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100+ Free MS Residential Plumbing Practice Questions

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2026 Statistics

Key Facts: MS Residential Plumbing Exam

70%

Passing Score

PSI MS Contractor Bulletin 4/23/2026

80 Q

Official Exam Questions

PSI MS Contractor Bulletin 4/23/2026

4 hours

Time Allowed

PSI MS Contractor Bulletin 4/23/2026

$120

PSI Exam Fee

PSI MS Contractor Bulletin 4/23/2026

Open book

Exam Format

PSI MS Contractor Bulletin 4/23/2026

MS Residential Plumbing PSI trade exam: 80 questions, 70% pass, 4 hours, fee $120. Open-book MSBOC classification (bulletin 4/23/2026).

Sample MS Residential Plumbing Practice Questions

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

1Under the 2021 International Plumbing Code (IPC), when must a plumbing system be tested and inspected relative to concealment?
A.After finish materials are installed so leaks are easier to see
B.Before any portion of the system is concealed or covered
C.Only after the building sewer is connected to the public main
D.Only if the system contains more than 20 drainage fixture units
Explanation: IPC Chapter 3 requires the permit holder to test drainage, vent, and water-supply piping and to give the code official notice when the work is ready. Rough piping must be proven tight before it is concealed so that joints, hangers, and fittings can be seen and repaired. Covering work before inspection is a common cause of failed inspections and rework.
2A Mississippi residential plumbing contractor is installing a new water heater. Per IPC 301.7, if the manufacturer's installation instructions conflict with a minimum code provision, which requirement applies?
A.The manufacturer's instructions always control
B.The less expensive of the two methods may be used
C.The more restrictive provisions apply
D.The contractor may choose either method if both are listed
Explanation: IPC 301.7 states that where the code and the manufacturer's installation instructions conflict, the more restrictive provisions apply. The installer must still follow listing and labeling requirements, but a looser manufacturer note does not waive a stricter code minimum such as relief-valve discharge or clearances.
3Which statement best describes how the 2021 International Residential Code (IRC) plumbing chapters relate to a one- and two-family dwelling that is also subject to the 2021 IPC on the Mississippi PSI bulletin?
A.The IRC plumbing chapters apply only to commercial kitchens
B.The IRC plumbing provisions are written for dwellings and are used together with the IPC, IFGC, and OSHA references listed for the exam
C.The IRC automatically voids every IPC table for residential work
D.Only the IFGC applies to residential plumbing; the IRC is structural only
Explanation: The PSI Mississippi contractor bulletin lists OSHA 29 CFR 1926, IPC 2021, IFGC 2018, and IRC 2021 as the approved technical references for the Residential Plumbing classification. IRC plumbing chapters (P25–P32) and fuel-gas/oil chapters cover one- and two-family dwellings. Candidates should stay inside the listed edition of each book rather than mixing Uniform Plumbing Code or an older IPC.
4Per IPC 604.8, a pressure-reducing valve is required when static water pressure at the building exceeds which value?
A.60 psi
B.80 psi
C.100 psi
D.125 psi
Explanation: IPC 604.8 requires an approved pressure-reducing valve, with a strainer on the inlet, where water pressure exceeds 80 psi. The valve limits static pressure in the building distribution system so fixture valves, tank toilets, and joints are not overstressed. 60 psi is a common comfortable operating pressure, but it is not the code trigger.
5A 2-inch PVC DWV stack is ready for a rough drainage test. Per IPC 312.2 and 312.3, which test method is acceptable?
A.A 5 psi air test held for 15 minutes
B.A water test with not less than a 10-foot head held for 15 minutes
C.A soap-bubble wipe of each joint with the system at atmospheric pressure
D.A 50 psi air test held for 15 minutes
Explanation: IPC 312.2 allows a water test of the drainage and vent system in its entirety or in sections, with each section under not less than a 10-foot head of water for at least 15 minutes. IPC 312.3 expressly prohibits air testing of plastic piping. PVC DWV must therefore be water-tested, not air-tested.
6Upon completion of a copper water-distribution system, IPC 312.5 requires the system to be proven tight under which condition?
A.A water test at not less than the working pressure of the system, or an air test of not less than 50 psi, held for at least 15 minutes
B.A 5 psi air test held for 5 minutes
C.A visual inspection of solder joints only
D.A 10-foot head of water applied at the meter only
Explanation: IPC 312.5 requires a completed water-supply section or system to be tested at not less than the working pressure with water, or, for piping other than plastic, by an air test of not less than 50 psi. Either test is held at least 15 minutes, and test water must come from a potable source.
7Per IPC 312.1, who is responsible for furnishing the equipment, material, power, and labor needed to perform the required plumbing tests?
A.The code official
B.The water utility
C.The permit holder
D.The property insurer
Explanation: IPC 312.1 assigns the required tests to the permit holder. The permit holder must give reasonable notice when the work is ready, furnish the equipment, material, power, and labor, and determine that the work will withstand the prescribed test pressure. The inspector observes; the contractor proves the system.
8A concealed 1/2-inch PEX water line is bored through a wood stud so that the edge of the hole is 1 inch from the face of the stud. Per IPC 305.6, what protection is required?
A.No protection is required because PEX is flexible
B.Steel shield plates not less than 0.0575 inch thick (No. 16 gage) covering the bored area and extending at least 2 inches above the sole plate and below the top plate
C.Plastic tape wrapped around the tubing at the stud
D.A wood block nailed over the hole on one side of the stud
Explanation: IPC 305.6 requires steel shield plates where piping other than cast iron or galvanized steel is installed through holes or notches less than 1-1/4 inches from the nearest edge of the member. Plates must be at least No. 16 gage (0.0575 inch), cover the pipe at the notch or hole, and extend not less than 2 inches above sole plates and below top plates so nails and screws miss the tube.
9Per IPC 301.3, which of the following may discharge through an approved indirect waste system instead of a direct sanitary connection?
A.A water closet
B.A urinal
C.Fixtures required by Chapter 8 to be indirectly wasted, such as food-handling equipment
D.A residential sewage ejector discharge
Explanation: IPC 301.3 requires plumbing fixtures, drains, and appliances that receive liquid waste or sewage to be directly connected to the sanitary drainage system, except that Chapter 8 indirect-waste systems are permitted where required. Food-handling equipment, dishwashers in some applications, and similar receptors use an air gap or air break so sewage cannot back into the fixture.
10IPC 1002.1 generally requires each plumbing fixture to be separately trapped, except where the code specifically allows a combination fixture. Which installation is prohibited?
A.A two-compartment laundry tray served by one trap
B.A kitchen sink and food-waste disposer sharing one trap
C.A lavatory discharging through a water-closet trap (double trapping)
D.A bathtub with its own 1-1/2-inch trap
Explanation: IPC 1002.1 requires a separate trap for each fixture unless a listed combination fixture is allowed. Discharging one fixture through another fixture's trap is double trapping. Double traps impede flow, retain waste, and are prohibited. A dedicated bathtub trap and certain combination sinks or laundry trays are permitted when they meet the section's limits.

