Journeyman Plumber (UPC/IPC) — All Questions

A sizing problem leaves 26 psi available for friction. The measured developed length to the most remote fixture is 160 ft and fittings are estimated to add 50 percent. What is the allowable friction loss per 100 ft of pipe?

• a.26 psi per 100 ft
• b.6.5 psi per 100 ft
• c.16.3 psi per 100 ft
• d.10.8 psi per 100 ft✓

Total equivalent length is 160 x 1.5 = 240 ft, so 26 / 240 x 100 = 10.8 psi per 100 ft. 16.3 uses only the measured 160 ft, 6.5 overstates the equivalent length, and 26 skips the division by length.

A dwelling has one flush-tank water closet (2.5 WSFU), one bathtub with shower (2.0 WSFU), one lavatory (1.0 WSFU), one kitchen sink (1.5 WSFU), and one clothes washer (4.0 WSFU). What is the total water supply fixture unit load?

• a.12.5 WSFU
• b.10.0 WSFU
• c.11.0 WSFU✓
• d.9.0 WSFU

Adding the listed values: 2.5 + 2.0 + 1.0 + 1.5 + 4.0 = 11.0 WSFU. 9.0 and 10.0 drop a fixture, and 12.5 adds load not in the list. The total is then read against the sizing table.

Using velocity (fps) = 0.408 x flow (gpm) / inside diameter squared (in), what is the velocity of 8 gpm in 1/2 in Type L copper with an inside diameter of 0.545 in?

• a.6.0 fps
• b.5.5 fps
• c.8.0 fps
• d.11.0 fps✓

0.408 x 8 = 3.264, and 0.545 squared is 0.297, so 3.264 / 0.297 = 11.0 fps, well above the practical 8 fps cold-water limit, which shows 1/2 in is too small for 8 gpm. The lower answers divide by the diameter rather than its square.

The highest fixture is 35 ft above the meter and needs 15 psi residual, meter loss is 6 psi, and friction loss is 14 psi. What minimum static pressure is needed at the meter?

• a.35.0 psi
• b.50.2 psi✓
• c.44.0 psi
• d.29.0 psi

Add every loss to the residual: 35 x 0.433 = 15.2 psi elevation, plus 6 meter, plus 14 friction, plus 15 residual = 50.2 psi. 35.0 omits the elevation loss and 44.0 understates it.

An 80 ft straight run of CPVC will see a 80 degree F temperature change. Using a thermal-expansion coefficient of 0.000034 in per in per degree F, about how much will it move?

• a.1.3 in
• b.3.9 in
• c.0.9 in
• d.2.6 in✓

Convert to inches: 80 ft = 960 in, and 960 x 0.000034 x 80 = 2.6 in, so an offset or expansion loop is needed. 1.3 in halves the movement and 3.9 in overstates the temperature change.

Under IPC Table 604.3, what minimum flow pressure is required at a flushometer-valve water closet?

• a.8 psi
• b.25 psi✓
• c.35 psi
• d.15 psi

A flushometer-valve water closet requires about 25 psi minimum flow pressure to operate the valve (IPC Table 604.3), far more than a tank fixture. 8 psi is the lavatory requirement, and 15 psi and 35 psi are not the tabulated value for this fixture.

Under IPC Table 604.3, what minimum flow pressure is required at a lavatory faucet?

• a.15 psi
• b.8 psi✓
• c.20 psi
• d.4 psi

A lavatory faucet requires a minimum flow pressure of about 8 psi (IPC Table 604.3). 4 psi is below the tabulated value, and 15 psi and 20 psi are higher than a lavatory needs (closer to flushometer requirements).

A chemical feed connection to the potable supply is a high-hazard (health) cross-connection subject to back-pressure under continuous pressure. Which device is required?

• a.A reduced pressure principle assembly✓
• b.A double check valve assembly
• c.A pressure vacuum breaker
• d.An atmospheric vacuum breaker on the branch

A high-hazard connection with back-pressure under continuous pressure requires a reduced pressure principle assembly (IPC 608.13.2). A double check is only for low hazard, and vacuum breakers protect against back-siphonage, not back-pressure.

