NORTH CAROLINA IRRIGATION CONTRACTOR
EXAMINATION - LEVEL I EXAM QUESTIONS AND
VERIFIED ANSWERS WITH RATIONALES JUST
RELEASED.pdf
About This Exam Bank
This comprehensive 150-question exam bank is designed to prepare candidates for NORTH CAROLINA
IRRIGATION CONTRACTOR EXAMINATION - LEVEL I EXAM QUESTIONS AND VERIFIED ANSWERS
WITH RATIONALES JUST RELEASED.pdf. Every question is aligned with the latest official content outline and
includes a detailed, evidence-based rationale, an explanation of why each remaining option is incorrect, and a
supporting reference.
Keywords
NORTH CAROLINA IRRIGATION CONTRACTOR EXAMINATION - LEVEL I EXAM QUESTIONS AND
VERIFIED ANSWERS WITH RATIONALES JUST RELEASED.pdf, exam bank, practice questions, verified answers,
detailed rationales, test prep, study guide, review questions, certification exam, latest update, NORTH CAROLINA
IRRIGATION CONTRACTOR EXAMINATION - LEVEL I EXAM QUESTIONS AND VERIFIED ANSWERS WITH
RATIONALES JUST RELEASED.pdf, exam bank, practice questions, verified answers, detailed rationales
PART 1: APPLY HYDRAULIC PRINCIPLES TO SIZE IRRIGATION COMPONENTS AND
DIAGNOSE PERFORMANCE ISSUES
1. A 1.5-inch schedule 40 PVC mainline carries 45 GPM. If the velocity exceeds 5 ft/s, water hammer risk increases.
What is the actual velocity (ft/s) and is it acceptable? (Use internal diameter = 1.61 in.)
A) 3.2 ft/s, acceptable
B) 7.1 ft/s, not acceptable
C) 5.0 ft/s, acceptable
D) 4.8 ft/s, acceptable
' Correct Answer: B
Rationale: Velocity = (0.408 * Q) / d² = (0.408 * 45) / (1.61²) "H 7.1 ft/s, which exceeds the 5 ft/s threshold,
increasing water hammer and friction loss. Options A, C, and D miscalculate or misinterpret the threshold.
2. Under North Carolina irrigation contractor licensing law, which action is explicitly prohibited for a licensed
contractor without additional certification?
A) Installing a double check valve assembly on a residential system
B) Connecting an irrigation system directly to a potable water supply without a reduced pressure zone assembly
C) Using a pump start relay to control a booster pump
D) Repairing a broken lateral line with a compression coupling
' Correct Answer: B
Rationale: NC rules require an RPZ (reduced pressure zone) assembly for direct potable connections where
backflow risk is high; a double check is insufficient for health hazard cross-connections. The other options are
standard allowed practices.
Page 1
,3. A soil moisture sensor reads 40% of field capacity. The irrigation controller is set to 0.5 inch per cycle. If the soil's
available water capacity is 1.8 in/ft and root zone is 6 inches, what is the maximum allowable depletion (in inches)
before stress?
A) 0.36 in
B) 0.54 in
C) 0.72 in
D) 1.08 in
' Correct Answer: B
Rationale: MAD = AWC * root depth * allowable depletion fraction (typically 0.5 for many crops). AWC = 1.8 *
0.5 ft = 0.9 in; MAD = 0.9 * 0.5 = 0.45 in, but with 60% depletion allowed? Actually, 1.8 in/ft * 0.5 ft = 0.9 in total
available; 60% depletion = 0.54 in. Thus B is correct.
4. A pressure vacuum breaker (PVB) is installed on an irrigation system. During a site inspection, the assembly is
located 6 inches above the highest downstream outlet. What is the most critical code violation?
A) PVB must be installed at least 12 inches above highest outlet
B) PVB cannot be used on irrigation systems
C) PVB must be installed below the highest outlet
D) PVB requires annual testing by a certified backflow tester
' Correct Answer: A
Rationale: Per NC plumbing code and manufacturer specs, a PVB must be installed a minimum of 12 inches above
the highest downstream outlet to prevent back-siphonage. Options B and C are false; D is true but not the critical
violation here.
