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AK Plumber practice questions

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Question 1General Plumbing Regulations, Definitions, and Administration

Under the Alaska plumbing regulations, which individual is authorized to obtain a plumbing permit for work on a residential property they own and occupy?

  1. A plumbing supply retailer selling the fixtures
  2. An unlicensed handyman hired by the owner
  3. A licensed journeyman plumber employed by a contractor
  4. The property owner who will personally perform the work Correct answer.

Explanation

Alaska regulations allow an owner-occupant of a single-family residence to obtain a permit and perform plumbing work on that dwelling themselves. Contractors and journeymen must work under an appropriate licensed entity, and retailers or unlicensed helpers cannot pull permits.

Question 2General Plumbing Regulations, Definitions, and Administration

In Alaska, plumbing work that requires a permit must generally be inspected at what point before being concealed?

  1. Within 30 days after occupancy
  2. Only after the entire project is finished
  3. At the discretion of the supply house
  4. Before the work is covered or concealed Correct answer.

Explanation

Regulations require rough-in plumbing to be inspected and approved before it is concealed by walls, floors, or ceilings. Concealing work before inspection removes the ability to verify compliance.

Question 3General Plumbing Regulations, Definitions, and Administration

A plumbing contractor licensed in Alaska wishes to perform plumbing work in a different state. What is the general rule regarding that contractor's Alaska license?

  1. It automatically authorizes work in any state
  2. It must be surrendered before working elsewhere
  3. It converts into a national certification
  4. It has no force outside Alaska's jurisdiction Correct answer.

Explanation

A state-issued plumbing license is valid only within the jurisdiction that issued it. Working in another state requires meeting that state's own licensing requirements.

Question 4General Plumbing Regulations, Definitions, and Administration

Which document typically defines the scope, materials, and standards for a specific plumbing installation on a construction project?

  1. The invoice from the supply vendor
  2. The approved construction drawings and specifications Correct answer.
  3. The plumbing code book alone
  4. The manufacturer's warranty card

Explanation

Approved drawings and specifications establish the specific scope, materials, and standards for the project and supplement the adopted code. The code sets minimum requirements, while plans define the particular installation.

Question 5General Plumbing Regulations, Definitions, and Administration

What does the term 'potable water' mean as used in plumbing regulations?

  1. Water stored in a nonpressurized tank
  2. Water that has been chemically treated for boilers
  3. Water free from contaminants at levels safe for human consumption Correct answer.
  4. Water reclaimed from laundry discharge

Explanation

Potable water is water that meets health standards for drinking and domestic use, free of contaminants at harmful levels. It is distinct from boiler water, graywater, or stored water that may not meet those standards.

Question 6General Plumbing Regulations, Definitions, and Administration

In plumbing terminology, what is a 'fixture unit' used to express?

  1. The physical weight of a fixture in pounds
  2. The retail price of a fixture
  3. The number of fixtures allowed per bathroom
  4. The load-producing effect of a fixture on the drainage system Correct answer.

Explanation

A fixture unit is a measure of the probable discharge load a fixture places on the drainage and venting system. It allows sizing of pipes based on expected flow rather than physical dimensions.

Question 7General Plumbing Regulations, Definitions, and Administration

A homeowner hires a licensed plumbing contractor to replace a water heater. Who is responsible for ensuring the required permit is obtained before work begins?

  1. The water heater manufacturer
  2. The utility providing the gas
  3. The plumbing contractor performing the work Correct answer.
  4. The homeowner alone

Explanation

The licensed contractor performing permitted work is responsible for obtaining the required permit before beginning the job. This ensures the work is inspected and compliant.

Question 8General Plumbing Regulations, Definitions, and Administration

An inspector finds that a contractor began installing drain lines without first obtaining the required permit. What is the most appropriate regulatory consequence?

  1. The work is automatically approved because it was completed
  2. The contractor may be subject to stop-work orders, fees, or disciplinary action Correct answer.
  3. The inspector must issue the permit retroactively at no cost
  4. The homeowner is solely liable with no contractor consequence

Explanation

Beginning permitted work without a permit is a violation that can result in stop-work orders, penalties, and disciplinary action against the license. The work must still be permitted and inspected to demonstrate compliance.

