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NGWA CPI practice questions

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Question 1Pump systems and installation (draft domain pending official outline)

A residential well pump system uses a bladder-type pressure tank. What is the primary function of this tank in the system?

  1. It provides a reserve of water for fire suppression during power outages
  2. It cools the pump motor by circulating water around the windings
  3. It stores water under pressure to reduce pump cycling and maintain system pressure between pump runs Correct answer.
  4. It filters sediment and iron from the water before it reaches the fixtures

Explanation

A pressure tank uses a captive air charge to store water under pressure, so the pump runs less frequently and the system maintains pressure between cycles. The air precharge and tank drawdown determine how much water is available before the pump restarts. Filtration, fire reserve, and motor cooling are separate functions not performed by a standard bladder tank.

Question 2Pump systems and installation (draft domain pending official outline)

A submersible pump is being set in a well. Which installation practice best protects the pump motor from overheating during operation?

  1. Wrapping the motor in insulation to hold heat near the windings
  2. Setting the pump so the motor is above the static water level
  3. Setting the pump so the motor section is below the well's pumping level and in the flow stream Correct answer.
  4. Installing a check valve directly at the motor discharge to trap water

Explanation

Submersible motors shed heat to the water moving past the motor housing, so the motor must stay submerged below the pumping level during operation. If the water level drops below the motor, cooling is lost and the motor can overheat and fail. Insulation and trapped water do not provide the required continuous flow of cool water.

Question 3Pump systems and installation (draft domain pending official outline)

A pressure switch on a jet pump system is set to cut in at 30 psi and cut out at 50 psi. What does the 20 psi difference represent?

  1. The pressure switch differential Correct answer.
  2. The pressure tank precharge setting
  3. The pump's maximum shutoff head
  4. The system's friction loss allowance

Explanation

The difference between the cut-in and cut-out pressures is the switch differential, here 20 psi. It determines the pressure band the system operates within and influences tank drawdown. It is not the tank precharge, the pump's shutoff head, or a friction allowance.

Question 4Pump systems and installation (draft domain pending official outline)

A pitless adapter is installed on a well. What is its main purpose?

  1. To provide a below-frost-line connection that carries water through the casing to the service line Correct answer.
  2. To anchor the drop pipe to the well cap
  3. To measure the water level in the well during pumping tests
  4. To disinfect water as it leaves the well

Explanation

A pitless adapter makes the connection through the well casing below the frost line, allowing the service line to leave the well without a pit. This protects the discharge line from freezing and keeps the well sanitary. It does not measure level, disinfect water, or serve as the drop pipe anchor.

Question 5Pump systems and installation (draft domain pending official outline)

A pump installer is selecting a check valve for a submersible pump installation. Where should the primary check valve be located?

  1. Directly above the pump discharge Correct answer.
  2. At the service line where it enters the house
  3. At the pressure tank inlet
  4. On the suction side of the pressure switch

Explanation

The primary check valve belongs directly above the pump discharge to hold water in the drop pipe and prevent backspin when the pump stops. Additional check valves may be used on deep settings, but the first one is at the pump. Locating it only at the tank or house entry leaves the drop pipe to drain back.

Question 6Pump systems and installation (draft domain pending official outline)

A shallow-well jet pump loses its prime after sitting idle. Which condition most commonly causes this?

  1. The pressure switch differential is too wide
  2. The pressure tank precharge is too high
  3. The pump motor is wired for the wrong voltage
  4. A leak in the suction line allows air to enter Correct answer.

Explanation

Shallow-well jet pumps pull water by suction, so any air leak in the suction pipe, foot valve, or fittings breaks the vacuum and lets the pump lose prime. A failing foot valve that does not hold water also causes this. Tank precharge, switch differential, and voltage do not admit air into the suction line.

Question 7Pump systems and installation (draft domain pending official outline)

A constant pressure system uses a variable frequency drive (VFD). What advantage does this provide compared with a standard pressure switch system?