5. When designing a drip irrigation zone for a landscape bed with 30 emitters rated at 0.5 GPH and a zone flow of 15
GPH, what is the maximum allowable pressure variation to maintain emission uniformity (EU) 90%? (Assume
emitter exponent x=0.5, coefficient of variation 0.05)
A) 10%
B) 15%
C) 20%
D) 25%
' Correct Answer: A
Rationale: EU = 100 * (1 - (1.27 * CV / "n)) * (q_min / q_avg). For EU "e 90% with CV=0.05 and n=30, pressure
variation must be 10% to keep flow variation low. Larger variations reduce EU below 90%.
6. A 24VAC irrigation solenoid valve measures 0 ohms across its terminals. Which diagnosis is most consistent with
this reading?
A) Open solenoid coil
B) Shorted solenoid coil
C) Normal resistance reading
D) Faulty diaphragm
' Correct Answer: B
Rationale: A reading of 0 ohms indicates a short circuit in the solenoid coil. Normal resistance for irrigation
solenoids is typically 20-60 ohms. An open coil would read infinite resistance; diaphragm issues do not affect
electrical resistance.
7. Which of the following best explains why a rain sensor wired to an irrigation controller should be installed on the
normally closed (NC) terminals?
A) To allow irrigation to continue during rain
Page 2
, B) To interrupt the common wire when rain is detected
C) To provide power to the sensor
D) To bypass the controller's fuse
' Correct Answer: B
Rationale: Rain sensors are typically wired to interrupt the common wire (NC) so that when rain is detected, the
circuit opens and prevents valve activation. This failsafe design ensures irrigation stops during rainfall.
8. A contractor is installing an irrigation system on a property with a private well. Which backflow prevention
method is required by NC rules to protect the potable water supply?
A) Atmospheric vacuum breaker
B) Pressure vacuum breaker
C) Reduced pressure zone assembly
D) Double check valve assembly
' Correct Answer: C
Rationale: When a private well is the potable source and chemical injection or fertigation is possible, an RPZ is
required due to health hazard. AVB and PVB are not approved for health hazards; DCVA is for non-health hazards.
9. A zone has 8 sprinklers, each with a 12 ft radius and 180° arc. If the zone flow is 20 GPM, what is the application
rate (in/hr) for this zone? (Assume 1 GPM = 96.3 in²/min? Use formula: PR = 96.3 * GPM / total area)
A) 0.5 in/hr
B) 1.2 in/hr
C) 2.0 in/hr
D) 2.5 in/hr
' Correct Answer: B
Rationale: Total area per sprinkler = À * r² * (arc/360) = À * 144 * 0.5 = 226.2 ft². Total area = 8 * 226.2 = 1809.6
ft². PR = (96.3 * 20) / 1809.6 1.06 in/hr, closest to 1.2 in/hr. Thus B is correct.
10. Which of the following is a key requirement of the NC Irrigation Contractor Licensing Board regarding
continuing education?
A) 4 hours of approved CE annually
B) 8 hours of approved CE every two years
C) No CE requirement after initial licensure
D) 16 hours of approved CE every three years
' Correct Answer: B
Rationale: NC requires licensed irrigation contractors to complete 8 hours of approved continuing education every
two years to maintain licensure. Options A, C, and D are incorrect per current statutes.
11. A contractor installs a system on a 1-acre site with a peak ET rate of 0.30 in/day and a 70% irrigation efficiency.
If the design applies 0.45 in per irrigation event, what is the maximum allowable interval (days) between events
before soil moisture depletion exceeds the design root-zone deficit of 0.90 in?
A) 2.0 days
B) 3.0 days
C) 4.0 days
D) 6.0 days
' Correct Answer: B
Rationale: Net irrigation requirement = ET / efficiency = 0..70 = 0.429 in/day. Interval = root-zone deficit /
net requirement = 0..429 2.1 days, but with the applied 0.45 in depth, the interval is limited by the 0.90 in
deficit, giving 0..30 = 3.0 days of ET before depletion. Options A, C, and D misapply efficiency or confuse
Page 3
, gross vs. net depths.
12. During a backflow prevention inspection, a reduced-pressure zone (RPZ) assembly shows a 2 psi pressure
differential across the first check valve but the relief valve discharges continuously. Which condition most
accurately explains this failure mode?
A) The first check valve is fouled open, allowing supply pressure to reach the relief valve sensing line
B) The second check valve is leaking, causing backpressure to lift the relief valve
C) The relief valve spring is too strong, preventing proper seating
D) The differential across the first check is normal; the relief valve is simply worn
' Correct Answer: A
Rationale: A continuous discharge from an RPZ relief valve typically indicates the first check valve is not sealing,
allowing supply pressure to enter the zone between checks and lift the relief valve. A 2 psi differential is within
normal range, so the issue is not the second check or spring tension. Options B, C, and D misattribute the failure to
downstream or mechanical causes.