Question 9General Plumbing Regulations, Definitions, and Administration

A plumbing business operates as a corporation. Under Alaska licensing rules, what is generally required for the corporation to offer plumbing services?

  1. Only the individual plumbers need licenses
  2. Any employee may serve as the qualifier
  3. The business must hold a contractor license with a qualifying plumber Correct answer.
  4. The corporation needs no license if it has insurance

Explanation

A business entity offering plumbing contracting services must hold the appropriate contractor license and have a qualified licensed plumber responsible for the work. Individual worker licenses alone do not authorize the entity to contract.

Question 10General Plumbing Regulations, Definitions, and Administration

When a code conflict arises between the adopted plumbing code and a local ordinance, what principle generally governs?

  1. The contractor chooses which to follow
  2. The older document controls
  3. The more restrictive provision generally controls Correct answer.
  4. The less restrictive provision always controls

Explanation

Where requirements conflict, the more stringent provision is generally applied to protect health and safety. This prevents a weaker local rule from lowering minimum safeguards.

Question 11General Plumbing Regulations, Definitions, and Administration

A plumber is asked to install a backflow prevention device on a commercial connection. Which principle best explains why this is required?

  1. To eliminate the need for venting
  2. To prevent contamination of the potable supply from cross-connections Correct answer.
  3. To reduce the number of fixtures allowed
  4. To increase water pressure at fixtures

Explanation

Backflow prevention protects the potable water supply from contamination caused by cross-connections and reverse flow. It is a public health safeguard, not a pressure or fixture-count control.

Question 12General Plumbing Regulations, Definitions, and Administration

What is the primary purpose of requiring licensure of plumbers in Alaska?

  1. To protect public health and safety through qualified work Correct answer.
  2. To guarantee lowest installation cost
  3. To limit competition among contractors
  4. To standardize fixture brand selection

Explanation

Licensing exists to protect public health and safety by ensuring plumbing work is performed by qualified individuals. It is not intended to limit competition or control product brands.

Question 13General Plumbing Regulations, Definitions, and Administration

A plumber discovers that a required inspection was missed because the general contractor covered the walls. What is the plumber's most appropriate action?

  1. Ignore it since the walls are closed
  2. Notify the authority and arrange to expose the work for inspection Correct answer.
  3. Sign off on the inspection personally
  4. Proceed and document it later

Explanation

Concealed work must still be inspected; the proper response is to notify the inspecting authority and expose the work so compliance can be verified. A plumber cannot self-approve inspections.

Question 14General Plumbing Regulations, Definitions, and Administration

Which term describes the minimum slope required for a horizontal drainage pipe to carry waste by gravity?

  1. Static lift
  2. Fixture load
  3. Fall or grade Correct answer.
  4. Head pressure

Explanation

Fall or grade refers to the downward slope of a horizontal drain that lets gravity move waste. Head pressure, static lift, and fixture load describe other hydraulic conditions.

Question 15General Plumbing Regulations, Definitions, and Administration

A contractor's license has lapsed while work is ongoing on a permitted project. What is the most accurate statement about continuing the work?

  1. The permit automatically transfers to the homeowner
  2. Work may continue because the permit was already issued
  3. Only the final inspection is affected
  4. Continuing to contract plumbing work without a valid license is a violation Correct answer.

Explanation

Holding a valid license is an ongoing requirement for contracting plumbing work; a lapsed license means continued contracting is a violation even if a permit exists. The permit does not cure the licensing lapse.

Question 16General Plumbing Regulations, Definitions, and Administration

In the definitions used by plumbing codes, what distinguishes a 'vent' from a 'drain'?

  1. Both serve identical functions
  2. A drain must be vertical and a vent horizontal
  3. A vent allows air into the system; a drain carries waste flow Correct answer.
  4. A vent carries waste; a drain carries air

Explanation

A vent provides air to balance pressure in the drainage system, while a drain conveys waste and water. They serve distinct but complementary functions.

Question 17General Plumbing Regulations, Definitions, and Administration

An owner-occupant performs plumbing work on their own single-family home but the local authority requires inspections. What is the owner's obligation?