  1. It varies pump speed to hold a steadier pressure and reduce cycling Correct answer.
  2. It removes the need for a check valve on the discharge
  3. It increases the pump's maximum flow beyond its rated curve
  4. It eliminates the need for any pressure tank in the system

Explanation

A VFD changes motor speed to match demand, holding a more constant discharge pressure and reducing start-stop cycling. A small tank is still normally required for low-flow stability and to absorb pressure surges. A VFD does not increase the pump's hydraulic capability or replace the check valve.

Question 8Pump systems and installation (draft domain pending official outline)

A pump is described as having a shutoff head of 200 feet. What does this value mean?

  1. The pump produces 200 feet of head at zero flow Correct answer.
  2. The pump's motor draws 200 watts at full speed
  3. The pump can lift water from a depth of 200 feet at rated flow
  4. The pump delivers its maximum flow at 200 feet of lift

Explanation

Shutoff head is the maximum head a pump can generate when the discharge is closed and flow is zero. It is the point where the pump curve crosses the zero-flow axis. It is not a flow rating, a power rating, or the maximum suction lift.

Question 9Pump systems and installation (draft domain pending official outline)

A submersible pump is installed in a well with a static water level of 60 feet and a pumping level of 120 feet. The installer wants the pump set at a depth that avoids drawdown problems. Which setting depth is most appropriate?

  1. Set the pump at 100 feet, above the pumping level
  2. Set the pump resting on the well bottom for maximum submergence
  3. Set the pump at 65 feet so it stays near the static level
  4. Set the pump well below the pumping level while staying above the well bottom Correct answer.

Explanation

The pump should be set below the pumping level so the motor stays submerged and the intake does not draw air during drawdown, while leaving clearance above the well bottom. Setting near the static level risks the pump being exposed as the level drops. Resting on the bottom risks pulling sediment and sand.

Question 10Pump systems and installation (draft domain pending official outline)

A pressure tank has a 40 psi precharge and the pressure switch is set at 30/50 psi. What symptom will this mismatch most likely cause?

  1. The pump will run continuously at low pressure
  2. The pump will short-cycle and little drawdown will be available Correct answer.
  3. The tank will overfill with water and rupture
  4. The pressure switch will fail to cut out at 50 psi

Explanation

The tank precharge should be set about 2 psi below the cut-in pressure, so with a 30 psi cut-in the precharge should be near 28 psi. A 40 psi precharge means the tank is already partly filled with water before the pump starts, leaving very little drawdown and causing rapid cycling. It does not cause continuous running or switch failure.

Question 11Pump systems and installation (draft domain pending official outline)

A two-wire submersible pump motor is being replaced. How does a two-wire motor differ from a three-wire motor in its starting arrangement?

  1. The two-wire motor has built-in starting components and needs no control box Correct answer.
  2. The two-wire motor uses a separate start winding energized by the pressure switch
  3. The two-wire motor requires an external control box with a start capacitor
  4. The two-wire motor relies on a mechanical centrifugal switch at the surface

Explanation

Two-wire submersible motors contain the start winding, capacitor, and overload protection inside the motor, so no surface control box is needed. Three-wire motors use an external control box with starting components. Neither type uses a pressure switch to start the winding or a surface centrifugal switch.

Question 12Pump systems and installation (draft domain pending official outline)

A deep-well jet pump uses a two-pipe (packer) system. What is the role of the second pipe in this arrangement?

  1. It carries the suction line from the well to the pressure tank
  2. It provides a vent to release accumulated air from the casing
  3. It supplies electrical conduit to the motor
  4. It returns a portion of the pumped water to the ejector to drive the jet Correct answer.

Explanation

In a two-pipe deep-well jet system, one pipe delivers pressurized water down to the ejector and the second pipe returns the mixed water up to the surface. The driving water powers the venturi that lifts additional water. The second pipe is not a vent, conduit, or suction line to the tank.

