CSLB General Building (B) — All Questions

A temperature-and-pressure (T&P) relief valve on a residential storage water heater must be set to open at a temperature no higher than which value?

• a.210°F✓
• b.180°F
• c.240°F
• d.150°F

A T&P relief valve protects the tank against overheating and must be rated so its temperature element opens at no more than 210°F. The pressure element is a separate rating. Both must be listed and approved for the appliance.2022 California Plumbing Code (CPC) §608.3

The pressure element of a water heater T&P relief valve must be set to open at a pressure not exceeding which value?

• a.100 psi
• b.150 psi✓
• c.200 psi
• d.75 psi

The pressure portion of a listed T&P valve on a domestic water heater is limited to open at no more than 150 psi. This protects the tank, which is typically rated at 150 psi working pressure. Using a higher setting is prohibited.2022 California Plumbing Code (CPC) §608.3

The discharge pipe served by a water heater T&P relief valve must be sized so that it is:

• a.one pipe size smaller than the valve outlet
• b.sized for the water heater inlet
• c.not smaller than the diameter of the valve outlet✓
• d.always 3/4 inch regardless of the valve

The relief discharge pipe must be at least the full size of the T&P valve outlet, with no reduction along its length. Reducing the pipe would restrict flow during a discharge event and defeat the safety function. It must also serve only one relief valve.2022 California Plumbing Code (CPC) §608.5

A T&P relief valve discharge pipe terminating outside the building must end how far above the ground or receptor?

• a.between 24 and 48 inches
• b.flush with the ground
• c.at least 36 inches above grade
• d.not less than 6 inches and not more than 24 inches✓

The end of the discharge pipe must terminate not less than 6 inches and not more than 24 inches above its point of discharge, such as grade or a receptor. This keeps hot water from spraying an occupant while keeping the outlet visible and above flooding. The end must remain unthreaded and point downward.2022 California Plumbing Code (CPC) §608.5

Which condition is required at the terminal end of a water heater relief valve discharge pipe?

• a.It must not be threaded✓
• b.It must have a threaded cap
• c.It must include a shutoff valve
• d.It must contain a trap

The end of a relief discharge line must not be threaded so it cannot be capped or plugged, which would disable the relief path. No valve or trap may be installed in the line. The pipe must drain by gravity and point downward.2022 California Plumbing Code (CPC) §608.5

A plumber is routing the discharge from a water heater T&P valve. Which installation is code-compliant?

• a.Install a ball valve in the line for easy testing
• b.Run the pipe full-size with no valve between the T&P valve and the outlet✓
• c.Reduce the pipe to 1/2 inch to fit through the wall
• d.Trap the line to catch drips before it exits

No shutoff or check valve may be placed between the relief valve and the discharge outlet, because a closed valve would block emergency relief. The pipe stays full-size and untrapped, draining by gravity to an approved point. These rules keep the safety discharge always open.2022 California Plumbing Code (CPC) §608.5

How must a water heater relief valve discharge pipe flow to its point of discharge?

• a.Uphill to an overhead receptor
• b.Level with no slope
• c.Downward, draining by gravity✓
• d.Through a pump to grade

The discharge pipe must run downward from the valve so it drains completely by gravity to the point of discharge. Any low spot, trap, or upward run could hold water and freeze or block the line. Continuous fall keeps the relief path clear.2022 California Plumbing Code (CPC) §608.5

The material used for a water heater T&P relief valve discharge pipe must be:

• a.any flexible plastic tubing on hand
• b.copper only, never plastic
• c.cast iron for durability
• d.rated for the temperature and pressure of the relief discharge✓

The discharge pipe material must be listed and rated to handle the hot water and pressure that a relief event produces. Ordinary low-temperature tubing can soften or fail. Approved materials include those permitted for hot-water distribution, such as CPVC or copper.2022 California Plumbing Code (CPC) §608.5

When a T&P relief discharge terminates to an indoor location such as a floor drain or pan, an air gap is required. Where must that air gap be located?

