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NC Plumbing Contractor practice questions

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Question 1Administration, Code Adoption, and Licensing Regulations

The North Carolina Plumbing Code is adopted from which model code?

  1. International Plumbing Code Correct answer.
  2. Uniform Plumbing Code
  3. National Standard Plumbing Code
  4. International Mechanical Code

Explanation

North Carolina adopts the International Plumbing Code by reference and then applies state amendments through the Building Code Council. The other documents listed are not the base code for plumbing in North Carolina.

Question 2Administration, Code Adoption, and Licensing Regulations

Which body has statutory authority to adopt the North Carolina State Building Code, including the Plumbing Code?

  1. The North Carolina Code Officials Qualification Board
  2. The State Board of Examiners of Plumbing, Heating and Fire Sprinkler Contractors
  3. The North Carolina Department of Labor
  4. The North Carolina Building Code Council Correct answer.

Explanation

The Building Code Council adopts and amends the North Carolina State Building Code, of which the Plumbing Code is a volume. The Board of Examiners handles contractor licensing, the Qualification Board certifies code officials, and the Department of Labor enforces occupational safety rules.

Question 3Administration, Code Adoption, and Licensing Regulations

A plumbing contractor is ready to begin the rough-in piping for a new commercial building. What must be obtained before that work starts?

  1. A plumbing permit from the local inspections department Correct answer.
  2. A certificate of occupancy issued by the building department
  3. A letter of intent signed by the property owner
  4. A variance from the State Board of Examiners

Explanation

A plumbing permit must be issued by the local inspections department before plumbing work begins so that the required inspections can be performed. A certificate of occupancy is issued only at the end of the project, after the work has been inspected and approved.

Question 4Administration, Code Adoption, and Licensing Regulations

North Carolina issues plumbing contractor licenses in which two classifications?

  1. P-1 (unlimited) and P-2 (limited) Correct answer.
  2. Master and Journeyman
  3. Residential and Commercial
  4. Class A and Class B

Explanation

The State Board of Examiners issues P-1 unlimited and P-2 limited plumbing contractor licenses. Master and journeyman designations refer to trade skill levels rather than to contractor license classifications.

Question 5Administration, Code Adoption, and Licensing Regulations

Rough-in plumbing has been installed in a new house. Before the piping is covered with drywall or backfill, the contractor must:

  1. Notify the State Board of Examiners in writing before covering the work
  2. Obtain an additional building permit for the concealment
  3. Request an inspection by the code enforcement official Correct answer.
  4. Submit complete as-built drawings to the Building Code Council

Explanation

Work that will be concealed must be inspected and approved while it is still exposed. The contractor is responsible for requesting that inspection before covering the piping.

Question 6Administration, Code Adoption, and Licensing Regulations

A plumbing contractor license issued by the State Board of Examiners must be renewed:

  1. Every three years
  2. Only when the contractor changes business address
  3. Annually Correct answer.
  4. Every five years

Explanation

Plumbing contractor licenses in North Carolina are renewed annually to remain in force. A change of address is a separate reporting obligation and does not control the renewal cycle.

Question 7Administration, Code Adoption, and Licensing Regulations

Plumbing inspectors and other code enforcement officials in North Carolina must be certified by which body?

  1. The State Board of Examiners of Plumbing, Heating and Fire Sprinkler Contractors
  2. The local board of adjustment
  3. The North Carolina Building Code Council
  4. The North Carolina Code Officials Qualification Board Correct answer.

Explanation

The Code Officials Qualification Board sets qualifications and certifies code enforcement officials, including plumbing inspectors. The Building Code Council adopts the code and the Board of Examiners licenses contractors.

Question 8Administration, Code Adoption, and Licensing Regulations

A newly formed plumbing company wants to contract for plumbing work. How does the licensing requirement apply to the company?

  1. The company must employ at least one journeyman plumber for every three apprentices
  2. The company must designate a licensed plumbing contractor as qualifier responsible for the work Correct answer.
  3. The company must obtain a corporate license directly from the Building Code Council
  4. The company registers its name with the Board and pays a fee, with no further requirement

Explanation

North Carolina licenses individuals, not business entities. A company that contracts for plumbing work must have a licensed plumbing contractor serving as its qualifier and responsible for the work.