Question 13Pump systems and installation (draft domain pending official outline)

A pump installer needs to size a pressure tank for a system with a 40/60 psi switch setting. Which precharge value is most appropriate?

  1. 20 psi
  2. 50 psi
  3. 38 psi Correct answer.
  4. 60 psi

Explanation

Precharge is normally set about 2 psi below the cut-in pressure, so with a 40 psi cut-in the correct precharge is approximately 38 psi. Setting it at the cut-in or higher reduces drawdown and causes short cycling. A much lower precharge wastes tank capacity.

Question 14Pump systems and installation (draft domain pending official outline)

A submersible pump's drop pipe is being assembled with threaded joints. Which practice best protects the joint and the pump?

  1. Use a pipe wrench on the pump body to hold it while tightening the pipe
  2. Overtighten the joints to prevent any chance of leakage
  3. Support the drop pipe with a pipe vise or hoist and apply pipe dope or tape to the male threads Correct answer.
  4. Use no sealant so the joints can be disassembled easily

Explanation

The drop pipe should be held with a proper vise or hoist while joints are made up, and the male threads should be sealed with approved pipe dope or tape. Holding the pump body with a wrench can twist and damage the motor and pump. Overtightening can crack fittings, and omitting sealant invites leaks and air entry.

Question 15Pump systems and installation (draft domain pending official outline)

A pump system's pressure gauge shows pressure rising to the cut-out point but the pump continues to run and the pressure keeps climbing slowly. Which cause is most likely?

  1. The pressure tank bladder is ruptured
  2. The pump is cavitating due to low suction
  3. The pressure switch is stuck closed and not responding to pressure Correct answer.
  4. The check valve is stuck open and allowing backflow

Explanation

If pressure rises past the cut-out setting but the pump keeps running, the switch is not opening to interrupt power. A stuck or misadjusted switch keeps the pump energized. A stuck check valve, a ruptured bladder, or cavitation would produce different symptoms such as rapid cycling, waterlogged tank, or noise and low flow.

Question 16Pump systems and installation (draft domain pending official outline)

A pump installer is choosing a pump for a system requiring 15 gpm at 180 feet of total head. The pump curve shows 15 gpm at 180 feet near the middle of the curve. Why is selecting a point near the middle of the curve preferable to selecting a point at the curve's end?

  1. Operating near the middle of the curve keeps the pump away from the extremes where efficiency drops and wear increases Correct answer.
  2. The pump motor draws maximum current at the middle of the curve
  3. The middle of the curve corresponds to the pump's shutoff head
  4. The pump is less efficient at the middle of the curve

Explanation

Pump curves are most efficient near their middle, and operating at the far ends of the curve can cause reduced efficiency, higher vibration, or motor overload. Selecting a duty point near the best efficiency range promotes longer pump life. Shutoff is at zero flow, not the middle, and current draw is highest near maximum flow.

Question 17Pump systems and installation (draft domain pending official outline)

A submersible pump installation requires the electrical disconnect to be located where?

  1. At the pressure tank only if the tank is indoors
  2. At the utility meter pedestal regardless of distance
  3. Within sight of and readily accessible from the pump controller location Correct answer.
  4. Inside the well casing near the pump

Explanation

Electrical codes require a disconnecting means that is within sight of and readily accessible from the pump controller or motor location so the circuit can be de-energized for service. Placing it inside the well casing or remote from the controller defeats that safety purpose. The meter pedestal is not a substitute for a service disconnect at the controller.

Question 18Pump systems and installation (draft domain pending official outline)

A pump installer is wiring a three-wire submersible pump. What is the purpose of the control box in this circuit?

  1. It regulates the water pressure in the tank
  2. It provides a check valve function on the discharge
  3. It converts single-phase power to three-phase power
  4. It houses the starting capacitor and overload protection for the motor Correct answer.