• a.At the point of discharge, so the pipe does not connect directly to a drain✓
• b.Inside the water heater tank
• c.Only at the water heater cold inlet
• d.At the gas control valve

The relief discharge must terminate through an air gap at the receptor so it is never directly connected to the drainage system. A direct connection could siphon sewer gases or block discharge. The air gap keeps the relief outlet open to atmosphere and visible.2022 California Plumbing Code (CPC) §608.5

Which of the following is prohibited on a water heater relief valve discharge line?

• a.Running it to the outside of the building
• b.Installing a trap in the line✓
• c.Using CPVC rated for hot water
• d.Sizing it full to the valve outlet

A trap must never be installed in a relief discharge line because standing water could freeze or block the emergency path. The line must drain freely by gravity with no valves or traps. It may terminate outside or to an approved receptor with an air gap.2022 California Plumbing Code (CPC) §608.5

California requires storage water heaters to be braced against earthquakes. What is the minimum number of straps required?

• a.One strap at the top
• b.One strap at the center
• c.Two straps, one in the upper third and one in the lower third✓
• d.Four straps evenly spaced

Water heaters must be anchored with at least two straps to resist horizontal displacement in a seismic event. One strap is placed in the upper one-third of the tank and one in the lower one-third. This keeps the tank from toppling and shearing its gas or water connections.2022 California Plumbing Code (CPC) §507.2

When strapping a gas water heater, the lower seismic strap must be located:

• a.directly over the gas control valve
• b.at the very bottom of the tank base
• c.anywhere below the midpoint
• d.at least 4 inches above the controls✓

The lower strap must be positioned no lower than 4 inches above the gas controls so the strap does not interfere with or damage the control valve. The upper strap goes in the upper third of the tank. Both straps anchor the tank to the wall framing.2022 California Plumbing Code (CPC) §507.2

Seismic straps for a water heater must be anchored to what?

• a.The wall studs or structural framing✓
• b.The finished drywall surface only
• c.The flexible gas connector
• d.The relief valve discharge pipe

The straps must be secured into structural framing such as wall studs, not just the drywall, so they can resist the tank's weight during shaking. Anchoring to trim or piping would fail. Proper anchorage keeps water and gas lines intact after a quake.2022 California Plumbing Code (CPC) §507.2

A water heater is being installed in an attic above finished living space. What must be provided to catch leaks?

• a.A floor sink under the joists
• b.A drain pan piped to an approved discharge point✓
• c.Only a leak-alarm sensor
• d.Nothing, since the tank is listed

When a water heater is located where a leak would cause damage, such as an attic over living space, it must sit in a drain pan piped to an approved discharge location. The pan protects the structure below from tank or connection leaks. The drain must run to a point where the leak is visible.2022 California Plumbing Code (CPC) §507.5

A galvanized steel water heater drain pan must be at least what gauge (minimum thickness)?

• a.No. 30 gauge
• b.No. 28 gauge
• c.No. 24 gauge✓
• d.No. 16 gauge

A metallic drain pan of galvanized or aluminum steel must be at least No. 24 gauge. Plastic pans are also permitted at a minimum thickness. The pan must be corrosion resistant to hold water from a leaking tank.

A water heater drain pan must have a minimum depth of:

• a.1/2 inch
• b.3/4 inch
• c.1 inch
• d.1-1/2 inches✓

The pan must be not less than 1-1/2 inches deep so it can hold a reasonable volume before the drain carries water away. A shallower pan would overflow quickly. Depth combined with a proper drain keeps leaks contained and visible.2022 California Plumbing Code (CPC) §507.5

The drain line from a water heater pan must be at least what pipe size?

• a.3/4 inch✓
• b.1/2 inch
• c.1-1/2 inches
• d.2 inches

The pan drain must be piped with a minimum 3/4-inch pipe run by gravity to an approved discharge point. A smaller line could clog or fail to carry the leak. The drain must be independent and terminate where the discharge is readily observed.2022 California Plumbing Code (CPC) §507.5

Where should a water heater pan drain terminate?