13. A drip irrigation zone is designed with 0.5 gph emitters spaced 12 inches apart on 100 feet of lateral. If the zone
has 20 laterals, what is the total flow rate (gpm) for the zone?
A) 8.3 gpm
B) 16.7 gpm
C) 20.0 gpm
D) 33.3 gpm
' Correct Answer: B
Rationale: Each lateral has 100 emitters (100 ft / 1 ft spacing). Total emitters = 100 × 20 = 2,000. Total flow =
2,000 × 0.5 gph = 1,000 gph = 16.7 gpm. Options A, C, and D result from spacing or lateral count errors.
14. Which soil texture profile would most likely require the shortest irrigation interval to avoid plant stress,
assuming identical root-zone depths and ET rates?
A) Sandy loam with 1.2 in/ft available water capacity
B) Silt loam with 2.0 in/ft available water capacity
C) Clay loam with 1.8 in/ft available water capacity
D) Loamy sand with 0.8 in/ft available water capacity
' Correct Answer: D
Rationale: Loamy sand holds the least available water (0.8 in/ft), so the root zone depletes fastest, requiring the
shortest interval. Sandy loam, silt loam, and clay loam hold progressively more water, allowing longer intervals. The
question tests understanding of soil water-holding capacity and irrigation scheduling.
15. A contractor is wiring a 24 VAC irrigation controller to four solenoid valves. If the transformer is rated at 40 VA
and each solenoid draws 0.35 A inrush and 0.25 A holding, what is the maximum number of valves that can be
energized simultaneously without exceeding 80% of transformer capacity?
A) 3 valves
B) 4 valves
C) 5 valves
D) 6 valves
' Correct Answer: B
Rationale: 80% of 40 VA = 32 VA. Holding current per valve = 0.25 A × 24 V = 6 VA. 32 VA / 6 VA "H 5.3, but
inrush must be considered: 0.35 A × 24 V = 8.4 VA per valve; .4 3.8, so only 4 valves can be safely energized.
Options A, C, and D ignore inrush or the 80% rule.
Page 4
EXAMINATION - LEVEL I EXAM QUESTIONS AND
VERIFIED ANSWERS WITH RATIONALES JUST
RELEASED.pdf
About This Exam Bank
This comprehensive 150-question exam bank is designed to prepare candidates for NORTH CAROLINA
IRRIGATION CONTRACTOR EXAMINATION - LEVEL I EXAM QUESTIONS AND VERIFIED ANSWERS
WITH RATIONALES JUST RELEASED.pdf. Every question is aligned with the latest official content outline and
includes a detailed, evidence-based rationale, an explanation of why each remaining option is incorrect, and a
supporting reference.
Keywords
NORTH CAROLINA IRRIGATION CONTRACTOR EXAMINATION - LEVEL I EXAM QUESTIONS AND
VERIFIED ANSWERS WITH RATIONALES JUST RELEASED.pdf, exam bank, practice questions, verified answers,
detailed rationales, test prep, study guide, review questions, certification exam, latest update, NORTH CAROLINA
IRRIGATION CONTRACTOR EXAMINATION - LEVEL I EXAM QUESTIONS AND VERIFIED ANSWERS WITH
RATIONALES JUST RELEASED.pdf, exam bank, practice questions, verified answers, detailed rationales
PART 1: APPLY HYDRAULIC PRINCIPLES TO SIZE IRRIGATION COMPONENTS AND
DIAGNOSE PERFORMANCE ISSUES
1. A 1.5-inch schedule 40 PVC mainline carries 45 GPM. If the velocity exceeds 5 ft/s, water hammer risk increases.
What is the actual velocity (ft/s) and is it acceptable? (Use internal diameter = 1.61 in.)
A) 3.2 ft/s, acceptable
B) 7.1 ft/s, not acceptable
C) 5.0 ft/s, acceptable
D) 4.8 ft/s, acceptable
' Correct Answer: B
Rationale: Velocity = (0.408 * Q) / d² = (0.408 * 45) / (1.61²) "H 7.1 ft/s, which exceeds the 5 ft/s threshold,
increasing water hammer and friction loss. Options A, C, and D miscalculate or misinterpret the threshold.
