Journeyman Plumber Exam — Questions and Answers

Question 1: A sediment trap (drip leg) in a gas piping system must be installed:

At the gas meter outlet
Only on systems using propane
At the highest point in the system
Immediately upstream of each appliance (Correct answer)

Correct answer: Immediately upstream of each appliance

Sediment traps must be installed immediately upstream of each appliance connection to collect moisture and debris before they enter the appliance's gas valve.

Question 2: A plumber is installing the drain for a kitchen sink, which has a 1-1/2 inch P-trap. What is the maximum horizontal distance the trap arm can be from the vent fitting?

8 feet
3 feet 6 inches (Correct answer)
6 feet
5 feet

Correct answer: 3 feet 6 inches

The maximum horizontal distance between a fixture trap and its vent is determined by the size of the trap arm. For a 1-1/2 inch pipe, this distance is typically limited to 3 feet 6 inches to ensure proper venting and prevent the trap from being siphoned.

Question 3: Which condition is considered a cross-connection in a DWV system?

A common vent serving two lavatories
A drain pipe connected directly to a potable water supply pipe (Correct answer)
A soil stack receiving waste from multiple floors
Two vent pipes tied together above the fixtures

Correct answer: A drain pipe connected directly to a potable water supply pipe

A cross-connection occurs when a drain pipe is directly connected to a potable water supply, creating a potential for contamination.

Question 4: Which of the following is the correct way to check for a gas leak at a connection?

Listen carefully for a hissing sound only
Use an open flame to detect combustible gas
Apply listed leak detection solution and observe for bubbles (Correct answer)
Use your sense of smell exclusively

Correct answer: Apply listed leak detection solution and observe for bubbles

Listed leak detection solution (or an electronic gas detector) is the approved method; open flames are dangerous and smell alone may miss small leaks.

Question 5: A sanitary tee may be used in a drainage system in which orientation?

Horizontally with the branch pointing up
As a horizontal-to-horizontal fitting only
On its back in a horizontal run
In a vertical stack receiving horizontal branch connections (Correct answer)

Correct answer: In a vertical stack receiving horizontal branch connections

Sanitary tees are approved for use in the vertical position where a horizontal branch connects to a vertical stack.

Question 6: On an isometric drawing, which axis represents pipes running left-to-right (east-west) in the field?

The right-leaning 30-degree axis (Correct answer)
The 45-degree axis
The left-leaning 30-degree axis
The vertical axis

Correct answer: The right-leaning 30-degree axis

By convention, the right-leaning 30-degree axis on an isometric drawing represents east-west (left-to-right) pipe runs.

Question 7: Where must a temperature and pressure (T&P) relief valve discharge pipe terminate?

Into the cold water supply line
At least 24 inches above the floor
Within 6 inches of the floor (Correct answer)
Directly into a floor drain

Correct answer: Within 6 inches of the floor

T&P relief valve discharge pipes must terminate within 6 inches of the floor to direct scalding water safely downward away from occupants.

Question 8: Which document primarily governs plumbing installations in most US jurisdictions?

OSHA 29 CFR 1910
ANSI A112.18
NFPA 13
International Plumbing Code (IPC) or Uniform Plumbing Code (UPC) (Correct answer)

Correct answer: International Plumbing Code (IPC) or Uniform Plumbing Code (UPC)

Most US jurisdictions adopt either the IPC or UPC as their primary plumbing code.

Question 9: Under the IPC, the maximum water pressure at any fixture in a building shall not exceed:

100 psi
80 psi (Correct answer)
60 psi
120 psi

Correct answer: 80 psi

The IPC sets 80 psi as the maximum allowable water pressure at any fixture; a pressure reducing valve must be installed if supply exceeds this.

Question 10: When installing Corrugated Stainless Steel Tubing (CSST) for a gas line in a residence, what is the minimum size copper bonding conductor required to be connected from the gas piping system to the building's electrical service grounding electrode system?

12 AWG
10 AWG
6 AWG (Correct answer)
8 AWG

Correct answer: 6 AWG

According to the International Fuel Gas Code (IFGC) and CSST manufacturer instructions, the bonding conductor for a CSST gas piping system must be no smaller than a 6 AWG copper wire or its equivalent. This bonding is crucial to protect the thin-walled tubing from damage due to electrical events like lightning strikes or power surges, which could otherwise create a fire or explosion hazard.

Question 11: Which of the following scenarios describes an unprotected cross-connection that could lead to a dangerous backflow event?

A commercial boiler connected to the potable water supply via an RPZ assembly.
A faucet spout terminating 2 inches above the flood level rim of a lavatory.
A garden hose with its end submerged in a bucket of pesticide solution. (Correct answer)
A toilet fill valve with an integral anti-siphon device installed above the critical level.

