SLB Plumbing Contractor Examination
Questions With Answers and Explanations
Question 1. Near substantial completion, remaining minor deficiencies and incomplete items are
documented for correction. What is this list called?
A. A gas manifold schedule
B. A hot-work permit
C. A fixture-unit table
D. A punch list
Correct Answer: D. A punch list
Explanation: A punch list is the best answer because a punch list identifies incomplete or deficient work that must be
corrected before final closeout. Successful plumbing projects combine complete scope review, realistic labor and material
estimates, documented changes, and disciplined schedule control. The other choices address different system functions
and would not resolve the condition described. Clear records and timely communication reduce disputes, rework, and
unplanned cost.
Question 2. A pipe run rises 18 inches over a horizontal distance of 24 feet. What is the average rise per
foot?
A. 1.33 inches per foot
B. 0.25 inch per foot
C. 1.5 inches per foot
D. 0.75 inch per foot
Correct Answer: D. 0.75 inch per foot
Explanation: 0.75 inch per foot is the best answer because 18 inches divided by 24 feet equals 0.75 inch of rise per foot.
Accurate takeoffs and sizing depend on reading plans correctly, applying the stated scale, and using consistent units and
formulas. Choosing among these options requires matching the system function to the actual hazard, load, or field
condition. Calculated values should be checked for reasonableness before they are used for procurement or field layout.
Original practice material • Verify local code edition and amendments Page 1
,SLB Plumbing Contractor Examination — 600 Practice Questions
Question 3. A primary roof drain becomes blocked during a heavy storm. What feature is intended to
limit dangerous ponding?
A. An independent secondary drainage or overflow path
B. A gas sediment trap
C. A larger domestic water meter
D. A sanitary trap primer
Correct Answer: A. An independent secondary drainage or overflow path
Explanation: An independent secondary drainage or overflow path is the best answer because secondary drainage
provides an alternate path when primary drainage is obstructed so roof water does not rise to unsafe levels. Storm systems
are sized from roof or site area and design rainfall while providing an independent path for overflow when primary drainage
is obstructed. A contractor should select the option that directly controls the identified risk rather than an unrelated
component. Roof drainage components must be coordinated with structural, architectural, and local stormwater
requirements.
Question 4. A sealed basin alternately pressurizes and pulls vacuum as wastewater enters and is
pumped out. What should control these pressure changes?
A. A fuel-gas drip leg
B. A larger water meter
C. A storm overflow
D. A code-compliant basin vent
Correct Answer: D. A code-compliant basin vent
Explanation: A code-compliant basin vent is the best answer because venting allows air to enter and leave the basin so
pumping does not disturb connected trap seals or basin operation. Pumped and special-waste systems must safely handle
discharge characteristics that gravity drainage or ordinary materials cannot accommodate. The other choices address
different system functions and would not resolve the condition described. Basins, pumps, controls, neutralization, and
discharge piping should be selected for the waste type and remain serviceable.
Question 5. A floor-mounted toilet rocks because the connection at the floor is loose and unsupported.
Which component should be checked?
A. The building gas regulator
B. The water-service curb stop
C. The closet flange and anchorage at the fixture outlet
D. The roof-drain overflow
Correct Answer: C. The closet flange and anchorage at the fixture outlet
Explanation: The closet flange and anchorage at the fixture outlet is the best answer because the closet flange provides a
secure mechanical connection and sealing interface between the water closet and drainage piping. Fixtures and connected
appliances must be installed so they are sanitary, serviceable, properly trapped, and supplied with safe water temperatures.
A contractor should select the option that directly controls the identified risk rather than an unrelated component.
Manufacturer instructions and local code govern connection details, clearances, drainage, and required protective devices.
Original practice material • Verify local code edition and amendments Page 2
,SLB Plumbing Contractor Examination — 600 Practice Questions
Question 6. A branch serving many fixtures is extended much farther than originally planned. What
should the contractor verify before installation?