• a.Into the tank's own T&P line
• b.At an approved location where the discharge is readily observed✓
• c.Into a sealed, hidden cavity
• d.Back into the cold water supply

The pan drain must discharge to an approved point where a leak will be readily seen, alerting the owner to a problem. It cannot combine with the T&P discharge in a way that hides either flow. Visibility is the purpose of both the pan and its drain.2022 California Plumbing Code (CPC) §507.5

A house has a water meter with a check valve installed on the service. What must be added at the water heater to control thermal expansion?

• a.A second T&P valve
• b.A larger cold water pipe
• c.An expansion tank or approved expansion control device✓
• d.A pressure-reducing valve on the hot side

When a check valve, backflow preventer, or pressure-reducing valve creates a closed system, heated water cannot expand back into the main and pressure spikes. An expansion tank or listed expansion control device must be installed to absorb that thermal expansion. Without it, the relief valve may weep or the tank may be stressed.2022 California Plumbing Code (CPC) §608.3

Thermal expansion in a domestic hot water system is primarily caused by:

• a.water hammer from fast-closing valves
• b.air trapped in the piping
• c.corrosion inside the tank
• d.water increasing in volume as it is heated✓

Water expands in volume as it is heated, and in a closed system that added volume has nowhere to go, raising system pressure. This is thermal expansion. An expansion tank absorbs the increase to protect fixtures, the tank, and the relief valve.2022 California Plumbing Code (CPC) §608.3

A gas water heater is installed in a residential garage. To reduce the risk of igniting flammable vapors, the ignition source should generally be elevated above the floor by at least:

• a.18 inches✓
• b.6 inches
• c.12 inches
• d.30 inches

Gasoline and other heavy flammable vapors tend to settle near the floor of a garage. Elevating the ignition source, such as a pilot or burner, at least 18 inches above the floor reduces the chance of ignition. Listed flammable-vapor-ignition-resistant (FVIR) heaters may change the specifics, but the 18-inch elevation is the traditional rule.

A fuel-gas water heater installed in a small closet requires combustion air primarily to:

• a.cool the discharge pipe
• b.supply oxygen for safe, complete combustion and proper venting✓
• c.increase the water temperature
• d.pressurize the expansion tank

A gas burner needs adequate combustion air so fuel burns completely and does not produce dangerous carbon monoxide. Insufficient air also causes poor draft and backdrafting of flue gases. Confined spaces must be provided with openings or ducts sized for the appliance input.

An atmospherically vented gas water heater relies on which principle to move flue gases out of the building?

• a.A powered blower on the tank
• b.Positive pressure from the gas supply
• c.The natural buoyancy of hot flue gases rising through the vent (draft)✓
• d.The T&P relief valve

A natural-draft (atmospheric) water heater vents by the buoyancy of hot combustion gases rising through a properly sized and sloped vent connector and flue. Adequate draft depends on vent height, slope, and combustion air. Blockage or poor connector slope can cause dangerous spillage of flue gases.

Under current California requirements, a new residential water closet may use a maximum flush volume of:

• a.3.5 gallons per flush
• b.2.2 gallons per flush
• c.1.6 gallons per flush
• d.1.28 gallons per flush✓

New water closets in California are limited to a maximum of 1.28 gallons per flush, a high-efficiency standard also reflected in CALGreen. Older 1.6-gpf and 3.5-gpf models are no longer compliant for new installations. The lower flush volume conserves water while still clearing the bowl.2022 California Plumbing Code (CPC) §411.2

The maximum flush volume allowed for a new urinal (other than wall-mounted) in California is generally:

• a.0.5 gallon per flush✓
• b.1.0 gallon per flush
• c.1.6 gallons per flush
• d.2.0 gallons per flush

New urinals are limited to a maximum of 0.5 gallon per flush, with high-efficiency and non-water urinals using far less. This reflects both plumbing code and CALGreen water-efficiency goals. Choosing a compliant urinal is required for new commercial restrooms.2022 California Plumbing Code (CPC) §412.2

The federal WaterSense label on a plumbing fixture indicates that the fixture:

• a.is made only of recycled brass
• b.meets water-efficiency and performance criteria✓
• c.requires no vent connection
• d.is exempt from local permits

WaterSense is an EPA program that labels fixtures meeting both water-efficiency and performance standards. A WaterSense toilet, for example, uses no more than 1.28 gpf while still flushing effectively. The label helps identify products that satisfy CALGreen efficiency goals.