Correct answer: A garden hose with its end submerged in a bucket of pesticide solution.

A cross-connection is any actual or potential link between a potable water system and a source of contamination. Submerging a hose connected to the potable supply into a non-potable solution like pesticides creates a direct cross-connection. If a back-siphonage event occurs, the pesticide will be drawn into the water supply. The other options describe properly protected connections.

Question 12: A plumber must make a parallel offset of 6 inches using 45-degree fittings. What length of pipe is needed between the two elbows (the travel)?

8.49 inches (Correct answer)
6.00 inches
12.00 inches
4.24 inches

Correct answer: 8.49 inches

Travel = set × 1.414, so 6 × 1.414 = 8.49 inches.

Question 13: A plumber is using the longest length method to size a natural gas piping system. What is the first critical measurement required for this method?

The measured length of pipe from the point of delivery to the most remote gas outlet. (Correct answer)
The diameter of the gas meter outlet.
The total connected BTUH load of all appliances.
The gas pressure at the street main.

Correct answer: The measured length of pipe from the point of delivery to the most remote gas outlet.

According to the longest length method described in fuel gas codes, the initial step is to determine the measured distance from the gas meter (point of delivery) to the appliance furthest away in the piping system. This total length is then used in conjunction with the total appliance load to find the correct pipe size from the code's sizing tables.

Question 14: Which of the following backflow prevention devices is considered the most effective and simplest form, providing a physical separation between the potable water outlet and a potential contaminant?

Double Check Valve Assembly (DCVA)
Reduced Pressure Zone Assembly (RPZ)
Pressure Vacuum Breaker (PVB)
Air Gap (Correct answer)

Correct answer: Air Gap

An air gap is a physical separation between the free-flowing discharge end of a potable water supply pipe and the flood-level rim of a receptacle. It is the most reliable and simplest method of backflow prevention because there is no physical connection for contaminants to cross.

Question 15: What organization publishes the Uniform Plumbing Code (UPC) that governs backflow prevention requirements in many US jurisdictions?

American Society of Sanitary Engineering (ASSE)
International Association of Plumbing and Mechanical Officials (IAPMO) (Correct answer)
American Water Works Association (AWWA)
National Fire Protection Association (NFPA)

Correct answer: International Association of Plumbing and Mechanical Officials (IAPMO)

The Uniform Plumbing Code (UPC) is published by IAPMO and is adopted by many western US states as the governing plumbing standard.

Question 16: On an isometric drawing, how is pipe size typically noted?

By a numerical callout adjacent to the pipe line (Correct answer)
By the length of the line drawn
By line thickness alone
By color coding

Correct answer: By a numerical callout adjacent to the pipe line

Pipe size is indicated by a numerical callout (e.g., 2", 3") written next to the pipe line on isometric drawings.

Question 17: In an isometric plumbing drawing, a pipe is shown as a vertical line. It then turns and runs horizontally away from the viewer and to the right. Which of the following best describes how the horizontal pipe would be drawn?

As a line angled at 30 degrees up from the horizontal. (Correct answer)
As a horizontal line running straight to the right.
As a line angled at 45 degrees up from the horizontal.
As a vertical line running down.

Correct answer: As a line angled at 30 degrees up from the horizontal.

In standard isometric drawings, vertical lines are drawn vertically, while horizontal lines (representing length and width) are drawn at 30 degrees to the horizontal plane to create a three-dimensional view on a two-dimensional surface.

Question 18: What type of backflow is caused by a negative or sub-atmospheric pressure in the water supply piping, often resulting from a water main break or firefighting activities nearby?

Hydraulic shock
Back-siphonage (Correct answer)
Back-pressure
Cross-contamination

Correct answer: Back-siphonage

Back-siphonage is the reversal of flow caused by a reduction in system pressure, which creates a partial vacuum that can pull contaminants into the potable water supply. This is different from back-pressure, which occurs when downstream pressure is higher than the supply pressure.

Question 19: A horizontal drainage pipe that is 48 feet long must be installed with a uniform grade of 1/4 inch per foot. What is the total fall of the pipe from its highest point to its lowest point?

6 inches
8 inches
24 inches
12 inches (Correct answer)

Correct answer: 12 inches

The total fall is calculated by multiplying the length of the pipe in feet by the required grade in inches per foot. Calculation: 48 feet * (1/4 inch/foot) = 12 inches.

Question 20: A gas piping system operating at pressures above ½ psig but not exceeding 2 psig is classified as:

High pressure
Intermediate pressure
Low pressure
Medium pressure (Correct answer)

Correct answer: Medium pressure

NFPA 54 classifies gas piping at pressures above ½ psig (14 inches WC) up to 2 psig as a medium-pressure system, requiring different materials and joining methods.