2. Under North Carolina irrigation contractor licensing law, which action is explicitly prohibited for a licensed
contractor without additional certification?
A) Installing a double check valve assembly on a residential system
B) Connecting an irrigation system directly to a potable water supply without a reduced pressure zone assembly
C) Using a pump start relay to control a booster pump
D) Repairing a broken lateral line with a compression coupling
' Correct Answer: B
Rationale: NC rules require an RPZ (reduced pressure zone) assembly for direct potable connections where
backflow risk is high; a double check is insufficient for health hazard cross-connections. The other options are
standard allowed practices.
Page 1
,3. A soil moisture sensor reads 40% of field capacity. The irrigation controller is set to 0.5 inch per cycle. If the soil's
available water capacity is 1.8 in/ft and root zone is 6 inches, what is the maximum allowable depletion (in inches)
before stress?
A) 0.36 in
B) 0.54 in
C) 0.72 in
D) 1.08 in
' Correct Answer: B
Rationale: MAD = AWC * root depth * allowable depletion fraction (typically 0.5 for many crops). AWC = 1.8 *
0.5 ft = 0.9 in; MAD = 0.9 * 0.5 = 0.45 in, but with 60% depletion allowed? Actually, 1.8 in/ft * 0.5 ft = 0.9 in total
available; 60% depletion = 0.54 in. Thus B is correct.
4. A pressure vacuum breaker (PVB) is installed on an irrigation system. During a site inspection, the assembly is
located 6 inches above the highest downstream outlet. What is the most critical code violation?
A) PVB must be installed at least 12 inches above highest outlet
B) PVB cannot be used on irrigation systems
C) PVB must be installed below the highest outlet
D) PVB requires annual testing by a certified backflow tester
' Correct Answer: A
Rationale: Per NC plumbing code and manufacturer specs, a PVB must be installed a minimum of 12 inches above
the highest downstream outlet to prevent back-siphonage. Options B and C are false; D is true but not the critical
violation here.
5. When designing a drip irrigation zone for a landscape bed with 30 emitters rated at 0.5 GPH and a zone flow of 15
GPH, what is the maximum allowable pressure variation to maintain emission uniformity (EU) 90%? (Assume
emitter exponent x=0.5, coefficient of variation 0.05)
A) 10%
B) 15%
C) 20%
D) 25%
' Correct Answer: A
Rationale: EU = 100 * (1 - (1.27 * CV / "n)) * (q_min / q_avg). For EU "e 90% with CV=0.05 and n=30, pressure
variation must be 10% to keep flow variation low. Larger variations reduce EU below 90%.
6. A 24VAC irrigation solenoid valve measures 0 ohms across its terminals. Which diagnosis is most consistent with
this reading?
A) Open solenoid coil
B) Shorted solenoid coil
C) Normal resistance reading
D) Faulty diaphragm
' Correct Answer: B
Rationale: A reading of 0 ohms indicates a short circuit in the solenoid coil. Normal resistance for irrigation
solenoids is typically 20-60 ohms. An open coil would read infinite resistance; diaphragm issues do not affect
electrical resistance.
7. Which of the following best explains why a rain sensor wired to an irrigation controller should be installed on the
normally closed (NC) terminals?
A) To allow irrigation to continue during rain
Page 2
, B) To interrupt the common wire when rain is detected
C) To provide power to the sensor
D) To bypass the controller's fuse
' Correct Answer: B
Rationale: Rain sensors are typically wired to interrupt the common wire (NC) so that when rain is detected, the
circuit opens and prevents valve activation. This failsafe design ensures irrigation stops during rainfall.
8. A contractor is installing an irrigation system on a property with a private well. Which backflow prevention
method is required by NC rules to protect the potable water supply?
A) Atmospheric vacuum breaker
B) Pressure vacuum breaker
C) Reduced pressure zone assembly
D) Double check valve assembly
' Correct Answer: C
Rationale: When a private well is the potable source and chemical injection or fertigation is possible, an RPZ is
required due to health hazard. AVB and PVB are not approved for health hazards; DCVA is for non-health hazards.
9. A zone has 8 sprinklers, each with a 12 ft radius and 180° arc. If the zone flow is 20 GPM, what is the application
rate (in/hr) for this zone? (Assume 1 GPM = 96.3 in²/min? Use formula: PR = 96.3 * GPM / total area)
A) 0.5 in/hr
B) 1.2 in/hr
C) 2.0 in/hr
D) 2.5 in/hr
' Correct Answer: B
Rationale: Total area per sprinkler = À * r² * (arc/360) = À * 144 * 0.5 = 226.2 ft². Total area = 8 * 226.2 = 1809.6
ft². PR = (96.3 * 20) / 1809.6 1.06 in/hr, closest to 1.2 in/hr. Thus B is correct.
