100+ Free NGWA CPI Practice Questions

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When calculating Total Dynamic Head (TDH) for a submersible pump installation, which components must be summed?

Static water level, friction losses in drop pipe, and pressure at discharge point

Pump depth, pipe diameter, and motor horsepower

Well casing diameter, screen length, and pump setting depth

Discharge pressure only, since friction losses are negligible for residential wells

to track

2026 Statistics

Key Facts: NGWA CPI Exam

70%

Passing Score

NGWA

Questions Per Exam

NGWA

$75

Exam Fee Per Exam

NGWA

2 exams

Required for CPI

NGWA

24 months

Experience Required

NGWA

7 CEPs

Annual Renewal Requirement

NGWA

The NGWA Certified Pump Installer (CPI) is the only national voluntary certification for groundwater pump installation professionals, administered by the National Ground Water Association. Two exams are required: the water systems general exam plus Exam K (systems under 100 gpm) or Exam L (100 gpm or more), each 50 questions with a 70% passing score and 1-hour time limit. Exams cost $75 each and are delivered through PSI Services at 400+ locations nationwide. Eligibility requires age 20+, 24 months of full-time pump installation experience, and two professional references.

Sample NGWA CPI Practice Questions

Try these sample questions to test your NGWA CPI exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1When calculating Total Dynamic Head (TDH) for a submersible pump installation, which components must be summed?

A.Static water level, friction losses in drop pipe, and pressure at discharge point

B.Pump depth, pipe diameter, and motor horsepower

C.Well casing diameter, screen length, and pump setting depth

D.Discharge pressure only, since friction losses are negligible for residential wells

Explanation: TDH equals the sum of static water level (or drawdown level during pumping), friction losses in the drop pipe and fittings, and the pressure head required at the discharge point (e.g., pressure tank cut-in pressure converted to feet). All three components must be accurately calculated to properly size the pump.

2A residential well pump delivers water 200 ft vertically and requires 50 psi at the pressure tank (approximately 115 ft of head). Friction losses in the drop pipe total 18 ft. What is the approximate TDH?

A.333 ft

B.268 ft

C.200 ft

D.365 ft

Explanation: TDH = static lift (200 ft) + friction losses (18 ft) + discharge pressure head (115 ft) = 333 ft. Converting psi to feet of head uses the factor 2.31 ft per psi (50 psi × 2.31 = 115.5 ft ≈ 115 ft).

3On a pump performance curve, the Best Efficiency Point (BEP) is the operating point at which the pump:

A.Delivers the highest hydraulic efficiency for that impeller

B.Produces the maximum possible flow rate

C.Generates the highest shut-off head

D.Consumes the least electrical current regardless of flow

Explanation: The BEP is the flow-head combination where the pump converts the most input power to useful hydraulic energy, resulting in the highest efficiency. Operating near BEP extends impeller and bearing life and reduces energy costs.

4Net Positive Suction Head Available (NPSHA) for a jet pump installation must be greater than NPSHR to prevent:

A.Cavitation inside the pump

B.Water hammer in the discharge pipe

C.Short cycling of the pressure switch

D.Overloading the motor windings

Explanation: Cavitation occurs when suction pressure drops below the vapor pressure of water, forming vapor bubbles that collapse violently inside the impeller. Ensuring NPSHA exceeds NPSHR by an adequate margin prevents cavitation, which causes noise, vibration, and rapid impeller damage.

5Friction loss in a drop pipe increases as which of the following changes occur?

A.Flow rate increases and pipe diameter decreases

B.Flow rate decreases and pipe diameter increases

C.Static water level rises and pipe length shortens

D.Motor speed decreases and impeller diameter grows

Explanation: Friction loss is directly related to flow velocity in the pipe. Higher flow rate increases velocity, and smaller pipe diameter also increases velocity for the same flow, both of which dramatically increase friction head loss (which varies with the square of velocity).

6A submersible pump motor for a 240-volt, single-phase system uses two hot conductors and one equipment-grounding conductor. What colors are typically used for the two hot conductors per NEC Article 200 color coding conventions?

A.Black and red

B.Black and white

C.White and green

D.Red and green

Explanation: For 240V single-phase wiring, both ungrounded (hot) conductors are typically black and red. White is the grounded (neutral) conductor color, and green or bare is reserved for the equipment grounding conductor per NEC Article 200 and 250.

7NEC Article 430 requires that a submersible pump motor be protected by an overload device sized at no more than what percentage of the motor's full-load current for a single-phase motor with a service factor of 1.15 or greater?

A.125%

B.115%

C.100%

D.140%

Explanation: Per NEC Article 430.32, a motor with a service factor of 1.15 or greater may have its overload protection sized at up to 125% of the motor's full-load current. This provides thermal protection while allowing for normal starting current variations.

8Which type of motor starting method reduces inrush current and mechanical stress during startup for large three-phase submersible pump motors?

A.Soft starter or Variable Frequency Drive (VFD)

B.Across-the-line (full voltage) starting

C.Capacitor-start only

D.Manual starting with a drum switch

Explanation: Soft starters and VFDs ramp up voltage (soft starter) or frequency and voltage (VFD) gradually during startup, limiting inrush current to 200-400% of full-load current instead of the typical 600-700% with across-the-line starting. This reduces stress on motor windings, pump impellers, and well piping.