Question 21: A kitchen cannot be on the accessible route for individuals using public plumbing facilities.

FALSE
TRUE (Correct answer)

Correct answer: TRUE

Accessible pathways to public restrooms are not permitted to go through kitchens, closets, storage rooms, or other similar areas.

Question 22: A plumber needs to install a 45-degree offset. The horizontal distance between the centerlines of the two parallel pipes, known as the 'set', is 20 inches. What is the center-to-center length of the 'travel' piece of pipe?

20 inches
34 5/8 inches
28 1/4 inches (Correct answer)
24 1/2 inches

Correct answer: 28 1/4 inches

To find the travel for a 45-degree offset, you multiply the 'set' by the constant 1.414. In this case, 20 inches (set) x 1.414 = 28.28 inches. The closest fractional answer is 28 1/4 inches (28.25).

Question 23: A newly installed potable water supply system within a commercial building must be tested for integrity. According to most plumbing codes, what is the minimum required hydrostatic test pressure?

100 psi for 15 minutes
1.5 times the working pressure, but not less than 150 psi, for 2 hours (Correct answer)
The system's working pressure for 2 hours
50 psi for 4 hours

Correct answer: 1.5 times the working pressure, but not less than 150 psi, for 2 hours

Most plumbing codes, including the International Plumbing Code (IPC) and Uniform Plumbing Code (UPC), require that new potable water piping be tested at a pressure of at least 1.5 times the working pressure under which it is to be used. If the working pressure is unknown, a common standard is a minimum of 150 psi. The duration for this test is typically a minimum of 2 hours with no allowable leakage.

Question 24: When a lavatory is installed in a wheelchair-accessible restroom, the drain trap and supply pipes must be:

Insulated to protect users from contact burns (Correct answer)
Raised to the standard 21-inch rough-in height
Concealed inside the wall with access panels
Installed with chrome-plated exposed pipes only

Correct answer: Insulated to protect users from contact burns

ADA-compliant accessible lavatories require insulated or covered drain and supply pipes to prevent burns to users with limited sensation who may contact the pipes.

Question 25: A pilot light that repeatedly goes out on a gas appliance most likely indicates a problem with:

The vent cap
The main gas valve
The pressure regulator
The thermocouple or thermopile (Correct answer)

Correct answer: The thermocouple or thermopile

The thermocouple generates a small voltage when heated by the pilot flame; if it fails or is positioned incorrectly, it causes the safety valve to close, extinguishing the pilot.

Question 26: Which of the following best describes back-pressure (positive pressure) in a drainage stack?

Water pressure from the supply system entering the drain
Negative pressure caused by a fast-moving slug of water in the stack
Pressure that builds below a slug of falling water and can push trap seals into the room (Correct answer)
Pressure loss from undersized vent pipes

Correct answer: Pressure that builds below a slug of falling water and can push trap seals into the room

As a slug of water falls down a tall stack, it compresses air below it, creating positive pressure that can force trap seals out of lower-floor fixture traps.

Question 27: A plumber is installing a horizontal 3-inch PVC drain line that will carry waste from a bathroom group. According to most plumbing codes, what is the MINIMUM required slope for this pipe?

1/4 inch per foot
1/2 inch per foot
1/16 inch per foot
1/8 inch per foot (Correct answer)

Correct answer: 1/8 inch per foot

For horizontal drainage pipes between 3 and 6 inches in diameter, the standard minimum slope required by the International Plumbing Code (IPC) is 1/8 inch per foot. This ensures that solids are carried along with the liquids without the risk of stranding.

Question 28: When installing a wall-hung toilet, the carrier must be secured to:

The finished wall framing only
The structural floor and wall framing (Correct answer)
The subfloor with lag bolts only
The drain pipe and vent stack

Correct answer: The structural floor and wall framing

Wall-hung toilet carriers must be anchored to both the structural floor and wall framing to support the full weight and dynamic loads of use.

Question 29: A journeyman plumber is installing fixtures in an ADA-compliant public restroom. What is the required height range for the toilet seat above the finished floor?

14 to 16 inches
23 to 25 inches
17 to 19 inches (Correct answer)
20 to 22 inches

Correct answer: 17 to 19 inches

The Americans with Disabilities Act (ADA) standards require that the top of the toilet seat in an accessible restroom be between 17 and 19 inches above the finished floor. This height makes it easier for individuals with mobility impairments, particularly those transferring from a wheelchair, to use the fixture.

Question 30: It is necessary to pipe clear water waste from a potable source through an air gap, such as a relief valve on a water heater, to an indirect waste.

FALSE
TRUE (Correct answer)

Correct answer: TRUE

It is required to pipe clear water waste from a potable water system to an indirect waste and discharge it through an air gap. This is as easy as terminating the discharge pipe of a floor drain six inches above the strainer.

