing helps maintain
protection within the rolling sphere requirements. Options A and B are too restrictive, while option D
exceeds the maximum allowed spacing. Proper terminal placement is critical for system effectiveness.
10) What is an "instant-off" potential measurement in cathodic protection testing?
A) A reading taken 30 minutes after the rectifier is turned off
, B) A reading taken immediately after the rectifier is switched off
C) A reading taken while the rectifier is operating at full load
D) A reading taken using a low-impedance voltmeter after a 2-second pause
Correct Answer: B) A reading taken immediately after the rectifier is switched off
Rationale: An instant-off measurement captures the true structure potential immediately after
rectifier interruption, before IR drop (voltage drop from current flow through soil) dissipates. This
reading more accurately reflects the polarization potential. Waiting 30 minutes would allow
depolarization, and readings taken during operation include IR drop error. Low-impedance meters
may introduce measurement errors.
11) What backfill material is recommended when installing a packaged sacrificial anode to ensure
optimal performance?
A) Dry sand
B) Bentonite slurry
C) Gravel only
D) Concrete
Correct Answer: B) Bentonite slurry
Rationale: Bentonite slurry is the recommended backfill material for packaged sacrificial anodes
because it retains moisture and provides a low-resistivity environment around the anode, enhancing
current distribution and anode performance. Dry sand and gravel have high resistivity, while concrete
would create an alkaline environment that may interfere with anode function. Proper backfill is
essential for effective anode operation.
12) Which material is commonly used for high-current ICCP anodes due to its durability and high
silicon content?
A) Pure titanium
B) High silicon cast iron (HSCI)
C) Zinc alloy
D) Magnesium
Correct Answer: B) High silicon cast iron (HSCI)
Rationale: High silicon cast iron anodes are favored for impressed current cathodic protection
because they offer long service life, high corrosion resistance, and ability to operate at high current
densities in aggressive environments. Pure titanium requires precious metal coatings, and
zinc/magnesium are sacrificial anode materials. HSCI provides a cost-effective, durable solution for
many CP applications.
13) The NEC requires that bonding jumpers for metallic water piping be installed within what
distance of the service disconnect?
A) 12 inches
B) 18 inches
SYSTEMS COMPLETE EXAM QUESTIONS AND VERIFIED
ANSWERS | 2026–2027 LATEST UPDATE | GUARANTEED
PASS | DETAILED RATIONALES | FULL STUDY GUIDE | EXAM
PREP | PRACTICE TEST | CERTIFICATION PREPARATION
SECTION ONE: QUESTIONS 1–100
1) What is the minimum negative structure-to-soil potential required to indicate adequate cathodic
protection for a buried steel pipeline per NACE/AMPP standards?
A) –0.70 V versus Cu/CuSO₄
B) –0.85 V versus Cu/CuSO₄
C) –1.00 V versus Cu/CuSO₄
D) –1.20 V versus Cu/CuSO₄
Correct Answer: B) –0.85 V versus Cu/CuSO₄
Rationale: The widely accepted NACE/AMPP criterion for cathodic protection of steel is a structure-to-
soil potential of –0.85 V or more negative relative to a copper/copper-sulfate reference electrode.
This potential ensures that the steel is polarized to a level where corrosion is thermodynamically
unfavorable. Options A, C, and D represent incorrect potential values for this standard criterion.
2) Which component converts alternating current (AC) to direct current (DC) in an impressed
current cathodic protection (ICCP) rectifier?
A) Transformer
B) Inverter
C) Diode bridge
D) Inductor
Correct Answer: C) Diode bridge
Rationale: A diode bridge rectifier converts AC to DC by allowing current flow in only one direction.
Transformers step voltage up or down, inverters convert DC to AC, and inductors store energy in a
magnetic field. The rectifier's output is the DC power that drives the protective current between the
anodes and the structure.
3) What is the equivalent resistance of two 100 Ω resistors connected in parallel?
A) 200 Ω
B) 100 Ω
C) 50 Ω
D) 25 Ω
,Correct Answer: C) 50 Ω
Rationale: For parallel resistors, the equivalent resistance is calculated using the reciprocal formula:
1/Req = 1/R₁ + 1/R₂. For two 100 Ω resistors in parallel, 1/Req = 1/100 + 1/100 = 2/100, so Req = 50
Ω. This is less than the smallest individual resistance, which is characteristic of parallel circuits. Series
resistances would add directly, but this is not a series configuration.
4) According to the NEC, what is the minimum burial depth for a ½-inch EMT conduit used for
underground feeder circuits in non-corrosive soil?
A) 6 inches
B) 12 inches
C) 18 inches
D) 24 inches
Correct Answer: B) 12 inches
Rationale: NEC Section 300.5 requires a minimum cover depth of 12 inches for EMT conduit in non-
corrosive soil when used for underground feeder circuits. This depth provides adequate protection
against physical damage while allowing for proper installation. Options A, C, and D represent
incorrect depths for this specific application, though deeper burial may be required in other
conditions.