A. That the hot-water thermostat is raised
B. That the gas meter is bypassed
C. That all traps are removed
D. That pipe size and configuration remain adequate for the connected drainage load and code limits
Correct Answer: D. That pipe size and configuration remain adequate for the connected drainage load and
code limits
Explanation: That pipe size and configuration remain adequate for the connected drainage load and code limits is the best
answer because drainage capacity depends on pipe size, slope, configuration, and connected load rather than fixture count
alone. Sanitary drainage systems rely on correct sizing, slope, fittings, cleanouts, and flow direction to transport waste
without leakage or recurring blockage. A contractor should select the option that directly controls the identified risk rather
than an unrelated component. Changes in direction and transitions should use drainage-pattern fittings and remain
accessible where code requires service access.
Question 7. A bid worksheet shows $12,000 labor, $8,000 material, and $2,000 equipment with no other
direct-cost categories. What subtotal should appear before overhead and profit?
A. $24,000
B. $18,000
C. $22,000
D. $20,000
Correct Answer: C. $22,000
Explanation: $22,000 is the best answer because direct cost is the sum of the listed job costs, and $12,000 plus $8,000
plus $2,000 equals $22,000. Accurate takeoffs and sizing depend on reading plans correctly, applying the stated scale, and
using consistent units and formulas. The other responses would leave the primary technical or contractual problem
unresolved. Calculated values should be checked for reasonableness before they are used for procurement or field layout.
Question 8. A plastic water line is routed against a hot flue surface. What is the best corrective action?
A. Increase the water pressure
B. Wrap the flue with paper
C. Relocate or protect the piping to maintain required separation from excessive heat
D. Paint the pipe a lighter color
Correct Answer: C. Relocate or protect the piping to maintain required separation from excessive heat
Explanation: Relocate or protect the piping to maintain required separation from excessive heat is the best answer
because excessive heat can soften or degrade plastic piping and compromise its pressure capability. Material selection and
joining methods must match the piping service, pressure, temperature, listing, and manufacturer requirements. Choosing
among these options requires matching the system function to the actual hazard, load, or field condition. Proper support,
corrosion protection, and joining reduce leaks, premature failure, and inspection problems.
Original practice material • Verify local code edition and amendments Page 3
, SLB Plumbing Contractor Examination — 600 Practice Questions
Question 9. An ice machine drain must be protected from sewage backing directly into the equipment.
What connection concept is appropriate?
A. Discharge indirectly through an approved air gap or air break to a receptor
B. Connect directly below the receptor trap
C. Connect the drain to the gas vent
D. Cap the drain during operation
Correct Answer: A. Discharge indirectly through an approved air gap or air break to a receptor
Explanation: Discharge indirectly through an approved air gap or air break to a receptor is the best answer because
indirect drainage separates sensitive equipment from direct exposure to sewage backup or cross-contamination. Traps
protect occupied spaces from sewer gas, while interceptors and indirect-waste methods keep unsuitable discharges from
impairing the drainage system or contaminating equipment. The remaining options do not provide the protection, control, or
calculation required by the scenario. Trap seals, interceptor access, and air-gap or air-break details must remain
maintainable and code compliant.
Question 10. Why can an air admittance valve not replace every required open vent in a building?
A. Air admittance valves increase water temperature
B. They cause gas appliances to overfire
C. They reduce roof-drain capacity
D. The drainage system still needs code-required open venting to relieve pressure and communicate with
atmosphere
Correct Answer: D. The drainage system still needs code-required open venting to relieve pressure and
communicate with atmosphere
Explanation: The drainage system still needs code-required open venting to relieve pressure and communicate with
atmosphere is the best answer because air admittance valves admit air under vacuum but generally do not relieve positive
pressure or satisfy every open-vent requirement. Venting limits pressure fluctuations in the drainage system so trap seals
are preserved and fixtures drain properly. The other choices address different system functions and would not resolve the
condition described. Vent layout, sizing, termination, and permitted alternative methods depend on the adopted code and
the configuration of the drainage system.
Question 11. A 32-foot drainage run is specified at 1/8 inch per foot. What elevation drop should the
installer lay out?
A. 16 inches
B. 4 inches
C. 8 inches
D. 2 inches
Correct Answer: B. 4 inches
Explanation: 4 inches is the best answer because 32 feet multiplied by 0.125 inch per foot equals 4 inches of total fall.
Accurate takeoffs and sizing depend on reading plans correctly, applying the stated scale, and using consistent units and
formulas. Choosing among these options requires matching the system function to the actual hazard, load, or field
condition. Calculated values should be checked for reasonableness before they are used for procurement or field layout.