Question 9Administration, Code Adoption, and Licensing Regulations

A building permit has been issued for a new restaurant. Which statement about the plumbing work is correct?

  1. A plumbing permit is needed only if a water heater is being replaced
  2. No plumbing permit is required for interior tenant improvement work
  3. A separate plumbing permit must be obtained for the plumbing work Correct answer.
  4. The building permit also authorizes all plumbing work covered by the plans

Explanation

A building permit does not authorize plumbing work; a separate plumbing permit is required from the inspections department. This allows the plumbing work to be inspected by the appropriate trade inspector.

Question 10Administration, Code Adoption, and Licensing Regulations

A city council proposes a local plumbing ordinance that would allow a smaller vent size than the state code requires. Which statement is correct?

  1. It applies only to residential buildings located within the city limits
  2. It is invalid, because local standards may not be less stringent than the state code Correct answer.
  3. It takes effect only after approval by the State Board of Examiners and the Council
  4. It is valid, because cities have broad home rule authority over construction standards within their limits

Explanation

The North Carolina State Building Code sets a statewide minimum, and local governments may not adopt standards less stringent than the state code. A local ordinance that weakens a plumbing requirement is therefore unenforceable.

Question 11Administration, Code Adoption, and Licensing Regulations

A contractor disagrees with the local plumbing inspector's interpretation of a code provision. Where is the appeal filed?

  1. The local board of adjustment Correct answer.
  2. The North Carolina Court of Appeals
  3. The State Board of Examiners of Plumbing, Heating and Fire Sprinkler Contractors
  4. The International Code Council

Explanation

Appeals of code enforcement decisions are heard by the local board of adjustment, which is the quasi-judicial body established for that purpose. The Board of Examiners deals with licensing matters, and the model code publisher has no appellate authority.

Question 12Administration, Code Adoption, and Licensing Regulations

Plumbing contractor licensing in North Carolina is governed primarily by which chapter of the General Statutes?

  1. Chapter 87 Correct answer.
  2. Chapter 143
  3. Chapter 150B
  4. Chapter 160A

Explanation

Chapter 87 of the North Carolina General Statutes contains the licensing laws for plumbing, heating, and fire sprinkler contractors. Chapter 143 covers state departments and the building code, Chapter 150B governs administrative procedure, and Chapter 160A applies to cities.

Question 13Administration, Code Adoption, and Licensing Regulations

A person who engages in the business of plumbing contracting without a license is:

  1. Entitled to a provisional license while awaiting examination
  2. Subject to criminal penalty and Board enforcement action Correct answer.
  3. Required only to register with the local inspections department within 30 days
  4. In compliance, provided all of the work passes the required inspections

Explanation

Contracting without a license violates Chapter 87 and exposes the person to criminal penalty as well as enforcement action by the Board. Passing inspections does not cure the failure to hold a license.

Question 14Administration, Code Adoption, and Licensing Regulations

Which of the following is required to obtain a plumbing contractor license from the State Board of Examiners?

  1. A performance bond filed with the county register of deeds
  2. Passing the Board's licensing examination Correct answer.
  3. A corporate charter filed with the Building Code Council
  4. Membership in a statewide plumbing trade association

Explanation

An applicant must satisfy the Board's experience and character requirements and pass the licensing examination for the classification sought. Trade association membership and local filings are not licensing requirements.

Question 15Administration, Code Adoption, and Licensing Regulations

The State Board of Examiners may discipline a licensee who violates the licensing law or the plumbing code by:

  1. Amending the state plumbing code to address the violation at issue
  2. Issuing a stop-work order at the job site until the violation is fixed
  3. Revoking or suspending the license after notice and a hearing Correct answer.
  4. Assessing criminal fines in superior court against the licensee

Explanation

The Board's disciplinary authority includes revoking, suspending, or refusing to renew a license after proper notice and hearing. Stop-work orders and criminal fines are handled by local code officials and the courts, not by the Board.