A water closet must have a minimum clearance from the center of the bowl to the nearest side wall or partition of:

• a.10 inches
• b.12 inches
• c.15 inches✓
• d.21 inches

The centerline of a water closet must be at least 15 inches from any side wall or partition. This provides room to use the fixture and to service it. Adjacent fixtures require additional center-to-center spacing.2022 California Plumbing Code (CPC) §402.5

The minimum clearance required in front of a water closet, measured from the front of the bowl to any wall or fixture, is:

• a.12 inches
• b.15 inches
• c.18 inches
• d.24 inches✓

A clear space of at least 24 inches must be provided in front of a water closet or urinal. This clearance allows a person to approach and use the fixture. It is measured from the front of the fixture to the nearest obstruction.2022 California Plumbing Code (CPC) §402.5

Two water closets set side by side in a public restroom must have a minimum center-to-center spacing of:

• a.30 inches✓
• b.24 inches
• c.21 inches
• d.15 inches

Adjacent water closets must be spaced at least 30 inches center-to-center. This equals the 15-inch minimum from each centerline to a common point. Proper spacing gives each fixture room for use and cleaning.2022 California Plumbing Code (CPC) §402.5

Under CALGreen residential requirements, a lavatory (bathroom) faucet is generally limited to a maximum flow rate of about:

• a.2.2 gpm at 60 psi
• b.1.2 gpm at 60 psi✓
• c.2.5 gpm at 80 psi
• d.0.35 gpm at 60 psi

CALGreen limits residential lavatory faucets to a maximum of about 1.2 gallons per minute at 60 psi. This is stricter than older 2.2-gpm faucets. The reduced flow conserves water at hand-washing fixtures.2022 CALGreen §4.303.1

Under CALGreen, a residential showerhead is generally limited to a maximum flow rate of:

• a.2.5 gpm at 80 psi
• b.2.2 gpm at 60 psi
• c.1.8 gpm at 80 psi✓
• d.0.5 gpm at 60 psi

CALGreen limits residential showerheads to a maximum of 1.8 gallons per minute at 80 psi. Where multiple showerheads serve one shower, their combined flow generally cannot exceed the limit. This conserves both water and the energy to heat it.2022 CALGreen §4.303.1

Which statement about traps on plumbing fixtures is correct?

• a.Two fixtures may never share any drain
• b.A fixture needs a trap only if it drains hot water
• c.Traps are optional on floor drains
• d.Each plumbing fixture must be separately trapped, with limited exceptions✓

Each plumbing fixture generally must be individually trapped to keep sewer gases out of the building. Limited exceptions allow, for example, a three-compartment sink to share a trap under specific rules. The trap's water seal is the barrier against gases.2022 California Plumbing Code (CPC) §1002.1

A standard fixture trap must maintain a liquid seal of not less than 2 inches and not more than:

• a.4 inches✓
• b.3 inches
• c.6 inches
• d.8 inches

A trap seal must be between 2 and 4 inches deep unless a deep-seal trap is required by other provisions. Too shallow a seal is easily broken by siphonage; too deep can retain solids. The 2-to-4-inch range balances protection and self-cleaning.2022 California Plumbing Code (CPC) §1002.1

When setting a floor-mounted water closet, the connection to the closet flange must be made:

• a.with plumber's putty only
• b.watertight and gastight, typically with a wax ring or approved gasket✓
• c.using silicone caulk around the base as the only seal
• d.by threading the bowl directly onto the drain

The water closet must seal to the closet flange with a wax ring or listed gasket so the joint is both watertight and gastight. The bowl is then bolted down evenly to the flange. A poor seal leaks water and lets sewer gas escape at the floor.

A properly installed closet flange should sit at what position relative to the finished floor?