Explanation

A three-wire submersible motor uses a surface-mounted control box containing the starting capacitor, relay, and overload protection needed to start and protect the motor. It does not convert phases, regulate pressure, or perform a check valve function. Two-wire motors have these components built into the motor.

Question 19Pump systems and installation (draft domain pending official outline)

A homeowner reports that a submersible pump runs briefly, then the overload trips, and it restarts after cooling. Which condition is the most likely cause?

  1. The pressure gauge is reading incorrectly
  2. The pressure tank precharge is too low
  3. The check valve is leaking slightly
  4. The pump is running dry or the motor is overheating due to low water level Correct answer.

Explanation

Overload tripping that resets after cooling suggests the motor is overheating, often because the water level has dropped below the motor or the pump is running dry. The thermal overload protects the motor by cutting power until it cools. Tank precharge, a slightly leaking check valve, and a faulty gauge do not cause overload trips.

Question 20Pump systems and installation (draft domain pending official outline)

A well produces sand and fine sediment that is damaging the pump. Which installation approach best reduces this problem?

  1. Increase the pump speed to flush the sand through the system
  2. Install a sand separator or screen ahead of the pump intake and set the pump above the sand-producing zone Correct answer.
  3. Set the pump deeper into the producing zone to maximize submergence
  4. Set the pump higher in the well so it draws from clearer water near the top

Explanation

Sand and sediment problems are best managed by keeping the pump intake above the sand-producing interval and using a sand separator or screen to protect the pump. Setting deeper into the producing zone draws more sand, and increasing speed worsens abrasion. Raising the pump alone may not solve the problem if the sediment is suspended.

Question 21Pump systems and installation (draft domain pending official outline)

A pump installation uses a torque arrestor on the submersible pump. What does this component do?

  1. It filters sand from the water before it enters the pump
  2. It limits the starting torque reaction of the motor to protect the drop pipe and wiring Correct answer.
  3. It increases the pump's discharge pressure
  4. It serves as the primary check valve

Explanation

A torque arrestor grips the casing and absorbs the twisting reaction each time the motor starts, reducing stress on the drop pipe, fittings, and cable. It does not affect discharge pressure, filter sediment, or act as a check valve. It is especially useful on deep settings and larger motors.

Question 22Pump systems and installation (draft domain pending official outline)

A jet pump is installed with the ejector at the surface (shallow-well configuration). What limits the maximum depth from which this arrangement can lift water?

  1. The pressure switch cut-out setting
  2. The pressure tank size
  3. The pump motor horsepower rating only
  4. Atmospheric pressure, practically limited to about 25 feet of suction lift Correct answer.

Explanation

A surface-mounted ejector relies on suction, which is limited by atmospheric pressure to a theoretical maximum of about 34 feet and practically about 25 feet. Beyond that, the pump cannot lift water regardless of motor horsepower. Tank size and switch settings do not change the suction-lift limit.

Question 23Pump systems and installation (draft domain pending official outline)

A submersible pump is being installed in a well with a casing diameter of 6 inches. The pump has a 4-inch motor. Which consideration is most important when selecting the pump and cable for this installation?

  1. Choosing the largest possible cable to fill the annular space
  2. Ensuring adequate clearance around the pump for water flow to cool the motor and accommodate the cable Correct answer.
  3. Selecting a pressure tank with the highest available precharge
  4. Setting the pump so it rests against the casing wall for stability

Explanation

In a 6-inch casing with a 4-inch pump, the annular clearance must allow water to flow past the motor for cooling and provide room for the cable and safety rope. A pump that fits too tightly can overheat and damage the cable. Cable size is governed by voltage drop and ampacity, not by filling space, and the pump should hang centered, not against the casing.

Question 24Pump systems and installation (draft domain pending official outline)

A pump system is experiencing water hammer each time the pump shuts off. Which combination of causes is most likely?