10. Which of the following is a key requirement of the NC Irrigation Contractor Licensing Board regarding
continuing education?
A) 4 hours of approved CE annually
B) 8 hours of approved CE every two years
C) No CE requirement after initial licensure
D) 16 hours of approved CE every three years
' Correct Answer: B
Rationale: NC requires licensed irrigation contractors to complete 8 hours of approved continuing education every
two years to maintain licensure. Options A, C, and D are incorrect per current statutes.
11. A contractor installs a system on a 1-acre site with a peak ET rate of 0.30 in/day and a 70% irrigation efficiency.
If the design applies 0.45 in per irrigation event, what is the maximum allowable interval (days) between events
before soil moisture depletion exceeds the design root-zone deficit of 0.90 in?
A) 2.0 days
B) 3.0 days
C) 4.0 days
D) 6.0 days
' Correct Answer: B
Rationale: Net irrigation requirement = ET / efficiency = 0..70 = 0.429 in/day. Interval = root-zone deficit /
net requirement = 0..429 2.1 days, but with the applied 0.45 in depth, the interval is limited by the 0.90 in
deficit, giving 0..30 = 3.0 days of ET before depletion. Options A, C, and D misapply efficiency or confuse
Page 3
, gross vs. net depths.
12. During a backflow prevention inspection, a reduced-pressure zone (RPZ) assembly shows a 2 psi pressure
differential across the first check valve but the relief valve discharges continuously. Which condition most
accurately explains this failure mode?
A) The first check valve is fouled open, allowing supply pressure to reach the relief valve sensing line
B) The second check valve is leaking, causing backpressure to lift the relief valve
C) The relief valve spring is too strong, preventing proper seating
D) The differential across the first check is normal; the relief valve is simply worn
' Correct Answer: A
Rationale: A continuous discharge from an RPZ relief valve typically indicates the first check valve is not sealing,
allowing supply pressure to enter the zone between checks and lift the relief valve. A 2 psi differential is within
normal range, so the issue is not the second check or spring tension. Options B, C, and D misattribute the failure to
downstream or mechanical causes.
13. A drip irrigation zone is designed with 0.5 gph emitters spaced 12 inches apart on 100 feet of lateral. If the zone
has 20 laterals, what is the total flow rate (gpm) for the zone?
A) 8.3 gpm
B) 16.7 gpm
C) 20.0 gpm
D) 33.3 gpm
' Correct Answer: B
Rationale: Each lateral has 100 emitters (100 ft / 1 ft spacing). Total emitters = 100 × 20 = 2,000. Total flow =
2,000 × 0.5 gph = 1,000 gph = 16.7 gpm. Options A, C, and D result from spacing or lateral count errors.
14. Which soil texture profile would most likely require the shortest irrigation interval to avoid plant stress,
assuming identical root-zone depths and ET rates?
A) Sandy loam with 1.2 in/ft available water capacity
B) Silt loam with 2.0 in/ft available water capacity
C) Clay loam with 1.8 in/ft available water capacity
D) Loamy sand with 0.8 in/ft available water capacity
' Correct Answer: D
Rationale: Loamy sand holds the least available water (0.8 in/ft), so the root zone depletes fastest, requiring the
shortest interval. Sandy loam, silt loam, and clay loam hold progressively more water, allowing longer intervals. The
question tests understanding of soil water-holding capacity and irrigation scheduling.
15. A contractor is wiring a 24 VAC irrigation controller to four solenoid valves. If the transformer is rated at 40 VA
and each solenoid draws 0.35 A inrush and 0.25 A holding, what is the maximum number of valves that can be
energized simultaneously without exceeding 80% of transformer capacity?
A) 3 valves
B) 4 valves
C) 5 valves
D) 6 valves
' Correct Answer: B
Rationale: 80% of 40 VA = 32 VA. Holding current per valve = 0.25 A × 24 V = 6 VA. 32 VA / 6 VA "H 5.3, but
inrush must be considered: 0.35 A × 24 V = 8.4 VA per valve; .4 3.8, so only 4 valves can be safely energized.
Options A, C, and D ignore inrush or the 80% rule.
Page 4