9A single-phase, capacitor-start submersible pump motor fails to start but hums loudly. The most likely electrical cause is:

A.A failed start capacitor

B.Low system voltage (brownout condition)

C.An open circuit in the run winding

D.Excessive back pressure from a closed check valve

Explanation: A failed (open or shorted) start capacitor prevents the phase shift needed to create starting torque in a single-phase motor. The motor hums on the run winding but cannot develop enough torque to overcome inertia. Replacing the start capacitor restores normal startup.

10GFCI protection is required by the NEC for receptacles and equipment in which of the following pump installation locations?

A.Crawl spaces and outdoor locations

B.Finished living areas above grade only

C.Only in locations with standing water more than 6 inches deep

D.Only when the voltage exceeds 150V to ground

Explanation: NEC Article 210.8 requires GFCI protection for receptacles and equipment in crawl spaces, outdoors, garages, unfinished basements, and near water sources. Pump control panels in these locations must be GFCI protected to prevent electric shock in damp environments.

About the NGWA CPI Exam

National certification for professional pump installers. The NGWA CPI is the only national voluntary credential for groundwater pump installation professionals, covering pump sizing, installation, electrical systems, and troubleshooting.

Questions

50 scored questions

Time Limit

1 hour per exam

Passing Score

70%

Exam Fee

$75 per exam (NGWA via PSI Services)

NGWA CPI Exam Content Outline

~25%

Pump Selection & Sizing

TDH, pump curves, BEP, specific capacity, friction loss

~25%

Pump Installation

Drop pipe, torque arrestors, pitless adapters, check valves, grouting

~20%

Electrical Systems

NEC Article 430, motor starting, GFCI, VFDs, control boxes

~15%

Pressure Systems

Pressure tanks, precharge, drawdown, pressure switches

~10%

Water Quality

Iron, hardness, pH, manganese, sand abrasion

~5%

Troubleshooting & Certification

Diagnostics, low-yield wells, NGWA program requirements

How to Pass the NGWA CPI Exam

What You Need to Know

Passing score: 70%
Exam length: 50 questions
Time limit: 1 hour per exam
Exam fee: $75 per exam

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

NGWA CPI Study Tips from Top Performers

1Master TDH calculation — add static water level, friction losses in drop pipe, and discharge pressure head (psi × 2.31 = feet)

2Memorize the precharge rule: precharge = cut-in pressure minus 2 psi, always set with pump off and system pressure bled

3Learn NEC Article 430 thoroughly — branch circuit ampacity is 125% of FLA, overload protection at 125% for SF 1.15+ motors

4Know the check valve rule: one intermediate check valve every ~200 ft of vertical rise to prevent water hammer

5Understand ASSE 1018 pitless adapter requirements — installed below local frost depth, O-ring sealed, sanitary well exit

6Study VFD constant-pressure systems: pressure transducer feedback loop, minimum speed for motor cooling, sleep mode

7Review water quality thresholds: iron SMCL 0.3 mg/L, manganese SMCL 0.05 mg/L, hardness >10.5 gpg = very hard

Frequently Asked Questions

How many exams must I pass to earn the NGWA CPI?

Two exams are required: (1) the water systems general exam and (2) at least one specialized pump exam — Exam K for water systems less than 100 gpm or Exam L for 100 gpm or more. Both must be passed within a 12-month period with scores of 70% or better. Each exam has 50 questions and a 1-hour time limit.

What is the cost of the NGWA CPI exams?

Each exam costs $75 regardless of NGWA membership status, for a total of $150 for the two required exams. Exams are administered by PSI Services and can be scheduled online at test-takers.psiexams.com/ngwa or by calling (855) 579-4642.

What experience is required before applying for the CPI?

Applicants must be at least 20 years old and have a minimum of 24 consecutive months (2 years) of full-time pump installation experience. Two professional references (not from your current employer), a signed agreement form, and a current-year affidavit are also required.

What topics are most important for the NGWA CPI exam?

Focus heavily on pump selection and sizing (TDH calculation, pump curves, BEP, friction loss in drop pipe), installation best practices (torque arrestors, pitless adapters per ASSE 1018, check valves every 200 ft, well sealing/grouting), electrical systems (NEC Article 430, GFCI requirements, motor starting methods, 240V wiring), and pressure tank operation (precharge = cut-in minus 2 psi, short cycling causes and fixes).

How often must I renew my CPI certification?

CPI certification must be renewed annually by December 31. Annual renewal requires 7 continuing education points (CEPs), a signed affidavit (no pending legal actions, state licenses maintained), and the renewal fee. CEPs can be earned through NGWA workshops, webinars, safety training, and industry events.

Is the NGWA CPI required to install pumps in my state?

No. The NGWA CPI is a voluntary national professional certification — it is not a state-issued license. Many states have their own mandatory pump installer licensing requirements. The CPI complements state licensing by demonstrating nationally recognized professional competence and knowledge, which can be valuable for employment, competitive bidding, and customer trust.