  1. A pressure switch differential that is too narrow
  2. A pump set too deep in the well
  3. A failed check valve allowing backflow combined with inadequate surge control Correct answer.
  4. A pressure tank that is too large for the system

Explanation

Water hammer at shutdown commonly results from a check valve that slams shut or allows reverse flow, combined with no means to absorb the surge, such as a properly charged tank or surge arrestor. A properly functioning check valve and charged tank cushion the deceleration. Oversized tanks, narrow differentials, and pump depth are not the primary causes.

Question 25Pump systems and installation (draft domain pending official outline)

An installer is evaluating a well with a static water level of 20 feet, a pumping level of 90 feet, and a recovery rate that is slow relative to the pump's capacity. What is the most significant risk in sizing the pump to the well's full capacity?

  1. The pump will produce too much pressure and damage the pressure tank
  2. The check valve will fail from excessive flow
  3. The pump will draw the water level down to the pump intake and run dry, causing motor damage Correct answer.
  4. The pressure switch will not sense pressure changes

Explanation

When the well's recovery is slower than the pump's capacity, pumping at full rate draws the water level down toward the intake. Once the level reaches the pump, the pump runs dry, loses cooling, and the motor can be damaged. The correct approach is to size the pump to the well's sustainable yield, not its maximum capacity.

Question 26Pump systems and installation (draft domain pending official outline)

A submersible pump is being set in a well. Which component is installed on the discharge piping just above the pump to prevent the pump from unscrewing and dropping if the motor starts against a stuck impeller?

  1. A safety rope
  2. A check valve
  3. A torque arrestor Correct answer.
  4. A flow sleeve

Explanation

A torque arrestor grips the casing and absorbs the reactive torque that occurs at motor start, which otherwise can spin the pump and loosen threaded joints. It is mounted on the pump discharge, above the pump body, and does not control flow direction.

Question 27Pump systems and installation (draft domain pending official outline)

What is the primary function of a check valve installed directly above a submersible pump?

  1. To vent air that accumulates in the drop pipe
  2. To regulate the discharge pressure to the tank setting
  3. To protect the motor from overload during startup
  4. To keep the drop pipe and pressure tank from losing their water and pressure when the pump stops Correct answer.

Explanation

The check valve closes when the pump stops so the column of water in the drop pipe does not drain back into the well. This holds pressure in the system and prevents the pump from having to re-prime and restart against a dry column.

Question 28Pump systems and installation (draft domain pending official outline)

A pump installer is selecting a pitless adapter for a well. What is the main purpose of this fitting?

  1. It filters sand and grit from the water before it enters the pump
  2. It increases the discharge pressure before the water reaches the pressure tank
  3. It provides the watertight connection through the casing below the frost line and allows the drop pipe to be removed Correct answer.
  4. It anchors the pump in the well to prevent vertical movement

Explanation

A pitless adapter makes a watertight, frost-free connection through the well casing and lets the drop pipe and pump be pulled without excavating the service line. It is a mechanical connection, not a pressure or filtration device.

Question 29Pump systems and installation (draft domain pending official outline)

A pressure switch on a residential pump system is rated for 30/50 psi. What do these two numbers represent?

  1. The low and high limits of the relief valve
  2. The minimum and maximum tank precharge values
  3. The working and burst pressure ratings of the drop pipe
  4. The cut-in and cut-out pressures at which the pump starts and stops Correct answer.

Explanation

The first number is the cut-in pressure at which the pump starts and the second is the cut-out pressure at which it stops. The differential between them, 20 psi here, determines how much water the tank can draw down between cycles.

Question 30Pump systems and installation (draft domain pending official outline)

Which measurement describes the vertical distance from the pump's discharge to the highest point the water must be lifted in a system?

  1. Net positive suction head
  2. Static head Correct answer.
  3. Total dynamic head
  4. Friction head

Explanation

Static head is the vertical lift only, independent of flow. Total dynamic head adds friction and velocity losses to static head, which is why the two differ once water is moving.