Question 31: Which type of valve is required to be installed on the water supply to a water heater to allow for servicing?

Pressure reducing valve
Check valve
Backflow preventer
Gate valve or full-port ball valve (Correct answer)

Correct answer: Gate valve or full-port ball valve

A gate valve or full-port ball valve must be installed on the cold water supply to a water heater to allow isolation for service.

Question 32: A wet vent is permitted to serve which type of fixture combination?

Two water closets on separate floors
Bathtub and lavatory on the same floor level (Correct answer)
Water closet and kitchen sink only
Floor drain and clothes washer only

Correct answer: Bathtub and lavatory on the same floor level

A wet vent typically serves a lavatory and bathtub/shower combination where the drain pipe also functions as the vent for the upstream fixture.

Question 33: How far above the flood level rim of a fixture must a vent pipe rise before offsetting horizontally?

4 inches
1 foot
2 inches
6 inches (Correct answer)

Correct answer: 6 inches

A vent pipe must rise at least 6 inches above the flood level rim of the highest served fixture before making a horizontal offset.

Question 34: What is the maximum allowable pressure drop for a low-pressure residential gas distribution system serving appliances?

2.0 inch W.C.
0.5 inch W.C. (Correct answer)
1.0 inch W.C.
0.2 inch W.C.

Correct answer: 0.5 inch W.C.

Low-pressure residential systems must not lose more than 0.5 inch W.C. between the meter outlet and any appliance connection.

Question 35: When creating an offset using two 60-degree fittings, the distance between the centerlines of the parallel pipes is 15 inches. What is the approximate length of the travel pipe required between the fittings?

21.2 inches
15.0 inches
17.3 inches (Correct answer)
30.0 inches

Correct answer: 17.3 inches

The constant for a 60-degree offset is 1.155. The travel is calculated by multiplying the offset (15 inches) by 1.155, which equals 17.325 inches.

Question 36: Which type of faucet uses a ceramic disc cartridge to control water flow?

Cartridge faucet
Compression faucet
Ball faucet
Disc faucet (Correct answer)

Correct answer: Disc faucet

Disc faucets use a ceramic disc cylinder that rotates to open and close ports, controlling both flow and temperature.

Question 37: What is the correct rough-in distance for a standard toilet measured from the finished wall to the center of the drain?

12 inches (Correct answer)
10 inches
14 inches
16 inches

Correct answer: 12 inches

The standard toilet rough-in distance is 12 inches from the finished wall to the centerline of the closet flange, though 10-inch and 14-inch models exist.

Question 38: When a gas appliance is located in a confined space that is not connected to outside air, combustion air can be supplied by:

A single large opening sized at 1 square inch per 1,000 BTU/hr
Two permanent openings: one within 12 inches of the top and one within 12 inches of the floor (Correct answer)
A mechanical exhaust fan running continuously
Opening a nearby window during appliance operation

Correct answer: Two permanent openings: one within 12 inches of the top and one within 12 inches of the floor

NFPA 54 requires two permanent openings in a confined space — one high and one low — to allow natural convective circulation of combustion and dilution air.

Question 39: An isometric drawing shows an air admittance valve (AAV) terminating the vent on a kitchen sink island. What is the minimum height above the drain inlet an AAV must be installed?

6 inches
12 inches
2 inches
4 inches (Correct answer)

Correct answer: 4 inches

An AAV must be installed a minimum of 4 inches above the drain inlet it serves to function properly and prevent submersion.

Question 40: What is the primary purpose of a vent in a drain, waste, and vent (DWV) system?

To allow for the emergency drainage of stormwater.
To regulate air pressure within the drainage system and prevent the siphoning of trap seals. (Correct answer)
To provide a point of access for cleaning the drain lines.
To filter out solid waste materials before they enter the main sewer line.

Correct answer: To regulate air pressure within the drainage system and prevent the siphoning of trap seals.

The primary purpose of a vent system is to regulate air pressure within the plumbing system. This allows drains to flow freely and prevents the vacuum effect that can siphon water out of fixture traps, which would otherwise allow sewer gases to enter the building.

Question 41: What is the primary purpose of an isometric drawing in plumbing?

To calculate pipe pressures
To show a 3D representation of a piping system on a 2D surface (Correct answer)
To determine pipe sizing
To show a top-down floor plan

Correct answer: To show a 3D representation of a piping system on a 2D surface

Isometric drawings allow plumbers to visualize and communicate 3D pipe routing using a standardized 2D projection.

Question 42: An air gap is the physical separation between a water supply outlet and the flood level rim of a receiving vessel. What is the minimum air gap for a 1-inch supply pipe?