• a.at least 1 inch below the finished floor
• b.flush only when the floor is tile
• c.on top of, or flush with, the finished floor✓
• d.recessed 2 inches into the subfloor

The closet flange should rest on top of the finished floor so the water closet can seal correctly with the wax ring. A flange set too low leaves a gap the wax cannot bridge, causing leaks. Extension rings are used when flooring raises the floor level.

What is the primary purpose of the wax ring used when setting a water closet?

• a.to level the bowl on an uneven floor
• b.to anchor the bowl to the studs
• c.to reduce flush noise
• d.to form a watertight, gastight seal between the bowl and the flange✓

The wax ring compresses between the water closet horn and the flange to create a seal that stops water leaks and sewer gas. It is not a structural or leveling component. Bolts and shims handle alignment; the wax handles the seal.

An accessible (ADA/CBC) water closet must have the top of the seat at what height above the finished floor?

• a.17 to 19 inches✓
• b.10 to 12 inches
• c.20 to 24 inches
• d.24 to 28 inches

For an accessible water closet, the top of the seat must be 17 to 19 inches above the finished floor. This range lets a person transfer from a wheelchair. Standard (non-accessible) toilets are typically lower.

An accessible lavatory must provide knee and toe clearance underneath. The minimum height of the knee clearance space at the front edge is typically:

• a.24 inches
• b.27 inches✓
• c.34 inches
• d.40 inches

An accessible lavatory generally requires about 27 inches of clear knee height at the front edge, with the rim mounted no higher than 34 inches. Exposed hot water and drain piping beneath must be insulated or otherwise protected. These clearances let a wheelchair user roll under the fixture.

Grab bars at an accessible water closet must be designed to resist a minimum applied load of:

• a.100 pounds
• b.150 pounds
• c.250 pounds✓
• d.500 pounds

Grab bars and their fasteners and wall backing must be able to withstand at least a 250-pound point load in any direction. This ensures the bar supports a person safely. Adequate blocking must be installed in the wall to carry the load.

The minimum number of plumbing fixtures required for a building is determined primarily by:

• a.the color of the fixtures
• b.the water heater capacity
• c.the length of the water service
• d.the building's occupancy classification and occupant load✓

The minimum required plumbing fixtures are set by the occupancy type and the number of occupants, typically from a code table. This determines required water closets, lavatories, and other fixtures for each sex. Undersizing fixture counts is a common plan-check rejection.2022 California Plumbing Code (CPC) §422.1

A shower or tub-shower valve in a residence must be an approved anti-scald type that limits hot water temperature to a maximum of:

• a.120°F✓
• b.140°F
• c.160°F
• d.180°F

Individual shower and tub-shower control valves must be pressure-balancing or thermostatic anti-scald types limited to a maximum of 120°F at the outlet. This protects users from sudden temperature spikes and burns. The valve limit stop is set during installation.

A pressure-balancing shower valve protects a bather primarily by:

• a.shutting off water if the drain clogs
• b.maintaining outlet temperature when cold or hot supply pressure changes✓
• c.increasing flow to 3 gpm automatically
• d.venting the shower drain

A pressure-balancing valve senses changes in hot or cold supply pressure, such as a flushed toilet stealing cold water, and adjusts to keep the outlet temperature stable. This prevents a sudden scald or cold shock. It is one approved anti-scald method along with thermostatic valves.

The minimum required air gap between a fixture's water supply outlet and the fixture's flood-level rim protects against:

• a.water hammer
• b.thermal expansion
• c.backflow of contaminated water into the potable supply✓
• d.scalding

An air gap is a vertical space between the supply outlet and the flood-level rim of a fixture that prevents contaminated water from being siphoned back into the potable system. It is the most reliable backflow protection. The minimum gap depends on the outlet size and nearby walls.2022 California Plumbing Code (CPC) §603.3.1

A lavatory or sink is required to have an overflow only when:

• a.it is made of stainless steel
• b.it serves a commercial kitchen
• c.it is set on a pedestal
• d.the fixture design includes one; where provided, it must connect on the fixture side of the trap✓

Not every fixture must have an overflow, but where a fixture is furnished with one, the overflow passage must connect to the fixture side of the trap so its water is renewed and sealed. An overflow that connects on the sewer side would bypass the trap seal. The overflow must be designed so it cannot cause cross-contamination.