Question 31Pump systems and installation (draft domain pending official outline)

A submersible pump motor must be installed so that water flows past it during operation. Why is this cooling flow important?

  1. It reduces the friction loss in the drop pipe
  2. It keeps the motor windings within their temperature rating so the motor is not damaged Correct answer.
  3. It prevents the check valve from sticking closed
  4. It keeps the pressure switch from chattering

Explanation

Submersible motors rely on the moving well water to carry heat away from the motor housing. If the pump is set below the pumping level or in a shroud with insufficient flow, the motor can overheat and fail.

Question 32Pump systems and installation (draft domain pending official outline)

A pump installer is connecting a pressure tank to a system with a 30/50 psi switch. Where should the tank be connected relative to the pressure switch?

  1. On the suction side of the pump between the well and the pump intake
  2. On the discharge side of the pump, downstream of the check valve and on the same line as the pressure switch Correct answer.
  3. Directly on the well casing above the pitless adapter
  4. Between the check valve and the pump discharge

Explanation

The tank and pressure switch must sense the same system pressure, so both belong on the discharge side downstream of the check valve. Placing the tank on the suction side would expose it to vacuum and would not store pressurized water.

Question 33Pump systems and installation (draft domain pending official outline)

Which device is used to protect a submersible pump motor against running dry when the well water level drops below the pump intake?

  1. A pressure relief valve
  2. A bypass line
  3. A low-water cutoff or pump protector Correct answer.
  4. A flow restrictor

Explanation

A low-water cutoff senses the loss of flow or pressure and shuts the pump off before the motor overheats from running dry. It restarts the pump only after water level recovers, protecting the motor.

Question 34Pump systems and installation (draft domain pending official outline)

A pump installer is calculating total dynamic head for a system with 80 feet of static lift, 12 feet of friction loss, and a required discharge pressure of 30 psi at the outlet. Approximately what total dynamic head must the pump produce?

  1. 122 feet
  2. 201 feet
  3. 161 feet Correct answer.
  4. 92 feet

Explanation

Convert the discharge pressure to head: 30 psi times 2.31 equals about 69 feet. Add static lift of 80 feet and friction of 12 feet to get roughly 161 feet of total dynamic head.

Question 35Pump systems and installation (draft domain pending official outline)

An installer is setting a submersible pump in a well with a pumping level of 100 feet. To keep the pump safely submerged and cooled, the pump intake should be set:

  1. Exactly at the pumping level
  2. Above the pumping level to reduce lift
  3. Well below the pumping level, allowing for drawdown and seasonal variation Correct answer.
  4. At the static water level

Explanation

The pump must stay submerged even at the lowest pumping level, so it is set below that level with margin for drawdown and seasonal changes. Setting it at or above the pumping level risks exposing the intake and overheating the motor.

Question 36Pump systems and installation (draft domain pending official outline)

A shallow-well jet pump can lift water only about 25 feet because of atmospheric pressure limits. What is the practical consequence for an installer evaluating a well with a 40-foot depth to water?

  1. The jet pump will work if the ejector is moved to the surface
  2. The jet pump will work if the suction pipe is increased in diameter
  3. A shallow-well jet pump is not suitable and a deep-well jet or submersible should be used Correct answer.
  4. The jet pump will work if a larger pressure tank is installed

Explanation

Atmospheric pressure can support only about 33 feet of water column, and practical suction lift is less after losses. A 40-foot depth to water exceeds shallow-well jet capability, so a deep-well jet with a down-hole ejector or a submersible pump is required.

Question 37Pump systems and installation (draft domain pending official outline)

During a pump test, the pressure gauge reads 50 psi at the pump discharge. What head in feet does this pressure represent?