1 inch
2 inches (Correct answer)
1.5 inches
3 inches

Correct answer: 2 inches

The minimum air gap is twice the effective opening of the supply pipe, so a 1-inch pipe requires at least a 2-inch air gap.

Question 43: When installing a water service line, what is the general code requirement for the minimum horizontal separation distance between the potable water line and a sanitary sewer line in the same trench?

The pipes must be separated by at least 5 feet of undisturbed earth.
A minimum of 18 inches is required, regardless of pipe material.
There is no minimum separation if the sewer pipe is cast iron.
The water line must be placed on a shelf 12 inches above the sewer line. (Correct answer)

Correct answer: The water line must be placed on a shelf 12 inches above the sewer line.

To prevent contamination of the potable water supply in case of a leak, plumbing codes mandate specific separation requirements. The most common rule is that if the water line and sewer line are in the same trench, the water line must be placed on a solid shelf of earth at least 12 inches above the top of the sewer line. If they are at the same elevation, a much greater horizontal separation is required.

Question 44: To properly size a water supply system, a plumber uses the Water Supply Fixture Unit (WSFU) method. Which of the following best describes the principle behind this method?

It measures the static pressure required to operate the most demanding fixture in the system.
It calculates the peak water demand assuming all fixtures are used simultaneously.
It assigns a weight to each fixture based on its water consumption, duration of use, and frequency of use to determine the probable peak demand. (Correct answer)
It determines the pipe size based solely on the total number of fixtures in the building, regardless of type.

Correct answer: It assigns a weight to each fixture based on its water consumption, duration of use, and frequency of use to determine the probable peak demand.

The Water Supply Fixture Unit (WSFU) method, developed by Roy B. Hunter, is based on the theory of probability. It recognizes that not all fixtures will be used at the same time. Each fixture is assigned a WSFU value that represents its load-producing characteristics (water consumption, duration, and frequency of use), and these values are summed to estimate the peak probable demand on the system.

Question 45: An atmospheric gas water heater is installed in a confined mechanical room. What is required to ensure safe operation?

A dedicated combustion air supply to the confined space (Correct answer)
An exhaust fan rated for continuous duty
No additional provisions if the room has a door
A carbon monoxide detector only

Correct answer: A dedicated combustion air supply to the confined space

Atmospheric gas water heaters require adequate combustion air; when installed in a confined space, openings or ducts providing a dedicated combustion air supply from outside or an adjacent unconfined space are required.

Question 46: What is the maximum allowable pressure drop for a gas piping system serving appliances on a low-pressure system (under 2 psi)?

0.5 inches water column (Correct answer)
1.0 inches water column
0.3 inches water column
2.0 inches water column

Correct answer: 0.5 inches water column

Low-pressure gas systems (under 2 psi) are typically designed for a maximum allowable pressure drop of 0.5 inches water column from the meter to the appliance.

Question 47: A plumber needs to cut a piece of copper pipe to connect two 90-degree wrought copper elbows. The center-to-center measurement between where the fittings will be is 36 inches. The fitting allowance (take-off) for each elbow is 3/4 inch. What is the required end-to-end cut length of the pipe?

36 inches
34 1/2 inches (Correct answer)
35 1/4 inches
37 1/2 inches

Correct answer: 34 1/2 inches

To find the cut length of the pipe, the take-off for both fittings must be subtracted from the center-to-center measurement. The pipe fits into the sockets of the fittings. Calculation: 36" - (3/4" + 3/4") = 36" - 1 1/2" = 34 1/2 inches.

Question 48: When installing a drum trap, where must the outlet be located relative to the inlet?

Below the inlet
At the top of the trap body
At least 2 inches above the inlet (Correct answer)
At the same level as the inlet

Correct answer: At least 2 inches above the inlet

The outlet of a drum trap must be located at least 2 inches above the inlet to maintain the water seal.

Question 49: Which type of backflow is caused by downstream pressure exceeding supply pressure?

Vapor lock backflow
Thermal expansion backflow
Back-siphonage
Back-pressure backflow (Correct answer)

Correct answer: Back-pressure backflow

Back-pressure backflow occurs when downstream pressure (from pumps, boilers, or elevated tanks) exceeds the supply pressure.

Question 50: Which of the following joints is NOT acceptable for use in gas piping systems?

Flared joints on copper tubing
Threaded joints with approved sealant
Solvent-cemented plastic pipe joints (Correct answer)
Welded joints

Correct answer: Solvent-cemented plastic pipe joints

Solvent-cemented joints on plastic pipe are not acceptable for gas distribution inside buildings, as they are not rated for gas service in above-ground applications.

Question 51: A double check valve assembly (DCVA) is appropriate for which hazard classification?