5) What is the primary purpose of equipotential bonding in a lightning protection system?
A) To reduce the overall resistance of the grounding system
B) To prevent dangerous voltage differences between metallic objects during a strike
C) To increase the height of air terminals
D) To provide a backup power source during outages
Correct Answer: B) To prevent dangerous voltage differences between metallic objects during a
strike
Rationale: Equipotential bonding connects metallic objects to equalize their electrical potentials,
preventing side-flashing and arcing during a lightning strike. This protects people and equipment
from dangerous voltage differences. Resistance reduction is achieved through grounding electrodes,
not bonding, and air terminals capture the strike rather than benefiting from bonding.
6) Which reference electrode is most widely used for field monitoring of cathodic protection
systems?
A) Silver/silver chloride
B) Copper/copper-sulfate
C) Zinc/zinc sulfate
D) Mercury/mercuric sulfate
Correct Answer: B) Copper/copper-sulfate
Rationale: The copper/copper-sulfate (Cu/CuSO₄) reference electrode is the industry standard for
cathodic protection potential measurements due to its stability, reliability, and ease of use in field
conditions. Silver/silver chloride is used in marine environments, while zinc and mercury electrodes
,are less common for CP field work. The Cu/CuSO₄ electrode provides a consistent reference potential
for structure-to-soil measurements.
7) A cathodic protection rectifier delivers 5 A of current at 24 V DC. How much power is consumed
by the rectifier?
A) 120 W
B) 4.8 W
C) 24 W
D) 5 W
Correct Answer: A) 120 W
Rationale: Electrical power is calculated using the formula P = V × I, where V is voltage and I is
current. With 24 V and 5 A, P = 24 × 5 = 120 W. The other options represent incorrect mathematical
computations: 4.8 W would be 24/5, 24 W ignores current, and 5 W ignores voltage. This power
calculation is fundamental for CP system design and energy consumption estimation.
8) What does Article 250 of the National Electrical Code specifically address?
A) General requirements for electrical installations
B) Grounding and bonding
C) Wiring methods and materials
D) Communications circuits
Correct Answer: B) Grounding and bonding
Rationale: NEC Article 250 provides comprehensive requirements for grounding and bonding of
electrical systems, including service grounding, equipment grounding, and bonding of metallic
systems. Article 110 covers general requirements, Article 300 covers wiring methods, and Article 800
covers communications circuits. Article 250 is essential for CP and lightning protection installations.
9) In a lightning protection system, what is the recommended maximum spacing between air
terminals on a sloped roof per NFPA 780?
A) 10 feet
B) 15 feet
C) 20 feet
D) 25 feet
Correct Answer: C) 20 feet
Rationale: NFPA 780 specifies a maximum spacing of 20 feet between air terminals on sloped roofs to
ensure adequate coverage and interception of lightning strikes. This spacing helps maintain
protection within the rolling sphere requirements. Options A and B are too restrictive, while option D
exceeds the maximum allowed spacing. Proper terminal placement is critical for system effectiveness.
10) What is an "instant-off" potential measurement in cathodic protection testing?
A) A reading taken 30 minutes after the rectifier is turned off
, B) A reading taken immediately after the rectifier is switched off
C) A reading taken while the rectifier is operating at full load
D) A reading taken using a low-impedance voltmeter after a 2-second pause
Correct Answer: B) A reading taken immediately after the rectifier is switched off
Rationale: An instant-off measurement captures the true structure potential immediately after
rectifier interruption, before IR drop (voltage drop from current flow through soil) dissipates. This
reading more accurately reflects the polarization potential. Waiting 30 minutes would allow
depolarization, and readings taken during operation include IR drop error. Low-impedance meters
may introduce measurement errors.
11) What backfill material is recommended when installing a packaged sacrificial anode to ensure
optimal performance?
A) Dry sand
B) Bentonite slurry
C) Gravel only
D) Concrete
Correct Answer: B) Bentonite slurry
Rationale: Bentonite slurry is the recommended backfill material for packaged sacrificial anodes
because it retains moisture and provides a low-resistivity environment around the anode, enhancing
current distribution and anode performance. Dry sand and gravel have high resistivity, while concrete
would create an alkaline environment that may interfere with anode function. Proper backfill is
essential for effective anode operation.
12) Which material is commonly used for high-current ICCP anodes due to its durability and high
silicon content?
A) Pure titanium
B) High silicon cast iron (HSCI)
C) Zinc alloy
D) Magnesium
Correct Answer: B) High silicon cast iron (HSCI)
Rationale: High silicon cast iron anodes are favored for impressed current cathodic protection
because they offer long service life, high corrosion resistance, and ability to operate at high current
densities in aggressive environments. Pure titanium requires precious metal coatings, and
zinc/magnesium are sacrificial anode materials. HSCI provides a cost-effective, durable solution for
many CP applications.
13) The NEC requires that bonding jumpers for metallic water piping be installed within what
distance of the service disconnect?
A) 12 inches
B) 18 inches
