Michigan Plumbing Contractor Practice
Exam
120 Questions with Answers & Rationales
1. Which code forms the basis for plumbing installations in Michigan?
A. The International Plumbing Code as amended by the Michigan Plumbing Code
B. The Uniform Plumbing Code with no state amendments
C. The National Standard Plumbing Code only
D. Local municipal codes with no state code
Answer: A
Rationale: Michigan adopts the International Plumbing Code (IPC) with state-specific
amendments, published as the Michigan Plumbing Code, which governs plumbing
work statewide.
2. A 'fixture unit' is best described as:
A. A measure of the probable discharge or demand a fixture places on a system
B. The physical size of a fixture in cubic feet
C. The number of fixtures in a bathroom group
D. The horsepower rating of a pump serving the fixture
Answer: A
Rationale: A fixture unit (drainage or water supply) is a relative value assigned to a
fixture representing its probable load, used to size piping.
,3. The term 'air gap' in plumbing refers to:
A. The unobstructed vertical distance between a supply outlet and the flood level
rim of a receptor
B. The space inside a vent stack
C. A trap seal depth
D. The clearance around a water heater
Answer: A
Rationale: An air gap is the vertical physical separation between the outlet of a water
supply and the flood-level rim of the fixture it serves, preventing backflow by eliminating
any possible connection.
4. A 'potable water' supply is defined as water that:
A. Is satisfactory for drinking, culinary, and domestic purposes
B. Has been treated only for irrigation use
C. Is used solely for fire suppression
D. Contains additives for industrial processes
Answer: A
Rationale: Potable water meets the health and quality requirements for drinking and
domestic use as established by the jurisdiction's health authority.
5. Under the Michigan Plumbing Code, who is generally authorized to enforce
plumbing code compliance?
A. The local or state plumbing inspector/code official
B. Any licensed contractor on the job
C. The property owner exclusively
D. The material supplier
Answer: A
Rationale: Enforcement authority rests with the code official (state or local plumbing
inspector) charged with administering and enforcing the plumbing code.
,6. A 'developed length' of pipe is:
A. The length along the centerline of the pipe and fittings
B. The straight-line distance between two points regardless of routing
C. The nominal diameter multiplied by the run length
D. The length measured only on horizontal runs
Answer: A
Rationale: Developed length follows the actual centerline path of the piping, including
all fittings and offsets, not a straight-line measurement.
7. What does 'trap seal' refer to?
A. The vertical depth of water retained in a trap that prevents sewer gas from
entering a building
B. The mechanical fastening of a trap to a fixture
C. A gasket used at trap connections
D. The distance a trap is offset from a wall
Answer: A
Rationale: Trap seal is the water retained in a trap that forms a barrier against the
passage of sewer gases into occupied spaces, typically required to be 2 to 4 inches
deep.
8. A 'combination waste and vent system' is typically used for:
A. Floor drains and indirect waste fixtures where conventional venting is impractical
B. High-rise residential bathroom groups
C. Storm water conductors only
D. Fire sprinkler drainage
Answer: A
Rationale: Combination waste and vent systems are used in special circumstances,
such as floor drains or fixtures without individual vents, using oversized drain piping to
admit air.
, 9. The minimum slope for a 2 1/2-inch or smaller horizontal drainage pipe is
generally:
A. 1/4 inch per foot
B. 1/8 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
Answer: A
Rationale: Horizontal drain piping 2 1/2 inches and smaller must generally slope a
minimum of 1/4 inch per foot toward the point of disposal.
10. Horizontal drainage piping 3 inches to 6 inches in diameter must slope at a
minimum of:
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. No slope is required
Answer: A
Rationale: For pipe sizes 3 inches through 6 inches, code permits a reduced minimum
slope of 1/8 inch per foot due to the larger flow capacity.
11. What is the purpose of a cleanout in a drainage system?
A. To provide access for clearing obstructions in the piping
B. To vent sewer gases to the atmosphere
C. To regulate water pressure
D. To measure water flow rate
Answer: A
Rationale: Cleanouts provide accessible points to rod out and clear blockages from the
drainage system without cutting into piping.