  1. The owner may waive inspection in writing
  2. No inspection is needed for owner work
  3. The work must still be permitted and inspected Correct answer.
  4. Only electrical work needs inspection

Explanation

Owner-occupant allowances permit the owner to do the work but do not exempt the project from permitting and inspection. Compliance with the code must still be verified.

Question 18General Plumbing Regulations, Definitions, and Administration

A plumbing contractor is cited for a code violation on an installation. The contractor argues the plans, stamped by a designer, showed the noncompliant layout. How is this generally resolved?

  1. The designer alone bears all responsibility
  2. The contractor remains responsible for code compliance regardless of the plans Correct answer.
  3. The plans override the code automatically
  4. The inspector must approve whatever the plans show

Explanation

The adopted code sets minimum requirements that plans cannot override; the installing contractor remains responsible for compliant work. A designer's stamp does not authorize code violations.

Question 19General Plumbing Regulations, Definitions, and Administration

A journeyman plumber wants to start their own plumbing contracting business. What licensing step is generally required beyond holding a journeyman certificate?

  1. No additional step is needed
  2. Only register the business name
  3. Obtain the appropriate contractor/company license and serve as qualifier Correct answer.
  4. Purchase a surety bond in place of a license

Explanation

Operating a plumbing contracting business requires the appropriate contractor or company license with a qualified individual responsible for the work. A journeyman certificate alone does not authorize contracting.

Question 20General Plumbing Regulations, Definitions, and Administration

A local jurisdiction adopts a plumbing code edition that is stricter than the state minimum in one area. Which outcome is most consistent with code administration principles?

  1. The state code always preempts all local rules
  2. The stricter local requirement may apply if properly adopted Correct answer.
  3. The stricter local requirement is void because it exceeds the state code
  4. The contractor selects the edition to follow

Explanation

Local jurisdictions may adopt requirements that are at least as protective as the state minimum, and properly adopted stricter rules can apply. Contractors cannot choose which edition to follow.

Question 21Plumbing Math, Sizing Calculations, and Fixture Units

A single-bowl kitchen sink is rated at 2 fixture units. How many fixture units does a battery of three identical sinks contribute?

  1. 3 fixture units
  2. 6 fixture units Correct answer.
  3. 8 fixture units
  4. 2 fixture units

Explanation

Fixture units are additive when several fixtures of the same type are installed on a branch or building supply. Three sinks at 2 fixture units each total 3 × 2 = 6 fixture units.

Question 22Plumbing Math, Sizing Calculations, and Fixture Units

Water flows through a pipe at 12 gallons per minute. What is this flow rate expressed in gallons per hour?

  1. 180 gph
  2. 72 gph
  3. 720 gph Correct answer.
  4. 1,200 gph

Explanation

There are 60 minutes in an hour, so multiply the per-minute rate by 60. 12 gpm × 60 min/hr = 720 gph.

Question 23Plumbing Math, Sizing Calculations, and Fixture Units

Which term describes the vertical distance water must be lifted from a supply level to the highest fixture outlet?

  1. Static head Correct answer.
  2. Residual pressure
  3. Friction head
  4. Developed length

Explanation

Static head is the elevation-driven pressure created by the vertical height of water above a reference point. It depends only on height, not on flow or pipe length.

Question 24Plumbing Math, Sizing Calculations, and Fixture Units

A rectangular floor space measures 9 feet by 14 feet. What is its area in square feet?

  1. 252 sq ft
  2. 23 sq ft
  3. 126 sq ft Correct answer.
  4. 46 sq ft

Explanation

Area of a rectangle equals length times width. 9 ft × 14 ft = 126 sq ft.

Question 25Plumbing Math, Sizing Calculations, and Fixture Units

In a drainage system, which fixture unit value generally represents the discharge load of a water closet?

  1. 1 fixture unit
  2. 10 fixture units
  3. 6 fixture units Correct answer.
  4. 2 fixture units

Explanation

A water closet carries a relatively high drainage fixture-unit rating because of its large discharge volume. In common plumbing tables a tank-type water closet is rated at about 6 drainage fixture units.

