Ontario Building Code Exam: Plumbing - House

According to Ontario Building Code (OBC) Division B, Part 7, what is the minimum required water seal depth for a standard fixture trap?

• A25 mm
• B38 mm
• C50 mm
• D75 mm

Under the OBC, above what temperature must sewage or waste water be cooled before it is discharged into a sanitary drainage system?

• A50°C
• B65°C
• C75°C
• D90°C

Under what condition is Type M copper tubing permitted for use in residential water systems under the OBC?

• AOnly for underground water service lines
• BOnly for above-ground water distribution systems inside a building
• CFor both underground service and above-ground distribution
• DIt is not permitted for potable water systems under any condition

Which of the following standards must ABS plastic pipe and fittings comply with for drainage and venting applications in Ontario?

• ACAN/CSA-B137.5
• BCAN/CSA-B181.1
• CCAN/CSA-B181.2
• DASTM D2564

Under the OBC, solder and fluxes used to join copper pipe in a potable water system must contain no more than what percentage of lead?

• A0.2%
• B0.5%
• C1.0%
• D2.0%

What is the minimum permitted size of a floor drain installed in a residential basement under the OBC?

• A1-1/2 inches (38 mm)
• B2 inches (50 mm)
• C3 inches (75 mm)
• D4 inches (100 mm)

When sheet lead is used for roof flashing around vent terminals in residential construction, what is the minimum required thickness?

• A0.85 mm
• B1.20 mm
• C1.73 mm
• D2.50 mm

Which of the following fixture traps is exempt from the requirement of having a cleanout plug at the bottom of the trap under the OBC?

• AA laundry tub trap
• BA kitchen sink trap
• CA water closet trap
• DA bathtub trap

What is the maximum horizontal spacing permitted for supports of ABS drainage piping in a house?

• A1.0 m
• B1.2 m
• C1.5 m
• D2.0 m

Where are slip joints permitted to be used in the drainage piping system of a house under the OBC?

• AAnywhere in the horizontal drainage system
• BOnly on the inlet side of a trap or in the trap seal
• CIn vertical waste stacks only
• DSlip joints are completely prohibited in residential drainage systems

Which CSA standard applies to PVC plastic pipe and fittings used in residential drainage and venting systems (DWV)?

• ACAN/CSA-B181.1
• BCAN/CSA-B181.2
• CCAN/CSA-B137.3
• DCAN/CSA-B137.5

What is the minimum required size of a cleanout serving a 3-inch drainage pipe?

• A1-1/2 inches
• B2 inches
• C3 inches
• D4 inches

Which of the following is required for all cleanout fittings installed in a house's drainage system?

• AThey must be installed in a vertical position only
• BThey must be constructed of cast iron only
• CThey must be gas-tight and water-tight
• DThey must be located within 1 meter of a window

What is the absolute minimum nominal size permitted for a water service pipe connecting a house to a municipal main or well under the OBC?

• A1/2 inch (15 mm)
• B3/4 inch (20 mm)
• C1 inch (25 mm)
• D1-1/4 inches (32 mm)

What are the two permitted wall thickness classifications for brass pipe used in residential plumbing systems?

• ASchedule 40 and Schedule 80
• BType L and Type M
• CRegular and Extra-Heavy
• DStandard and Double-Strength

Where is galvanized steel pipe prohibited from being used in a residential drainage system under the OBC?

• AAbove ground inside a building
• BUnderground or in a concrete slab
• CWithin 1 meter of a fixture trap
• DAs a vent terminal through the roof

Under the OBC, what type of backwater valve is required in a building sewer serving a dwelling unit to prevent backup from the municipal sewer?

• AA normally closed backwater valve
• BA normally open backwater valve
• CA dual-check backflow preventer
• DA gate valve with manual bypass

Which of the following standards must PEX (cross-linked polyethylene) plastic pipe and fittings comply with for potable water systems?

• ACAN/CSA-B137.1
• BCAN/CSA-B137.5
• CCAN/CSA-B181.1
• DCAN/CSA-B181.2

Which of the following materials is NOT approved for making cleanout plugs in residential DWV systems?

• ABrass
• BPlastic compatible with the pipe
• CLead
• DCopper

What is the maximum horizontal spacing permitted for supports of copper tubing of 1 inch or less in size under the OBC?

• A1.2 m
• B1.8 m
• C2.5 m
• D3.0 m

In a residential potable water system, what is the maximum static pressure permitted in a water distribution system under the OBC?

• A400 kPa (58 psi)
• B550 kPa (80 psi)
• C600 kPa (87 psi)
• D700 kPa (100 psi)

When a pressure-reducing valve or backflow preventer creates a closed system, what must be installed to control thermal expansion under the OBC?

• AA vacuum breaker
• BAn expansion tank or auxiliary relief valve
• CA water hammer arrestor
• DA bypass pipe back to the main

What is the minimum pressure required at any potable water fixture outlet during flow conditions under the OBC?

• A35 kPa (5 psi)
• B50 kPa (7.25 psi)
• C100 kPa (14.5 psi)
• D150 kPa (22 psi)

A water heater temperature and pressure relief valve discharge pipe must terminate not more than how far above the floor or drain?

• A150 mm
• B300 mm
• C450 mm
• D600 mm

Which of the following backflow prevention devices is typically required on residential hose bibbs (exterior faucets) under the OBC?