Original practice material • Verify local code edition and amendments Page 4
Questions With Answers and Explanations
Question 1. Near substantial completion, remaining minor deficiencies and incomplete items are
documented for correction. What is this list called?
A. A gas manifold schedule
B. A hot-work permit
C. A fixture-unit table
D. A punch list
Correct Answer: D. A punch list
Explanation: A punch list is the best answer because a punch list identifies incomplete or deficient work that must be
corrected before final closeout. Successful plumbing projects combine complete scope review, realistic labor and material
estimates, documented changes, and disciplined schedule control. The other choices address different system functions
and would not resolve the condition described. Clear records and timely communication reduce disputes, rework, and
unplanned cost.
Question 2. A pipe run rises 18 inches over a horizontal distance of 24 feet. What is the average rise per
foot?
A. 1.33 inches per foot
B. 0.25 inch per foot
C. 1.5 inches per foot
D. 0.75 inch per foot
Correct Answer: D. 0.75 inch per foot
Explanation: 0.75 inch per foot is the best answer because 18 inches divided by 24 feet equals 0.75 inch of rise per foot.
Accurate takeoffs and sizing depend on reading plans correctly, applying the stated scale, and using consistent units and
formulas. Choosing among these options requires matching the system function to the actual hazard, load, or field
condition. Calculated values should be checked for reasonableness before they are used for procurement or field layout.
Original practice material • Verify local code edition and amendments Page 1
,SLB Plumbing Contractor Examination — 600 Practice Questions
Question 3. A primary roof drain becomes blocked during a heavy storm. What feature is intended to
limit dangerous ponding?
A. An independent secondary drainage or overflow path
B. A gas sediment trap
C. A larger domestic water meter
D. A sanitary trap primer
Correct Answer: A. An independent secondary drainage or overflow path
Explanation: An independent secondary drainage or overflow path is the best answer because secondary drainage
provides an alternate path when primary drainage is obstructed so roof water does not rise to unsafe levels. Storm systems
are sized from roof or site area and design rainfall while providing an independent path for overflow when primary drainage
is obstructed. A contractor should select the option that directly controls the identified risk rather than an unrelated
component. Roof drainage components must be coordinated with structural, architectural, and local stormwater
requirements.
Question 4. A sealed basin alternately pressurizes and pulls vacuum as wastewater enters and is
pumped out. What should control these pressure changes?
A. A fuel-gas drip leg
B. A larger water meter
C. A storm overflow
D. A code-compliant basin vent
Correct Answer: D. A code-compliant basin vent
Explanation: A code-compliant basin vent is the best answer because venting allows air to enter and leave the basin so
pumping does not disturb connected trap seals or basin operation. Pumped and special-waste systems must safely handle
discharge characteristics that gravity drainage or ordinary materials cannot accommodate. The other choices address
different system functions and would not resolve the condition described. Basins, pumps, controls, neutralization, and
discharge piping should be selected for the waste type and remain serviceable.
Question 5. A floor-mounted toilet rocks because the connection at the floor is loose and unsupported.
Which component should be checked?
A. The building gas regulator
B. The water-service curb stop
C. The closet flange and anchorage at the fixture outlet
D. The roof-drain overflow
Correct Answer: C. The closet flange and anchorage at the fixture outlet
Explanation: The closet flange and anchorage at the fixture outlet is the best answer because the closet flange provides a
secure mechanical connection and sealing interface between the water closet and drainage piping. Fixtures and connected
appliances must be installed so they are sanitary, serviceable, properly trapped, and supplied with safe water temperatures.
A contractor should select the option that directly controls the identified risk rather than an unrelated component.
Manufacturer instructions and local code govern connection details, clearances, drainage, and required protective devices.
Original practice material • Verify local code edition and amendments Page 2
,SLB Plumbing Contractor Examination — 600 Practice Questions
Question 6. A branch serving many fixtures is extended much farther than originally planned. What
should the contractor verify before installation?
A. That the hot-water thermostat is raised
B. That the gas meter is bypassed
C. That all traps are removed
D. That pipe size and configuration remain adequate for the connected drainage load and code limits
Correct Answer: D. That pipe size and configuration remain adequate for the connected drainage load and
code limits
Explanation: That pipe size and configuration remain adequate for the connected drainage load and code limits is the best
answer because drainage capacity depends on pipe size, slope, configuration, and connected load rather than fixture count
alone. Sanitary drainage systems rely on correct sizing, slope, fittings, cleanouts, and flow direction to transport waste
without leakage or recurring blockage. A contractor should select the option that directly controls the identified risk rather
than an unrelated component. Changes in direction and transitions should use drainage-pattern fittings and remain
accessible where code requires service access.