Question 26Plumbing Math, Sizing Calculations, and Fixture Units

A cylindrical tank has a radius of 2 feet and a height of 5 feet. Using π ≈ 3.14, what is its approximate volume in cubic feet?

  1. 125.6 cu ft
  2. 31.4 cu ft
  3. 20.0 cu ft
  4. 62.8 cu ft Correct answer.

Explanation

Volume of a cylinder is π × r² × h. Here 3.14 × 2² × 5 = 3.14 × 4 × 5 = 62.8 cubic feet.

Question 27Plumbing Math, Sizing Calculations, and Fixture Units

A supply line delivers 15 gallons per minute. How many gallons does it deliver in 8 hours of continuous operation?

  1. 1,800 gallons
  2. 7,200 gallons Correct answer.
  3. 120 gallons
  4. 900 gallons

Explanation

Convert hours to minutes first: 8 hr × 60 min/hr = 480 minutes. Then 15 gpm × 480 min = 7,200 gallons.

Question 28Plumbing Math, Sizing Calculations, and Fixture Units

The pressure at the base of a column of water is 43.4 psi. Using 0.434 psi per foot of height, what is the approximate height of the column?

  1. 100 feet Correct answer.
  2. 50 feet
  3. 200 feet
  4. 18.8 feet

Explanation

Static pressure from elevation equals 0.434 psi per foot. Dividing 43.4 psi by 0.434 psi/ft gives 100 feet of height.

Question 29Plumbing Math, Sizing Calculations, and Fixture Units

A building has a total drainage load of 40 fixture units. If local code requires a 1-1/2 inch building drain for up to 30 fixture units and a 2 inch drain for up to 60 fixture units, what minimum drain size applies?

  1. 1-1/2 inch
  2. 3 inch
  3. 2 inch Correct answer.
  4. 4 inch

Explanation

The load of 40 fixture units exceeds the 30-unit limit for a 1-1/2 inch drain, so the next listed size must be used. A 2 inch drain covers up to 60 fixture units, which satisfies the 40-unit load.

Question 30Plumbing Math, Sizing Calculations, and Fixture Units

A pipe run consists of 24 feet of straight pipe. Each of four 90-degree elbows adds 2 feet of equivalent length. What is the total developed length?

  1. 26 feet
  2. 24 feet
  3. 32 feet Correct answer.
  4. 30 feet

Explanation

Developed length includes straight pipe plus the equivalent length of fittings. Four elbows × 2 ft = 8 ft of equivalent length, and 24 ft + 8 ft = 32 ft.

Question 31Plumbing Math, Sizing Calculations, and Fixture Units

A rectangular tank is 3 feet long, 2 feet wide, and 2 feet deep. How many cubic feet of water can it hold?

  1. 12 cu ft Correct answer.
  2. 6 cu ft
  3. 7 cu ft
  4. 24 cu ft

Explanation

Volume of a rectangular tank is length × width × depth. 3 ft × 2 ft × 2 ft = 12 cubic feet.

Question 32Plumbing Math, Sizing Calculations, and Fixture Units

A fixture group totals 18 water supply fixture units. If a pipe size is rated to carry 20 water supply fixture units, what can be concluded about that pipe size for this group?

  1. It must be increased two sizes
  2. It is undersized for the load
  3. It cannot be evaluated without flow pressure
  4. It is adequate for the load Correct answer.

Explanation

Water supply sizing compares the load in fixture units against the capacity of the pipe size. Since 18 units is below the 20-unit capacity, the pipe size is adequate.

Question 33Plumbing Math, Sizing Calculations, and Fixture Units

Water enters a system at 60 psi. Friction and elevation losses total 18 psi. What is the residual pressure at the outlet?

  1. 78 psi
  2. 18 psi
  3. 42 psi Correct answer.
  4. 3.3 psi

Explanation

Residual pressure equals the starting pressure minus all losses. 60 psi − 18 psi = 42 psi remaining at the outlet.

Question 34Plumbing Math, Sizing Calculations, and Fixture Units

A circular pipe has an inside diameter of 4 inches. Using the formula for area of a circle (A = πr²) with π ≈ 3.14, what is the approximate cross-sectional area in square inches?