Exam
120 Questions with Answers & Rationales
1. Which code forms the basis for plumbing installations in Michigan?
A. The International Plumbing Code as amended by the Michigan Plumbing Code
B. The Uniform Plumbing Code with no state amendments
C. The National Standard Plumbing Code only
D. Local municipal codes with no state code
Answer: A
Rationale: Michigan adopts the International Plumbing Code (IPC) with state-specific
amendments, published as the Michigan Plumbing Code, which governs plumbing
work statewide.
2. A 'fixture unit' is best described as:
A. A measure of the probable discharge or demand a fixture places on a system
B. The physical size of a fixture in cubic feet
C. The number of fixtures in a bathroom group
D. The horsepower rating of a pump serving the fixture
Answer: A
Rationale: A fixture unit (drainage or water supply) is a relative value assigned to a
fixture representing its probable load, used to size piping.
,3. The term 'air gap' in plumbing refers to:
A. The unobstructed vertical distance between a supply outlet and the flood level
rim of a receptor
B. The space inside a vent stack
C. A trap seal depth
D. The clearance around a water heater
Answer: A
Rationale: An air gap is the vertical physical separation between the outlet of a water
supply and the flood-level rim of the fixture it serves, preventing backflow by eliminating
any possible connection.
4. A 'potable water' supply is defined as water that:
A. Is satisfactory for drinking, culinary, and domestic purposes
B. Has been treated only for irrigation use
C. Is used solely for fire suppression
D. Contains additives for industrial processes
Answer: A
Rationale: Potable water meets the health and quality requirements for drinking and
domestic use as established by the jurisdiction's health authority.
5. Under the Michigan Plumbing Code, who is generally authorized to enforce
plumbing code compliance?
A. The local or state plumbing inspector/code official
B. Any licensed contractor on the job
C. The property owner exclusively
D. The material supplier
Answer: A
Rationale: Enforcement authority rests with the code official (state or local plumbing
inspector) charged with administering and enforcing the plumbing code.
,6. A 'developed length' of pipe is:
A. The length along the centerline of the pipe and fittings
B. The straight-line distance between two points regardless of routing
C. The nominal diameter multiplied by the run length
D. The length measured only on horizontal runs
Answer: A
Rationale: Developed length follows the actual centerline path of the piping, including
all fittings and offsets, not a straight-line measurement.
7. What does 'trap seal' refer to?
A. The vertical depth of water retained in a trap that prevents sewer gas from
entering a building
B. The mechanical fastening of a trap to a fixture
C. A gasket used at trap connections
D. The distance a trap is offset from a wall
Answer: A
Rationale: Trap seal is the water retained in a trap that forms a barrier against the
passage of sewer gases into occupied spaces, typically required to be 2 to 4 inches
deep.
8. A 'combination waste and vent system' is typically used for:
A. Floor drains and indirect waste fixtures where conventional venting is impractical
B. High-rise residential bathroom groups
C. Storm water conductors only
D. Fire sprinkler drainage
Answer: A
Rationale: Combination waste and vent systems are used in special circumstances,
such as floor drains or fixtures without individual vents, using oversized drain piping to
admit air.
, 9. The minimum slope for a 2 1/2-inch or smaller horizontal drainage pipe is
generally:
A. 1/4 inch per foot
B. 1/8 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
Answer: A
Rationale: Horizontal drain piping 2 1/2 inches and smaller must generally slope a
minimum of 1/4 inch per foot toward the point of disposal.
10. Horizontal drainage piping 3 inches to 6 inches in diameter must slope at a
minimum of:
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. No slope is required
Answer: A
Rationale: For pipe sizes 3 inches through 6 inches, code permits a reduced minimum
slope of 1/8 inch per foot due to the larger flow capacity.
11. What is the purpose of a cleanout in a drainage system?
A. To provide access for clearing obstructions in the piping
B. To vent sewer gases to the atmosphere
C. To regulate water pressure
D. To measure water flow rate
Answer: A
Rationale: Cleanouts provide accessible points to rod out and clear blockages from the
drainage system without cutting into piping.