Question 16Administration, Code Adoption, and Licensing Regulations

Before a certificate of occupancy is issued for a newly constructed building, the plumbing work must:

  1. Be inspected and approved by the code enforcement official Correct answer.
  2. Remain uncovered for one year after completion
  3. Be reviewed and approved in advance by the State Board of Examiners
  4. Be photographed and filed with the Building Code Council

Explanation

A certificate of occupancy requires that the plumbing work receive final inspection approval from the code enforcement official. The Board of Examiners and the Building Code Council are not part of that job-site approval process.

Question 17Administration, Code Adoption, and Licensing Regulations

A plumbing contractor licensed in another state whose requirements are substantially equivalent to North Carolina's applies for a North Carolina license. What may the Board do?

  1. Issue a license without examination based on reciprocity Correct answer.
  2. Require the applicant to serve as an apprentice for two additional years
  3. Waive the licensing requirement entirely for the contractor's current project
  4. Issue only a P-2 limited license regardless of the applicant's qualifications

Explanation

The Board may grant a license by reciprocity to a licensee of another jurisdiction whose licensing requirements are substantially equivalent. Reciprocity does not waive licensure itself, nor does it automatically restrict the applicant to a limited classification.

Question 18Administration, Code Adoption, and Licensing Regulations

A firm holds a P-2 limited plumbing license and is invited to bid work that exceeds the scope limitation of that classification. What is the proper action?

  1. Proceed if a P-1 licensee supervises the work part-time
  2. Decline the work or qualify for a P-1 unlimited license Correct answer.
  3. Proceed, because P-1 and P-2 licenses carry the same authority
  4. Proceed if the local code enforcement official approves the plans

Explanation

A P-2 license authorizes only work within the limited scope of that classification, so contracting beyond it is outside the license's authority. The firm must decline the work or obtain the appropriate P-1 unlimited license.

Question 19Administration, Code Adoption, and Licensing Regulations

A local ordinance on plumbing vent sizing conflicts with the North Carolina Plumbing Code, and the ordinance is less stringent. Which provision controls?

  1. The state code, because it applies uniformly throughout North Carolina Correct answer.
  2. The local ordinance, if it was passed after the state code took effect
  3. The more recent of the two provisions, whichever document that may be
  4. The code enforcement official's judgment in each individual case

Explanation

The state code establishes a uniform minimum standard that applies statewide, and a less stringent local provision cannot override it. Enforcement officials must apply the state code rather than choose between conflicting provisions case by case.

Question 20Administration, Code Adoption, and Licensing Regulations

The individual whose license qualifies a plumbing business leaves the company. What must the business do to keep contracting lawfully?

  1. Transfer the departed individual's license into the company's name
  2. Continue operating under the departed individual's license until the next renewal date
  3. Operate under a provisional authority granted automatically for one year
  4. Designate another licensed plumbing contractor as qualifier for the business Correct answer.

Explanation

Because the license belongs to the individual and qualifies the business, the business loses its authority to contract when that individual leaves. It must designate another licensed plumbing contractor as qualifier before continuing to contract.

Question 21General Building and Plumbing Code Requirements, Definitions, and Standards

What is the minimum depth of liquid seal required for a plumbing fixture trap?

  1. 1 inch
  2. 2 inches Correct answer.
  3. 4 inches
  4. 6 inches

Explanation

IPC 1002.4 requires each fixture trap to maintain a liquid seal of not less than 2 inches and not more than 4 inches. A shallower seal can be broken by siphonage or back pressure, while a deeper seal retains more putrescible waste than necessary.

Question 22General Building and Plumbing Code Requirements, Definitions, and Standards

Horizontal drainage piping 3 inches in diameter or smaller must be installed at a minimum slope of:

  1. 1/8 inch per foot
  2. 3/4 inch per foot
  3. 1/4 inch per foot Correct answer.
  4. 1/2 inch per foot

Explanation

IPC 704.1 requires horizontal drainage pipe 3 inches and smaller to be graded at not less than 1/4 inch per foot (2 percent). The 1/8 inch per foot slope is permitted only for pipe 4 inches and larger.

Question 23General Building and Plumbing Code Requirements, Definitions, and Standards

A cleanout installed on a 4-inch building drain must be not less than:

  1. 4 inches Correct answer.
  2. 3 inches
  3. 6 inches
  4. 2 inches

Explanation

IPC 708.3 requires the cleanout to be the same nominal size as the pipe it serves, up to 4 inches. For pipe larger than 4 inches, a 4-inch cleanout is the minimum permitted.