• AA double check valve assembly (DCVA)
• BA reduced pressure principle backflow preventer (RP)
• CA hose connection vacuum breaker conforming to CSA B64.2
• DAn air gap of at least 50 mm

What is the minimum vertical distance that an atmospheric vacuum breaker (AVB) must be installed above the flood level rim of the fixture it serves?

• A50 mm (2 inches)
• B100 mm (4 inches)
• C150 mm (6 inches)
• D300 mm (12 inches)

Under the OBC, what is the minimum required air gap for a water outlet serving a domestic laundry tray?

• A13 mm
• B25 mm
• C38 mm
• D50 mm

For which hazard level of cross-connection is a Reduced Pressure Principle (RP) backflow preventer required under the OBC?

• AMinor hazard only
• BModerate hazard only
• CSevere hazard only
• DAll hazard levels, regardless of severity

What is the purpose of installing water hammer arrestors in a residential water distribution system?

• ATo prevent hot water from circulating back into the cold water line
• BTo absorb pressure surges caused by rapid closure of valves
• CTo reduce the static water pressure entering the building
• DTo prevent scale buildup inside copper tubing

What is the maximum temperature setting permitted for a water heater temperature relief valve in residential installations?

• A82°C (180°F)
• B90°C (194°F)
• C99°C (210°F)
• D120°C (248°F)

What is the maximum pressure setting permitted for a pressure relief valve installed on a residential water distribution system?

• A550 kPa (80 psi)
• B700 kPa (100 psi)
• C1,034 kPa (150 psi)
• D1,200 kPa (174 psi)

What is the maximum temperature permitted for hot water supplied to a residential bathtub or shower fixture to prevent scalding?

• A43°C (110°F)
• B49°C (120°F)
• C60°C (140°F)
• D70°C (158°F)

What unit of measurement is used under the OBC to calculate the load on a water distribution system for sizing pipes?

• ADrainage Fixture Units (DFU)
• BWater Supply Fixture Units (WSFU)
• CLitres Per Minute (LPM)
• DGallons Per Minute (GPM)

What is the assigned water-supply hydraulic load (water supply fixture units) for a private water closet with a flush tank under the OBC?

• A1.0
• B2.0
• C3.0
• D4.0

Under the OBC, where must a main shut-off valve be installed in a residential water distribution system?

• ADirectly above the hot water tank only
• BAt the kitchen sink sink cabinet only
• COn the water service pipe as close as possible to where it enters the building
• DOnly on the exterior wall of the house

What is the minimum required size of a cold water branch pipe serving a residential tankless water heater?

• A1/2 inch
• B3/4 inch
• C1 inch
• D1-1/4 inches

Why is the use of a gate valve or ball valve preferred over a globe valve as the main shut-off valve in a water service line?

• AThey are cheaper to manufacture
• BThey offer less resistance to flow when fully open
• CThey can be used to regulate pressure
• DThey require less maintenance

What is the minimum required depth of a water service pipe installed underground to prevent freezing in Ontario?

• A0.6 meters
• B1.0 meters
• C1.2 meters or below the local frost line
• D2.5 meters in all locations

Under the OBC, when a water service pipe and a building sewer are installed in the same trench, what is the minimum horizontal separation required?

• ANo separation is required if they are in the same trench
• B300 mm, provided the water service is at least 300 mm above the sewer
• C1.0 m separation must be maintained
• DThey are never allowed in the same trench under any condition

What type of backflow preventer must be installed on a boiler make-up water line in a residential heating system?

• AA simple single check valve
• BA dual check valve backflow preventer with atmospheric port (CSA B64.3)
• CA hose bibb vacuum breaker
• DNo backflow preventer is required for closed-loop boilers

What is the minimum nominal size permitted for a building sewer serving a single-family house under the OBC?

• A2 inches (50 mm)
• B3 inches (75 mm)
• C4 inches (100 mm)
• D6 inches (150 mm)

What is the minimum permitted slope for a horizontal drainage pipe of less than 3 inches in size under the OBC?

• A1 in 25 (4%)
• B1 in 50 (2% or 1/4 inch per foot)
• C1 in 100 (1% or 1/8 inch per foot)
• D1 in 200 (0.5% or 1/16 inch per foot)

What is the minimum permitted slope for a horizontal drainage pipe larger than 3 inches (e.g. a 4-inch building drain) under the OBC?

• A1 in 50 (2%)
• B1 in 100 (1% or 1/8 inch per foot)
• C1 in 150 (0.67%)
• D1 in 200 (0.5%)

What is the drainage hydraulic load in fixture units (DFU) of a water closet with a flush tank under the OBC?

• A1 DFU
• B2 DFU
• C3 DFU
• D4 DFU

What is the Drainage Fixture Unit (DFU) load of a domestic kitchen sink under the OBC?

• A1 DFU
• B2 DFU
• C3 DFU
• D4 DFU

What is the maximum number of Drainage Fixture Units (DFU) that can be connected to a 3-inch horizontal branch under the OBC?

• A6 DFU
• B15 DFU
• C20 DFU
• D36 DFU

What is the maximum distance permitted between cleanouts in a horizontal drainage line of 4 inches or less in size?

• A10 meters
• B15 meters
• C30 meters
• D45 meters