  1. 12.56 sq in Correct answer.
  2. 6.28 sq in
  3. 50.24 sq in
  4. 25.12 sq in

Explanation

The radius is half the diameter, so r = 2 inches. Then A = 3.14 × 2² = 3.14 × 4 = 12.56 square inches.

Question 35Plumbing Math, Sizing Calculations, and Fixture Units

A plumbing system must deliver 30 gallons per minute through a pipe. If the design velocity limit is 8 feet per second, which statement best reflects the relationship being checked?

  1. Velocity equals flow rate times area
  2. Pressure equals velocity times area
  3. Flow rate equals velocity times cross-sectional area Correct answer.
  4. Flow rate equals velocity divided by area

Explanation

The continuity relationship states that volumetric flow equals velocity multiplied by the pipe's cross-sectional area. Sizing to a velocity limit means choosing an area large enough that Q/A stays at or below the limit.

Question 36Plumbing Math, Sizing Calculations, and Fixture Units

A building's total supply load is 45 water supply fixture units. A meter and service are being selected, and the available pressure is limited. Which factor most directly affects the minimum pipe size chosen for the service?

  1. The water heater brand
  2. The number of floors in the building only
  3. The color of the pipe
  4. The allowable pressure loss over the developed length Correct answer.

Explanation

Service sizing balances the fixture-unit load against the pressure that can be sacrificed to friction over the developed length. A larger allowable loss permits a smaller pipe for the same load.

Question 37Plumbing Math, Sizing Calculations, and Fixture Units

A horizontal run rises 6 feet over a developed length of 60 feet. What is the approximate slope expressed as a percentage?

  1. 6 percent
  2. 1 percent
  3. 10 percent Correct answer.
  4. 0.1 percent

Explanation

Percent slope equals rise divided by run, times 100. 6 ft ÷ 60 ft = 0.10, and 0.10 × 100 = 10 percent.

Question 38Plumbing Math, Sizing Calculations, and Fixture Units

Two branch loads of 12 and 18 water supply fixture units combine into one main. If the main is sized for the sum of the loads, what is the combined load in fixture units?

  1. 30 fixture units Correct answer.
  2. 15 fixture units
  3. 216 fixture units
  4. 6 fixture units

Explanation

Loads on a common main are added together to determine the total demand in fixture units. 12 + 18 = 30 fixture units.

Question 39Plumbing Math, Sizing Calculations, and Fixture Units

A pipe with a 6-inch inside diameter carries water. Using A = πr² with π ≈ 3.14, what is the approximate cross-sectional area in square inches?

  1. 9.42 sq in
  2. 113.04 sq in
  3. 28.26 sq in Correct answer.
  4. 18.84 sq in

Explanation

Radius is half of 6 inches, so r = 3 inches. Then A = 3.14 × 3² = 3.14 × 9 = 28.26 square inches.

Question 40Plumbing Math, Sizing Calculations, and Fixture Units

A horizontal drain line must fall 1/4 inch per foot of run. Over a run of 16 feet, what is the total fall in inches?

  1. 16 inches
  2. 4 inches Correct answer.
  3. 8 inches
  4. 2 inches

Explanation

Total fall equals the per-foot slope multiplied by the run length: 0.25 in/ft × 16 ft = 4 inches. Multiplying the slope by the full run length is the standard method for computing drain fall.

Question 41Drainage Systems, Traps, and Vents

What is the minimum liquid capacity of a water closet trapway requirement under standard plumbing practice?

  1. The trapway must be at least 3 inches in diameter throughout
  2. The trapway must be a minimum of 2 inches in diameter throughout Correct answer.
  3. The trapway must be at least 1.5 inches in diameter throughout
  4. The trapway must be at least 4 inches in diameter throughout

Explanation

Water closets are required to have a trapway with a minimum uniform diameter of 2 inches to pass waste without clogging. Smaller diameters restrict solids, and larger diameters are not used because the bowl outlet and fixture design govern the size.

Question 42Drainage Systems, Traps, and Vents

The vertical distance between a fixture's trap weir and the connection to the building drain is measured to determine what?

  1. The fixture's trap seal
  2. The trap arm slope
  3. The vent stack diameter
  4. The fall available for drainage Correct answer.