Question 24General Building and Plumbing Code Requirements, Definitions, and Standards

A temperature and pressure relief valve on a storage water heater must be installed:

  1. on the hot water outlet piping at least 12 inches from the tank
  2. on the cold water inlet piping within 12 inches of the tank
  3. within the top 6 inches of the tank Correct answer.
  4. on the drain valve at the bottom of the tank

Explanation

IPC 504.4 requires the relief valve to be installed within the top 6 inches of the tank, where the hottest water collects. The valve must be sized to the tank rating and must not be valved off or plugged.

Question 25General Building and Plumbing Code Requirements, Definitions, and Standards

Potable water is defined as water that is:

  1. free from impurities that can cause disease or harmful effects Correct answer.
  2. water that has been softened and chlorinated before delivery
  3. surface water that has been filtered through a sand bed
  4. suitable only for flushing water closets and urinals

Explanation

The plumbing code defines potable water as water free from impurities present in amounts sufficient to cause disease or harmful physiological effects. Its bacteriological and chemical quality must conform to the public health standards referenced by the code.

Question 26General Building and Plumbing Code Requirements, Definitions, and Standards

The air gap between a potable water supply outlet and the flood level rim of a fixture must be:

  1. one-half the diameter of the supply pipe
  2. twice the effective opening, but not less than 1 inch Correct answer.
  3. equal to the diameter of the supply outlet plus one pipe size
  4. four times the effective opening of the outlet

Explanation

An air gap is the unobstructed vertical distance through free atmosphere between the lowest outlet and the flood level rim. The code requires it to be at least twice the effective opening of the outlet and never less than 1 inch.

Question 27General Building and Plumbing Code Requirements, Definitions, and Standards

The maximum developed length of a 2-inch trap arm measured from the trap weir to the vent, where the arm is graded at 1/4 inch per foot, is:

  1. 8 feet Correct answer.
  2. 12 feet
  3. 5 feet
  4. 6 feet

Explanation

IPC Table 1002.2 limits a 2-inch trap arm to 8 feet of developed length at a 1/4 inch per foot slope. The limit exists so the arm cannot fill more than its diameter and choke off the vent.

Question 28General Building and Plumbing Code Requirements, Definitions, and Standards

The minimum residual pressure required at a fixture supply is:

  1. 8 psi for flush tanks and 15 psi for flushometer valves Correct answer.
  2. 15 psi for all fixtures in the building
  3. 15 psi for flush tanks and 8 psi for flushometer valves
  4. 20 psi at all fixtures regardless of type

Explanation

The code sets minimum residual pressures of 8 psi at flush tanks and 15 psi at flushometer valves, measured while the fixture is flowing. Distribution piping must be sized so these pressures remain available at peak demand.

Question 29General Building and Plumbing Code Requirements, Definitions, and Standards

A horizontal drainage line must connect to another horizontal drainage line by means of:

  1. a double sanitary tee installed vertically
  2. a short-sweep quarter bend alone
  3. a single sanitary tee with a 2-inch outlet
  4. a wye branch or combination wye and eighth bend Correct answer.

Explanation

IPC 706.1 requires horizontal-to-horizontal drainage connections to be made with a wye branch or a combination wye and eighth bend. Sanitary tees are prohibited in this position because they turn the flow abruptly and promote clogging.

Question 30General Building and Plumbing Code Requirements, Definitions, and Standards

A drain pan is required under a storage water heater:

  1. whenever the heater is installed above a concrete floor
  2. only when the heater is installed in an unconditioned attic space
  3. where leakage from the heater could cause damage to the building Correct answer.
  4. only when the water heater exceeds 100 gallons in capacity

Explanation

IPC 504.7 requires a drain pan where a water heater is installed in a location where leakage could cause damage to the building or its contents. The pan must be at least 1-1/2 inches deep and drained by a pipe of at least 3/4 inch.