Low-hazard (non-health) connections only (Correct answer)
Severe toxic hazard connections
Any hazard level when installed with an air gap
High-hazard connections only

Correct answer: Low-hazard (non-health) connections only

DCVAs are rated for low-hazard (non-health) cross-connections where contamination would be a nuisance but not a health risk, such as lawn irrigation without chemical injection.

Question 52: An atmospheric vacuum breaker (AVB) is installed on a utility sink faucet to prevent back-siphonage. Which of the following is a critical installation requirement for this device to function correctly?

It must be installed at least 6 inches above the flood-level rim of the fixture. (Correct answer)
It can be subjected to continuous pressure for up to 24 hours.
It is effective against both back-siphonage and backpressure.
It must be installed with a shutoff valve downstream of the device.

Correct answer: It must be installed at least 6 inches above the flood-level rim of the fixture.

An Atmospheric Vacuum Breaker (AVB) works by allowing air to enter and break a siphon. For it to function properly, it must be installed at least 6 inches above the flood-level rim of the fixture or the highest outlet it serves. It cannot be under continuous pressure and cannot have any shutoff valves downstream, as this would prevent it from opening to the atmosphere.

Question 53: Under the IPC, what is the maximum distance a trap can be located from its vent?

The distance depends on the pipe size and slope (Correct answer)
10 feet for all pipe sizes
2 feet
6 feet

Correct answer: The distance depends on the pipe size and slope

The maximum trap-to-vent distance is determined by the pipe diameter — for example, 3.5 feet for a 1.25-inch pipe and 6 feet for a 2-inch pipe.

Question 54: In an isometric drawing, a P-trap is shown with its outlet connecting to a horizontal drain pipe. What is the maximum distance the trap outlet can be from the vent under most US codes?

8 feet
10 feet
12 feet
6 feet (Correct answer)

Correct answer: 6 feet

Under most US plumbing codes, the trap-to-vent distance (trap arm length) for a P-trap must not exceed the distances in the code table, typically 6 feet for a 1.5" trap.

Question 55: Which appliance requires a dedicated GFCI-protected circuit AND a plumbing drain connection?

Clothes washer (Correct answer)
Garbage disposal
Gas range
Dishwasher

Correct answer: Clothes washer

A clothes washer requires both a dedicated electrical circuit (with GFCI in some locations) and a standpipe drain connection for proper installation.

Question 56: Combustion air for a gas-fired water heater in a confined space can be provided by:

One opening at the top of the space only
Two permanent openings — one near the top and one near the bottom of the enclosure (Correct answer)
No openings are needed if the burner is sealed
A single large opening on any wall

Correct answer: Two permanent openings — one near the top and one near the bottom of the enclosure

A confined space requires two openings — one within 12 inches of the ceiling and one within 12 inches of the floor — to allow adequate air circulation.

Question 57: During a backflow assembly test, the first check valve of an RPZ fails to hold. The correct action is to:

Report the failed test and have the assembly repaired or replaced before returning to service (Correct answer)
Tighten the packing nut on the check valve stem to restore seating
Leave the assembly in place since the second check valve provides backup protection
Install a supplemental check valve on the upstream piping and retest

Correct answer: Report the failed test and have the assembly repaired or replaced before returning to service

A failed backflow preventer test requires the assembly to be repaired or replaced by a qualified technician before it is returned to service.

Question 58: What is the purpose of a sanitary cross fitting, and where is its use restricted?

It is a venting fitting allowed only above the flood level rim
It is used in drainage systems only in horizontal-to-horizontal connections where permitted (Correct answer)
It connects two supply lines and is restricted to hot water systems
It joins four drain lines and is unrestricted in use

Correct answer: It is used in drainage systems only in horizontal-to-horizontal connections where permitted

Sanitary crosses are generally restricted to horizontal drain installations and must not be used in vertical stacks because they can cause cross-flow.

Question 59: A plumber is installing a 4-inch horizontal building drain that makes a single 90-degree turn. Which of the following statements about cleanout requirements is correct according to most plumbing codes?

A cleanout is not required if a fixture with a removable trap is located within 5 feet of the turn.
A cleanout is required at each change of direction greater than 45 degrees. (Correct answer)
A cleanout is only required if the total length of the drain exceeds 100 feet.
A cleanout can be omitted if two 45-degree fittings are used to make the turn.

Correct answer: A cleanout is required at each change of direction greater than 45 degrees.

Plumbing codes, such as the IPC Section 708.1.4, mandate the installation of cleanouts to allow access for clearing blockages. For horizontal drainage pipes, a cleanout is explicitly required at each change of direction that is greater than 45 degrees.

Question 60: On an isometric drawing, a pipe running parallel to the right front edge of the cube is drawn at what angle from horizontal?

30 degrees (Correct answer)
90 degrees
60 degrees
45 degrees

Correct answer: 30 degrees

In isometric drawing, the three primary axes are drawn at 30 degrees above horizontal (left and right) and vertical.