Plumbing fixtures must be constructed of materials that are:

• a.smooth, impervious, and free of concealed fouling surfaces✓
• b.porous to allow drying
• c.always cast iron
• d.rough-textured for grip

Fixtures must have smooth, impervious, nonabsorbent surfaces without concealed fouling areas so they stay sanitary and cleanable. Porous or rough surfaces would harbor bacteria and stains. This applies to the fixture body and its exposed surfaces.2022 California Plumbing Code (CPC) §402.1

A wall-hung urinal in a standard adult commercial restroom is typically set with the lip of the fixture at a maximum height above the floor of about:

• a.30 inches
• b.24 inches✓
• c.36 inches
• d.40 inches

For standard (non-child) use, a wall-hung urinal lip is commonly set no higher than about 24 inches above the finished floor. Accessible urinals must have the rim no higher than 17 inches. Manufacturer rough-in dimensions and accessibility rules govern the exact setting height.

Compared with a two-piece water closet, a one-piece (integral tank and bowl) water closet generally offers which advantage?

• a.a larger flush volume
• b.no need for a wax ring
• c.fewer joints and a lower profile with easier cleaning✓
• d.elimination of the trap

A one-piece water closet integrates the tank and bowl, so there are fewer joints to leak and a lower, smoother profile that is easier to clean. It still requires a wax ring seal to the flange and a trap. The choice is largely about maintenance and appearance.

A residential dishwasher discharge must be protected against backflow. Which method is an approved way to do this?

• a.connect the drain hose to the floor
• b.run the hose in a straight downhill line
• c.install a check valve only
• d.an approved dishwasher air gap fitting, or a high loop where permitted✓

A dishwasher drain must have an air gap to prevent waste water from siphoning back into the machine. An approved air-gap fitting mounted at the counter is the standard method; a high loop is accepted in some jurisdictions. A simple check valve alone is not adequate backflow protection.2022 California Plumbing Code (CPC) §807.3

A water heater's T&P relief valve must be installed so that it is:

• a.accessible for inspection, testing, and replacement✓
• b.concealed inside the wall
• c.located below the tank base
• d.sealed permanently to prevent tampering

The relief valve must remain accessible so it can be inspected, manually tested, and replaced when needed. Concealing or sealing it would prevent required maintenance. Its sensing element must reach into the top of the tank where water is hottest.2022 California Plumbing Code (CPC) §608.3

Which of the following is prohibited between a water heater and its T&P relief valve?

• a.a listed dielectric fitting
• b.any shutoff or check valve✓
• c.a temperature sensor well
• d.the tank tapping itself

No shutoff, check valve, or other valve may be installed between the tank and the T&P relief valve, because it could isolate the valve and defeat over-pressure protection. The relief valve must sense tank conditions directly. Only approved fittings that do not restrict operation are allowed.2022 California Plumbing Code (CPC) §608.3

A water heater must be installed so that:

• a.it is fully enclosed with no access
• b.the burner faces a combustible wall
• c.it is accessible for inspection, service, and replacement✓
• d.the controls are hidden behind drywall

Water heaters must be located and installed with adequate access and clearances for inspection, servicing, and replacement. Enclosing the appliance without access violates the code and manufacturer listing. Required working space keeps the unit serviceable and safe.2022 California Plumbing Code (CPC) §507.0

The temperature-sensing element of a water heater T&P relief valve must be located so that it senses:

• a.the incoming cold water
• b.the room air temperature
• c.the flue gas temperature
• d.the water in the top 6 inches of the tank✓

The T&P valve's temperature element must extend into the top 6 inches of the tank, where the water is hottest, so it responds to dangerous overheating. Sensing cooler water lower in the tank would delay relief. Correct placement is essential to the valve's protective function.2022 California Plumbing Code (CPC) §608.3

A thermal expansion tank installed on a water heater system must be:

• a.supported so its weight is not carried by the connecting piping✓
• b.filled completely with water
• c.installed only on the hot outlet
• d.left unpressurized

An expansion tank, especially when full of water, is heavy and must be independently supported so its weight does not stress or break the piping. The air side is precharged to match system pressure. Proper support and precharge let the tank absorb thermal expansion reliably.