Question 31General Building and Plumbing Code Requirements, Definitions, and Standards

The minimum nominal size permitted for any plumbing vent pipe is:

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

Explanation

Vent piping is sized from the code tables but may never be smaller than 1-1/4 inch nominal. Smaller vents are not recognized because they clog readily and cannot relieve the drainage system.

Question 32General Building and Plumbing Code Requirements, Definitions, and Standards

Vertical drainage and vent piping must be supported at intervals not exceeding:

  1. 15 feet Correct answer.
  2. 4 feet
  3. 6 feet
  4. 10 feet

Explanation

IPC 308.1 limits vertical pipe support spacing to 15 feet, with a support required at each story or floor level as applicable. Horizontal plastic drainage pipe is supported much more closely, typically every 4 feet.

Question 33General Building and Plumbing Code Requirements, Definitions, and Standards

The drainage fixture unit value assigned to a private lavatory is:

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

Explanation

Under the fixture unit table, a private lavatory carries a drainage load of 1 fixture unit. A water closet carries substantially more, which is why bathroom groups are computed from the table rather than by fixture count.

Question 34General Building and Plumbing Code Requirements, Definitions, and Standards

An exterior sill cock connected to the potable water system must be protected against backflow by:

  1. a dual check valve installed inside the building
  2. a check valve at the water meter
  3. a pressure-reducing valve at the main
  4. a hose-connection vacuum breaker Correct answer.

Explanation

The code requires hose bibbs and sill cocks to be protected by a vacuum breaker, either an integral hose-connection type or an atmospheric type. This prevents a submerged hose from siphoning contaminants into the potable supply.

Question 35General Building and Plumbing Code Requirements, Definitions, and Standards

The building drain is the lowest piping of a drainage system and it terminates:

  1. at the first manhole downstream of the building
  2. at the property line or private sewage disposal system
  3. 5 feet from the building foundation
  4. 30 inches outside the building wall Correct answer.

Explanation

By definition, the building drain receives the discharge from drainage pipe inside the building and extends to a point 30 inches outside the building wall. Beyond that point the piping is the building sewer.

Question 36General Building and Plumbing Code Requirements, Definitions, and Standards

The minimum size of a fixture drain serving a water closet is:

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

Explanation

A water closet must be served by a drain of at least 3 inches in diameter to carry the solids discharged. General fixture drains may be as small as 1-1/4 inch, but the water closet is specifically sized larger.

Question 37General Building and Plumbing Code Requirements, Definitions, and Standards

An air admittance valve may be used as a vent only where:

  1. the building is three stories or less in height
  2. the valve is installed in a concealed wall cavity for protection
  3. at least one vent extends outdoors and the valve remains accessible Correct answer.
  4. each fixture drain is individually trapped and vented

Explanation

Air admittance valves admit air to relieve vacuum but do not relieve positive pressure, so the system must still have at least one vent terminating outdoors. The valve must be accessible for service and installed per the listing.

Question 38General Building and Plumbing Code Requirements, Definitions, and Standards

When a water test is used on a new drainage system, the piping must withstand a head of water of:

  1. 5 feet for 30 minutes
  2. 3 feet for 1 hour
  3. 10 feet for 15 minutes Correct answer.
  4. 20 feet for 1 hour

Explanation

IPC 312.3 requires a water test consisting of a 10-foot head of water maintained for 15 minutes before inspection. The test may also be performed with air under the pressures and time specified in the code.

Question 39General Building and Plumbing Code Requirements, Definitions, and Standards

The minimum nominal size of a water service pipe is:

  1. 5/8 inch
  2. 1/2 inch
  3. 3/4 inch Correct answer.
  4. 1 inch

Explanation

The water service pipe must be sized from the demand tables but may not be smaller than 3/4 inch nominal. This minimum ensures adequate capacity and limits excessive velocity and pressure loss.

Question 40General Building and Plumbing Code Requirements, Definitions, and Standards

A reduced pressure principle backflow prevention assembly installed on a potable water line must be tested for proper operation:

  1. at least annually Correct answer.
  2. every 5 years
  3. every 3 years
  4. only when it is first installed

Explanation

Reduced pressure principle assemblies must be tested at least once each year by a certified tester, with results reported to the water purveyor. The annual test confirms that both check valves and the relief valve function correctly.