Question 7. A bid worksheet shows $12,000 labor, $8,000 material, and $2,000 equipment with no other
direct-cost categories. What subtotal should appear before overhead and profit?
A. $24,000
B. $18,000
C. $22,000
D. $20,000
Correct Answer: C. $22,000
Explanation: $22,000 is the best answer because direct cost is the sum of the listed job costs, and $12,000 plus $8,000
plus $2,000 equals $22,000. Accurate takeoffs and sizing depend on reading plans correctly, applying the stated scale, and
using consistent units and formulas. The other responses would leave the primary technical or contractual problem
unresolved. Calculated values should be checked for reasonableness before they are used for procurement or field layout.
Question 8. A plastic water line is routed against a hot flue surface. What is the best corrective action?
A. Increase the water pressure
B. Wrap the flue with paper
C. Relocate or protect the piping to maintain required separation from excessive heat
D. Paint the pipe a lighter color
Correct Answer: C. Relocate or protect the piping to maintain required separation from excessive heat
Explanation: Relocate or protect the piping to maintain required separation from excessive heat is the best answer
because excessive heat can soften or degrade plastic piping and compromise its pressure capability. Material selection and
joining methods must match the piping service, pressure, temperature, listing, and manufacturer requirements. Choosing
among these options requires matching the system function to the actual hazard, load, or field condition. Proper support,
corrosion protection, and joining reduce leaks, premature failure, and inspection problems.
Original practice material • Verify local code edition and amendments Page 3
, SLB Plumbing Contractor Examination — 600 Practice Questions
Question 9. An ice machine drain must be protected from sewage backing directly into the equipment.
What connection concept is appropriate?
A. Discharge indirectly through an approved air gap or air break to a receptor
B. Connect directly below the receptor trap
C. Connect the drain to the gas vent
D. Cap the drain during operation
Correct Answer: A. Discharge indirectly through an approved air gap or air break to a receptor
Explanation: Discharge indirectly through an approved air gap or air break to a receptor is the best answer because
indirect drainage separates sensitive equipment from direct exposure to sewage backup or cross-contamination. Traps
protect occupied spaces from sewer gas, while interceptors and indirect-waste methods keep unsuitable discharges from
impairing the drainage system or contaminating equipment. The remaining options do not provide the protection, control, or
calculation required by the scenario. Trap seals, interceptor access, and air-gap or air-break details must remain
maintainable and code compliant.
Question 10. Why can an air admittance valve not replace every required open vent in a building?
A. Air admittance valves increase water temperature
B. They cause gas appliances to overfire
C. They reduce roof-drain capacity
D. The drainage system still needs code-required open venting to relieve pressure and communicate with
atmosphere
Correct Answer: D. The drainage system still needs code-required open venting to relieve pressure and
communicate with atmosphere
Explanation: The drainage system still needs code-required open venting to relieve pressure and communicate with
atmosphere is the best answer because air admittance valves admit air under vacuum but generally do not relieve positive
pressure or satisfy every open-vent requirement. Venting limits pressure fluctuations in the drainage system so trap seals
are preserved and fixtures drain properly. The other choices address different system functions and would not resolve the
condition described. Vent layout, sizing, termination, and permitted alternative methods depend on the adopted code and
the configuration of the drainage system.
Question 11. A 32-foot drainage run is specified at 1/8 inch per foot. What elevation drop should the
installer lay out?
A. 16 inches
B. 4 inches
C. 8 inches
D. 2 inches
Correct Answer: B. 4 inches
Explanation: 4 inches is the best answer because 32 feet multiplied by 0.125 inch per foot equals 4 inches of total fall.
Accurate takeoffs and sizing depend on reading plans correctly, applying the stated scale, and using consistent units and
formulas. Choosing among these options requires matching the system function to the actual hazard, load, or field
condition. Calculated values should be checked for reasonableness before they are used for procurement or field layout.
Original practice material • Verify local code edition and amendments Page 4