Explanation

Drainage relies on gravity, so the vertical distance from the trap weir down to the building drain determines the available fall. This fall must be enough to carry waste while maintaining slope, and it feeds into the rules about whether a fixture can drain to a given point.

Question 43Drainage Systems, Traps, and Vents

A plumbing vent that rises through a roof must extend how far above the roof surface when the roof is a flat roof used only for weather protection?

  1. At least 24 inches above the roof surface
  2. At least 3 inches above the roof surface
  3. At least 12 inches above the roof surface
  4. At least 6 inches above the roof surface Correct answer.

Explanation

Vent terminals on flat roofs generally must extend a minimum of 6 inches above the roof surface to keep snow and debris from blocking the opening. Greater heights are required only where the roof is used for purposes other than weather protection.

Question 44Drainage Systems, Traps, and Vents

What is the primary purpose of a vent in a drainage system?

  1. To provide a cleanout access point
  2. To equalize air pressure and protect trap seals Correct answer.
  3. To increase the velocity of wastewater flow
  4. To filter sewer gases before release

Explanation

Vents admit air behind the flowing waste so the system stays at atmospheric pressure, which prevents siphonage of trap seals. They do not treat or filter gas; they simply balance pressure and allow gases to escape above the roof.

Question 45Drainage Systems, Traps, and Vents

A trap seal is measured as the vertical distance between which two points?

  1. The crown of the trap and the roof terminal
  2. The trap weir and the bottom of the trap dip Correct answer.
  3. The trap inlet and the vent connection
  4. The fixture outlet and the building drain

Explanation

The trap seal is the depth of water held between the trap weir (the overflow level) and the lowest point of the trap dip. This water column is what blocks sewer gas from entering the fixture.

Question 46Drainage Systems, Traps, and Vents

A sink trap has a seal depth of 1 inch. What is the problem with this installation?

  1. The seal is adequate for a kitchen sink
  2. The seal is too deep and will cause gurgling
  3. The seal is too deep and will slow drainage
  4. The seal is too shallow and can be lost by evaporation or siphonage Correct answer.

Explanation

Traps are required to maintain a seal of at least 2 inches and no more than 4 inches. A 1-inch seal is below the minimum and can be broken easily by evaporation, back pressure, or minor siphonage, allowing sewer gas into the building.

Question 47Drainage Systems, Traps, and Vents

Which type of trap is prohibited in plumbing drainage systems because it can lose its seal easily?

  1. S-trap Correct answer.
  2. Drum trap
  3. Bell trap
  4. P-trap

Explanation

S-traps are prohibited because their shape causes a double siphon that empties the seal each time the fixture drains. P-traps with a proper vent are the approved configuration.

Question 48Drainage Systems, Traps, and Vents

What is the maximum developed length of a trap arm for a 2-inch trap before a vent is required, assuming a slope of 1/4 inch per foot?

  1. 15 feet
  2. 10 feet
  3. 8 feet Correct answer.
  4. 5 feet

Explanation

The trap arm length is limited so the slope does not drop the arm below the vent connection and cause the trap to siphon. For a 2-inch trap at 1/4 inch per foot, the maximum developed length is 8 feet, matching the pipe diameter in inches times the allowable fall.

Question 49Drainage Systems, Traps, and Vents

A vent stack serving a building must extend how far above the highest fixture it serves before turning horizontally?

  1. At least 3 inches above the flood level rim of the highest fixture
  2. At least 12 inches above the flood level rim of the highest fixture
  3. At least 6 inches above the flood level rim of the highest fixture Correct answer.
  4. At least 24 inches above the flood level rim of the highest fixture

Explanation

A vent must rise at least 6 inches above the flood level rim of the highest fixture before any horizontal offset. This keeps the vent clear of water that could back up in the fixture and prevents the vent from becoming a drain.

Question 50Drainage Systems, Traps, and Vents

What is the minimum size of a building drain serving a single-family dwelling?

  1. 2 inches
  2. 1.5 inches
  3. 4 inches
  4. 3 inches Correct answer.

Explanation

A building drain for a dwelling must be at least 3 inches in diameter to carry the fixture unit load and to accommodate the required slope. Smaller sizes cannot handle the combined discharge reliably.