  1. 21.7 feet
  2. 50 feet
  3. 115.5 feet Correct answer.
  4. 231 feet

Explanation

One psi of pressure corresponds to about 2.31 feet of water head. Multiplying 50 psi by 2.31 gives approximately 115.5 feet of head.

Question 38Pump systems and installation (draft domain pending official outline)

An installer is choosing between a 4-inch and a 6-inch submersible pump for a well with a 6-inch casing. Which consideration is most important?

  1. The larger pump requires no check valve
  2. The pump outside diameter must leave adequate clearance in the casing for cooling flow and installation Correct answer.
  3. The smaller pump cannot be used with a pitless adapter
  4. The larger pump always produces higher pressure

Explanation

A pump must fit the casing with enough annular clearance for water to flow past the motor for cooling and for the assembly to be lowered without binding. A pump too close to casing size risks overheating and installation problems.

Question 39Pump systems and installation (draft domain pending official outline)

A pump installer observes that the amperage draw of a submersible motor is higher than the nameplate value while the pump is running. Which condition is the most likely cause?

  1. The motor is running below its rated voltage Correct answer.
  2. The pump is running at shutoff head with low flow
  3. The check valve is fully open
  4. The well water level is higher than expected

Explanation

Low voltage causes a motor to draw more current to deliver the same power, which can trip overloads and damage windings. High amperage should prompt a voltage check at the motor leads under load.

Question 40Pump systems and installation (draft domain pending official outline)

A pump system short-cycles, turning on and off rapidly. Which cause should the installer check first?

  1. A check valve that is fully seated
  2. A pressure switch set with a wide differential
  3. A pump set too deep in the well
  4. A failed or waterlogged pressure tank Correct answer.

Explanation

A waterlogged tank has lost its air charge and cannot store water, so pressure rises and falls almost instantly and the switch cycles the pump. Checking tank precharge and bladder condition is the first diagnostic step.

Question 41Pump systems and installation (draft domain pending official outline)

A submersible pump is installed with a galvanized steel drop pipe in a well with corrosive water. What is the main risk of this material choice?

  1. The pipe will not support the pump weight
  2. The pipe will collapse under pressure
  3. The pipe will increase the pump's flow rate
  4. Corrosion and scale can weaken the pipe and contaminate the water Correct answer.

Explanation

Galvanized steel can corrode and scale in aggressive water, weakening the pipe and introducing iron and zinc into the supply. In corrosive conditions, thermoplastic drop pipe or a corrosion-resistant material is preferred.

Question 42Pump systems and installation (draft domain pending official outline)

A jet pump on a deep-well two-pipe system is losing prime repeatedly. Which condition is the most likely cause?

  1. The foot valve or check valve is leaking Correct answer.
  2. The ejector is installed too deep
  3. The pump motor is oversized
  4. The pressure tank precharge is too high

Explanation

A leaking foot or check valve allows water in the suction and drive lines to drain back, so the pump loses prime when it stops. A two-pipe deep-well system depends on these valves to hold the water column.

Question 43Pump systems and installation (draft domain pending official outline)

An installer is wiring a submersible pump and needs to bond the metal well casing and the pump motor frame. Why is this bonding required?

  1. To increase the motor's starting torque
  2. To reduce the pump's power consumption
  3. To keep the pressure switch from arcing
  4. To provide a low-impedance path to ground so fault current trips the breaker and shock hazard is reduced Correct answer.

Explanation

Bonding metal parts creates a low-impedance fault path so a ground fault will trip the overcurrent device instead of energizing the casing. It also equalizes potential to protect people from shock.

Question 44Pump systems and installation (draft domain pending official outline)

A pump delivers 20 gpm at 150 feet of head on its published curve. The system requires 20 gpm at 170 feet. What does this indicate about the pump selection?

  1. The pump will operate at a higher flow than 20 gpm
  2. The pump is oversized and will short-cycle
  3. The pump is undersized for the required head and will not meet demand Correct answer.
  4. The pump is correctly sized because flow matches

Explanation

The pump curve shows the pump can produce only 150 feet at 20 gpm, which is less than the 170 feet required. The operating point will fall at a lower flow, so the pump cannot meet the design condition.