About the MS Residential Plumbing Exam

Mississippi Residential Plumbing Contractor Examination is a classification trade examination administered by PSI for the Mississippi State Board of Contractors. The official open-book exam has 80 questions, a 70% passing standard, and 4 hours allowed. PSI examination fee is $120 per portion (bulletin updated 4/23/2026). This English-language MCQ bank is a study aid for the official content outline; it is not an official PSI form, does not replace the required Law and Business Management exam, and is not a substitute for MSBOC application review or the official open-book examination.

Questions

80 scored questions

Time Limit

4 hours

Passing Score

70%

Exam Fee

$120 (PSI Services LLC (for Mississippi State Board of Contractors))

MS Residential Plumbing Exam Content Outline

19%

General Plumbing Knowledge and Regulations

Residential plumbing regulations

8%

Piping, Valves, and Controls

Piping, valves, and controls

5%

Fixtures and Equipment

Fixtures

5%

Water Supply

Water supply

21%

Drain, Waste and Vent and Sewers

DWV and sewers

11%

Isometric Analysis

Isometric reading

5%

Safety

Plumbing safety

8%

Specialty Applications

Specialty residential plumbing

6%

Fuel Gas

Fuel gas

4%

LP Gas

LP-gas

3%

Fuel Oil

Fuel oil

6%

Piping

Additional piping topics

How to Pass the MS Residential Plumbing Exam

What You Need to Know

  • Passing score: 70%
  • Exam length: 80 questions
  • Time limit: 4 hours
  • Exam fee: $120

Keys to Passing

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

MS Residential Plumbing Study Tips from Top Performers

1Study only the approved references listed for this classification in the current PSI Mississippi Contractor bulletin (updated 4/23/2026)
2Practice open-book navigation with permanent tabs and indexes before test day
3Drill OSHA 29 CFR 1926 topics that appear across nearly every trade outline
4Confirm MSBOC classification scope and eligibility at msboc.us before scheduling with PSI
5All applicants must also pass Law and Business Management unless it is waived

Frequently Asked Questions

How many questions are on the MS Residential Plumbing exam?

The official PSI examination has 80 scored questions (plus possible unscored experimental items). Passing is 70% within 4 hours.

How much does the MS Residential Plumbing exam cost?

PSI lists $120 per examination portion (Candidate Information Bulletin updated 4/23/2026). MSBOC application fees are separate: $400 commercial or $50 residential. Additional classifications are $100 each.

Is the Mississippi contractor exam open book?

Yes. PSI administers MSBOC classification exams as open book. Only bulletin-listed approved references are allowed; temporary tabs such as Post-it notes are prohibited.

Do I still need the Law and Business Management exam?

Yes. MSBOC requires the Mississippi Law and Business Management exam (50 questions, 70%, 2 hours) of all applicants. Reciprocity may waive a trade exam in some cases but does not waive Law and Business.