Question 61: What is the purpose of the bypass valve on a backflow preventer assembly installed in a commercial building?

To reduce system pressure to an acceptable level
To provide an alternate path for backflow to discharge safely
To allow water to flow while the assembly is being tested or repaired (Correct answer)
To equalize pressure on both sides of the check valves

Correct answer: To allow water to flow while the assembly is being tested or repaired

A bypass with a backflow preventer allows the building to maintain water service while the primary assembly is taken offline for testing or maintenance.

Question 62: Which of the following places wouldn't be a good place for an indirect waste receptor?

Unvented areas
Both Closets and Unvented areas (Correct answer)
Closets
None of the above

Correct answer: Both Closets and Unvented areas

Closets and unvented spaces are not appropriate places to install indirect waste receptors. It is necessary for all indirect waste receptors to be reachable.

Question 63: What is the primary purpose of a pressure regulator on a gas system?

To shut off gas flow during a leak
To measure gas consumption for billing
To increase gas pressure to appliances
To reduce and stabilize supply pressure to a safe, usable level (Correct answer)

Correct answer: To reduce and stabilize supply pressure to a safe, usable level

A pressure regulator reduces the higher distribution pressure to the lower, stable pressure required by appliances and maintains that pressure under varying flow conditions.

Question 64: What is the constant used to calculate the travel of a 60-degree offset?

1.155 (Correct answer)
1.414
0.866
0.707

Correct answer: 1.155

The travel constant for a 60-degree offset is 1.155, meaning travel = set × 1.155.

Question 65: On an isometric plumbing drawing, a double sanitary tee (back-to-back) is shown in a vertical stack. What is it primarily used for?

Creating a cleanout access point
Connecting a vent stack to a drain stack
Connecting horizontal drains at two levels
Serving two back-to-back fixtures such as two bathrooms on opposite sides of a wall (Correct answer)

Correct answer: Serving two back-to-back fixtures such as two bathrooms on opposite sides of a wall

A double sanitary tee installed in a vertical stack serves back-to-back fixtures on opposite sides of a wall, such as two bathroom groups.

Question 66: Which of the following is the most effective and code-approved method for protecting the potable water supply from contamination at a fixture by creating a physical separation?

Vacuum Breaker
Air Gap (Correct answer)
Check Valve
Air Break

Correct answer: Air Gap

An air gap is the unobstructed vertical space between the water supply outlet and the flood-level rim of a fixture. It is the most reliable and simplest form of backflow prevention because it creates a complete physical separation, preventing any contaminated water from siphoning back into the potable supply.

Question 67: In a DWV system, what does the term 'developed length' mean?

The vertical drop of a drain pipe
The diameter multiplied by the run length
The total length measured along the centerline of the pipe including fittings (Correct answer)
The straight-line distance between two points

Correct answer: The total length measured along the centerline of the pipe including fittings

Developed length is the total length measured along the centerline of the pipe, following all bends and offsets, used for calculating vent lengths and trap arm limits.

Question 68: Which of the following conditions ALWAYS requires a licensed plumber or gas fitter to obtain a permit before work begins?

Lighting a pilot light
Replacing an existing gas appliance connector (same size)
Cleaning a burner orifice
Installing new gas piping or extending an existing gas line (Correct answer)

Correct answer: Installing new gas piping or extending an existing gas line

Any new gas piping installation or extension of an existing gas system requires a permit to ensure the work is inspected and meets code.

Question 69: At what minimum storage temperature is Legionella bacteria effectively inhibited in a hot water system?

130°F (54°C)
110°F (43°C)
120°F (49°C)
140°F (60°C) (Correct answer)

Correct answer: 140°F (60°C)

Legionella bacteria are killed at 140°F (60°C); storing domestic hot water at or above this temperature prevents bacterial colonization and growth in the system.

Question 70: What is the federally mandated maximum flow rate for a standard showerhead manufactured after 1994, according to the Energy Policy Act?

2.0 GPM at 80 psi
3.0 GPM at 60 psi
2.5 GPM at 80 psi (Correct answer)
1.8 GPM at 80 psi

Correct answer: 2.5 GPM at 80 psi

The U.S. Energy Policy Act of 1992 (effective 1994) set the national maximum flow rate for showerheads at 2.5 gallons per minute (GPM) when tested at a pressure of 80 pounds per square inch (psi). While some states and programs like WaterSense have adopted lower rates, 2.5 GPM remains the federal standard.

Question 71: Which fixture requires a vented drain connection using a minimum 2-inch drain pipe per IPC?