Question 45Pump systems and installation (draft domain pending official outline)

A pressure tank on a 40/60 psi system has a precharge of 55 psi. What effect will this have on system operation?

  1. The pump will not start at the cut-in pressure
  2. The pressure switch will fail to cut out
  3. The tank will store less water and the pump will cycle more often Correct answer.
  4. The tank will store more water and the pump will run longer

Explanation

Precharge should be about 2 psi below cut-in, so 38 psi for a 40 psi setting. A 55 psi precharge is above cut-in, so the tank accepts very little water before the pump starts, reducing drawdown and increasing cycling.

Question 46Pump systems and installation (draft domain pending official outline)

A pump installer is calculating the drawdown of a pressure tank. The system has a 40/60 psi switch and a tank with a 38 psi precharge. Which factor most directly determines the volume of usable water?

  1. The tank's total volume and the pressure differential between cut-in and cut-out Correct answer.
  2. The diameter of the drop pipe
  3. The pump's shutoff head
  4. The depth of the well

Explanation

Usable drawdown depends on tank size and the pressure range over which the system operates, since gas compression between cut-in and cut-out determines how much water enters. Larger tanks or wider differentials yield more drawdown.

Question 47Pump systems and installation (draft domain pending official outline)

A submersible pump in a 6-inch well is set in a shroud because the well produces water from a zone below the pump intake. What does the shroud accomplish?

  1. It increases the pump's discharge pressure
  2. It forces water to flow past the motor for cooling from the intake end Correct answer.
  3. It anchors the pump to the casing
  4. It filters sediment before it enters the pump

Explanation

A shroud creates an annular flow path so water is drawn from below and passes over the motor before entering the intake, providing cooling even when the pump is set below the producing zone. It does not add pressure or filter water.

Question 48Pump systems and installation (draft domain pending official outline)

An installer is evaluating a well with a static water level of 20 feet, a pumping level of 90 feet, and a recovery rate of 5 gpm. The pump selected delivers 15 gpm. What is the most significant concern?

  1. The static water level is too shallow for a submersible pump
  2. The pump will draw the well down faster than it recovers and may run dry Correct answer.
  3. The pumping level is too deep for the pump to lift water
  4. The recovery rate is irrelevant to pump selection

Explanation

With a pump rate of 15 gpm and a recovery of only 5 gpm, the well cannot sustain the pump and the water level will continue to fall during operation. This risks exposing the pump and requires low-water protection or a smaller pump.

Question 49Pump systems and installation (draft domain pending official outline)

A pump system experiences pressure surges when the pump shuts off. Which combination of causes is most likely?

  1. A pump set too deep and an oversized drop pipe
  2. A pressure switch with a narrow differential and a large tank
  3. A missing or failed check valve and a tank with insufficient air charge Correct answer.
  4. A low-water cutoff and a foot valve that is fully open

Explanation

Water hammer on shutdown often results from reverse flow that is suddenly stopped by a check valve, or from a tank that cannot absorb the pressure spike. A failed check valve or a waterlogged tank both allow abrupt pressure changes.

Question 50Pump systems and installation (draft domain pending official outline)

A submersible pump motor is rated for 230 volts and the installer measures 208 volts at the motor leads under load. What is the most appropriate action?

  1. Check the wire size and connections, and consult the motor's acceptable voltage range before operating Correct answer.
  2. Operate the pump as is because 208 volts is within tolerance
  3. Increase the pressure switch setting to compensate
  4. Replace the motor with a 115-volt unit

Explanation

A 208-volt reading on a 230-volt rated motor may be outside the motor's acceptable range and can cause overheating and high amperage. The installer should verify voltage drop, wire sizing, and connections and confirm the motor's rated tolerance before running it.