Water hammer arrestors are installed on a water distribution system primarily to:

• a.prevent backflow
• b.absorb the shock of quick-closing valves and reduce pipe noise and damage✓
• c.raise system pressure
• d.filter sediment

Quick-closing valves, such as those on clothes washers and dishwashers, cause a pressure surge (water hammer) that bangs pipes and can loosen joints. Water hammer arrestors provide a cushion of air or a piston to absorb that shock. They are installed near the quick-closing valve they protect.2022 California Plumbing Code (CPC) §609.10

An outdoor hose bibb (sillcock) must be protected against backflow by:

• a.an expansion tank
• b.a pressure-reducing valve
• c.an atmospheric or listed hose-connection vacuum breaker✓
• d.a check valve on the water heater

A hose bibb can create a cross-connection when a hose is submerged in contaminated water, so it must have a hose-connection vacuum breaker (or be a listed anti-siphon type). This device admits air to break any back-siphonage. It protects the potable supply from garden or utility contaminants.2022 California Plumbing Code (CPC) §603.5.7

Each fixture supply to a lavatory or water closet is commonly fitted with an angle stop primarily to:

• a.prevent backflow
• b.arrest water hammer
• c.reduce the flow rate
• d.allow the fixture to be shut off individually for service✓

An angle stop (fixture shutoff valve) lets a single fixture be isolated for repair or replacement without shutting off water to the whole building. It is installed on the supply riser to the fixture. This is a convenience and service requirement, not a backflow or flow-control device.

A water heater installed in an attic must be reached by a passageway and working platform. A typical minimum requirement is a solid, continuous passageway not less than:

• a.30 inches wide with a level working platform at the appliance✓
• b.12 inches wide
• c.48 inches wide with stairs
• d.6 inches wide

Attic-installed water heaters generally require a solid passageway at least 30 inches wide from the access opening to the appliance, plus a level working platform in front of the service side. A light and receptacle are also commonly required. These provisions let the unit be serviced safely.

Cross-connection control in a potable water system is intended to:

• a.increase water pressure at fixtures
• b.prevent nonpotable or contaminated water from entering the potable supply✓
• c.reduce pipe corrosion
• d.silence water hammer

Cross-connection control uses air gaps and backflow prevention devices to keep contaminated or nonpotable water from flowing back into the drinking water system. Backflow can occur by back-siphonage or back-pressure. Protecting every actual or potential cross-connection is a core plumbing safety requirement.2022 California Plumbing Code (CPC) §603.2

A floor drain located in a room that is used infrequently may lose its trap seal by evaporation. The approved way to keep the seal is to provide:

• a.a larger trap arm
• b.a second floor drain nearby
• c.a trap primer or an approved trap seal protection device✓
• d.a deeper cleanout

In little-used areas, water in a floor drain trap can evaporate and let sewer gas enter. A trap primer periodically adds water to maintain the seal, or an approved barrier-type trap seal device may be used. This keeps the required 2-to-4-inch seal intact.

A plumber replaces a water heater in a finished basement over a slab where a leak would not damage anything below, but the local code still requires spill protection. If a drain pan is installed, its drain must:

• a.connect directly into the sanitary sewer without an air gap
• b.loop upward before discharging
• c.be capped until a leak occurs
• d.discharge by gravity to an approved location where it will be readily observed✓

When a drain pan is installed, its drain line must run by gravity to an approved discharge point where a leak becomes readily visible, so the problem is noticed early. It must not tie directly into the sanitary drainage system without proper separation. Visibility of the discharge is the key requirement.2022 California Plumbing Code (CPC) §507.5