Floor drain
Lavatory
Kitchen sink
Bathtub (Correct answer)

Correct answer: Bathtub

The IPC requires a minimum 1-1/2 inch drain for lavatories and kitchen sinks, but bathtubs require a minimum 1-1/2 inch drain; however, the drain fixture unit load typically requires 2 inches in many configurations — confirm with local amendments.

Question 72: Which fitting is prohibited in a concealed gas piping installation?

Mechanical press fittings listed for gas
Welded fittings
Wrought iron fittings
Flexible appliance connectors run through walls or floors (Correct answer)

Correct answer: Flexible appliance connectors run through walls or floors

Flexible appliance connectors must never be concealed in or run through walls, floors, or ceilings because they cannot be inspected or replaced easily.

Question 73: In an isometric plumbing drawing, a line drawn at 30° from horizontal typically represents which pipe orientation?

A vertical pipe
A pipe running diagonally in the building
A pipe running north-south or east-west in plan (Correct answer)
A pipe pitched for drainage

Correct answer: A pipe running north-south or east-west in plan

Lines drawn at 30° from horizontal on an isometric represent horizontal pipes running in plan view, either north-south or east-west.

Question 74: A manual shutoff valve must be installed within what distance of each gas appliance?

5 feet
3 feet
10 feet
6 feet (Correct answer)

Correct answer: 6 feet

The IFGC requires a manual shutoff valve to be installed within 6 feet of each gas appliance to allow for quick isolation in an emergency.

Question 75: When installing a pedestal lavatory, the drain rough-in height from the finished floor is typically:

18 inches
12 inches
24 inches
21 inches (Correct answer)

Correct answer: 21 inches

A pedestal lavatory drain rough-in is typically 21 inches from the finished floor to align with the fixture's drain outlet.

Question 76: Which of the following can circuit vents do?

Tie into stack vents
All of the above (Correct answer)
Tie into another vent that extends to outside air
Tie into vent stacks

Correct answer: All of the above

Ventilating a battery of fixtures requires the use of circuit vents. The vents might be connected to other vents that open to the outdoors. Vent stacks and stack vents are included in this. A circuit vent must have a diameter that is at least half that of the drain it is intended to serve.

Question 77: It is necessary for sewage pumps or sumps used to store sewage to be ________.

Covered with a gas-tight cover
Placed outside of any habitable structure
Both "vented" and "covered with a gas-tight cover" (Correct answer)
Vented

Correct answer: Both "vented" and "covered with a gas-tight cover"

It is necessary to vent sump sewage pumps that remove sanitary waste to the outside air. If a pneumatic sewer ejector pump is to be installed, the vent cannot be connected to a general venting system. The vent can be connected back to a common venting system when a standard sewer pump is to be used. A vent for a sewage sump will typically need to have a minimum diameter of two inches. Sewage sump coverings, in addition to effective venting, must be gas-tight.

Question 78: When a gas appliance is installed in a bedroom or bathroom, which special requirement applies?

No gas appliances are permitted in bedrooms or bathrooms
A CO detector must be installed within 1 foot of the appliance
The gas meter must be indoors
The appliance must be direct-vent or have a sealed combustion chamber (Correct answer)

Correct answer: The appliance must be direct-vent or have a sealed combustion chamber

Gas appliances in sleeping rooms and bathrooms must use direct-vent or sealed combustion systems to prevent combustion air from being drawn from the occupied space.

Question 79: Which fitting type is prohibited for use in a horizontal-to-horizontal drain change of direction?

Long-sweep 90-degree elbow
Combination wye-and-eighth bend
Wye fitting
Sanitary tee used on its side (Correct answer)

Correct answer: Sanitary tee used on its side

A sanitary tee used in a horizontal plane (on its side) does not provide proper flow direction and is prohibited for horizontal drainage.

Question 80: What is the maximum vertical drop allowed for a trap arm before it connects to the vent?

One pipe diameter
6 inches regardless of pipe size
The trap arm must slope but cannot drop more than the pipe diameter (Correct answer)
There is no vertical drop allowed; trap arms must be horizontal

Correct answer: The trap arm must slope but cannot drop more than the pipe diameter

A trap arm must slope toward the drain but cannot drop more than one pipe diameter in total vertical drop before reaching the vent connection.

Question 81: When sizing a gas piping system, the pressure drop allowed in a low-pressure system (under 2 psi) from the meter to the appliance is typically:

2.0 inch WC
0.5 inch WC (Correct answer)
1.0 inch WC
0.1 inch WC

Correct answer: 0.5 inch WC

For low-pressure systems, NFPA 54 sizing tables are based on a 0.5 inch WC pressure drop from the meter to the most remote appliance.

Journeyman Plumber Exam

The Journeyman Plumber Exam exam validates essential knowledge and skills required for certification or licensure in this field.

Questions

120 min

Time Limit

70%

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