Question 41General Building and Plumbing Code Requirements, Definitions, and Standards

The maximum drainage load permitted on a 4-inch horizontal drainage pipe graded at 1/4 inch per foot is:

  1. 160 fixture units
  2. 500 fixture units
  3. 90 fixture units
  4. 216 fixture units Correct answer.

Explanation

Under the drainage capacity table, a 4-inch pipe at 1/4 inch per foot slope carries a maximum of 216 fixture units. Capacity decreases at shallower slopes, which is why steeper pipe can handle more load.

Question 42General Building and Plumbing Code Requirements, Definitions, and Standards

The discharge pipe from a sewage ejector pump must be not less than:

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

Explanation

The code requires a sewage pump discharge of at least 2 inches, fitted with an accessible check valve and a gate valve. The pit must also be vented and sealed to control odors.

Question 43General Building and Plumbing Code Requirements, Definitions, and Standards

A thermal expansion tank is required on a water heater installation when:

  1. a check valve or backflow preventer is installed on the cold water supply Correct answer.
  2. the building is served by a public water system rather than a well
  3. the water heater is installed with a continuous recirculation loop
  4. the heater is located above the highest fixture in the building

Explanation

A check valve, backflow preventer, or pressure-reducing valve creates a closed system in which thermally expanded water has nowhere to go. A thermal expansion tank absorbs that volume and protects the tank and relief valve.

Question 44General Building and Plumbing Code Requirements, Definitions, and Standards

The clear space in front of a water closet, measured from the front of the bowl to a wall or obstruction, must be not less than:

  1. 12 inches
  2. 21 inches Correct answer.
  3. 18 inches
  4. 15 inches

Explanation

IPC 405.3.1 requires at least 21 inches of clearance in front of a water closet and at least 15 inches from its centerline to a sidewall. These dimensions provide usable space and access for cleaning.

Question 45Drainage, Waste, and Vent Systems

What is the minimum required depth of a fixture trap seal?

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

Explanation

A trap must hold a water seal of at least 2 inches, measured from the trap weir to the top of the dip, to keep sewer gas out of the building. The same rule caps the seal at 4 inches so the trap stays self-cleaning.

Question 46Drainage, Waste, and Vent Systems

What is the maximum permitted depth of a fixture trap seal?

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

Explanation

Trap seals are limited to 4 inches so the trap remains self-cleaning and does not hold an excessive volume of waste. The minimum seal depth is 2 inches.

Question 47Drainage, Waste, and Vent Systems

What is the minimum slope for a 3-inch horizontal drainage pipe?

  1. 1/4 inch per foot
  2. 1/2 inch per foot
  3. 1/8 inch per foot Correct answer.
  4. 1/16 inch per foot

Explanation

Horizontal drainage pipe from 3 inches through 6 inches in diameter may be installed at a minimum slope of 1/8 inch per foot. Pipe 2-1/2 inches and smaller must be sloped at least 1/4 inch per foot.

Question 48Drainage, Waste, and Vent Systems

The building drain ends at what distance beyond the exterior wall of the building?

  1. 12 inches
  2. 30 inches Correct answer.
  3. 60 inches
  4. 24 inches

Explanation

The building drain is defined as the lowest piping that conveys waste to a point 30 inches outside the building wall. Beyond that point the pipe becomes the building sewer and is regulated differently.

Question 49Drainage, Waste, and Vent Systems

A vent stack that terminates through a roof must extend at least how far above the roof surface?

  1. 12 inches
  2. 18 inches
  3. 24 inches
  4. 6 inches Correct answer.

Explanation

Vent terminals must extend not less than 6 inches above the roof and be flashed to keep the penetration watertight. Greater heights are required where the roof is used for purposes other than weather protection.

Question 50Drainage, Waste, and Vent Systems

A gravity-tank water closet is assigned how many drainage fixture units (DFU)?

  1. 1
  2. 3 Correct answer.
  3. 2
  4. 4

Explanation

In the standard fixture-unit table a water closet is rated at 3 DFU, while a lavatory is rated at 1 DFU and a bathtub or shower at 2 DFU. These values are used to size the drain and vent serving the fixtures.