An atmospheric vacuum breaker (AVB) may NOT have which of the following?

• a.A fixture or outlet located below it on the same branch that it protects against back-siphonage
• b.Copper piping upstream
• c.A hose thread outlet
• d.Any valve downstream of it, and it may not be under continuous pressure for more than 12 hours✓

An AVB relies on atmospheric venting, so no shutoff valve may be located downstream of it and it may not be under continuous pressure for more than 12 hours (IPC 608.13.6). Upstream piping material and a downstream fixture do not disqualify it.

How does a pressure vacuum breaker (PVB) differ from an atmospheric vacuum breaker?

• a.It needs no minimum installation height
• b.It protects against both back-pressure and back-siphonage, so it may be used on any cross-connection regardless of the hazard level involved
• c.It is for back-pressure only
• d.It may be installed under continuous pressure and has test cocks and a spring-loaded check, but protects only against back-siphonage✓

A PVB has a spring-loaded air inlet and check plus test cocks, so it may stay under continuous pressure and can be tested, unlike an AVB. It still protects only against back-siphonage, not back-pressure, and must be at least 12 in above the highest downstream outlet.

Which material is NOT approved for hot-water distribution piping?

• a.PEX
• b.CPVC
• c.Type L copper
• d.PVC✓

PVC is rated for cold-water and DWV service only and will soften and fail on hot water; CPVC is the chlorinated version made for hot water. Type L copper and PEX are both approved for hot-water distribution.

Before a new potable water line is placed in service, it must be:

• a.Left as installed
• b.Filled with hot water
• c.Pressure tested with air only, then placed directly in service
• d.Disinfected (chlorinated) and flushed✓

New potable water piping must be disinfected with a chlorine solution and then flushed before use to remove contamination introduced during installation (IPC 610.1). A pressure test alone does not sanitize the pipe.

What must be provided on the water service near where it enters the building?

• a.Only a pressure-reducing valve, with no separate shutoff on the service
• b.Only a check valve
• c.No valve at all
• d.An accessible main shutoff valve on the water service✓

A full-open, accessible main shutoff valve is required on the water service so the whole building supply can be isolated (IPC 606.1). A check valve or a pressure-reducing valve serves a different purpose and does not satisfy the main-shutoff requirement.

What does the code require at each individual fixture supply?

• a.A check valve at each fixture
• b.A single shutoff valve at the main, which serves all of the fixtures at once
• c.An accessible shutoff (stop) valve on each fixture supply✓
• d.No shutoffs at fixtures

Each fixture supply must have an accessible individual stop valve so the fixture can be serviced without shutting down the whole building (IPC 606.2 lists where stops are required). A single main shutoff does not meet the individual-fixture requirement.

Why are listed mechanical water-hammer arrestors preferred over plain air chambers?

• a.Air chambers are illegal
• b.There is no difference
• c.Air chambers are cheaper
• d.Plain air chambers waterlog and lose their air cushion over time, while listed arrestors keep their charge✓

A capped-pipe air chamber gradually absorbs its air into the water and waterlogs, losing its cushion, whereas a listed mechanical arrestor keeps a sealed air or gas charge. That reliability is why arrestors are specified for quick-closing valves.

In water-service sizing, how is the pressure lost through the water meter handled?

• a.Ignored
• b.Relevant only for wells
• c.Subtracted from the available pressure before sizing the piping✓
• d.Added to the available pressure, since the meter is said to boost downstream flow

Meter pressure loss at design flow is one of the deductions taken from the static supply pressure, along with elevation, residual, and backflow-device losses, before the remainder is left for pipe friction. Ignoring it oversizes the friction budget and undersizes the pipe.

For water-distribution sizing, the developed length is measured:

• a.Along the actual pipe run to the most remote fixture✓
• b.To the nearest fixture
• c.As only the vertical rise
• d.As the straight-line (as-the-crow-flies) distance to the most remote fixture

Developed length is measured along the centerline of the pipe, following every offset, to the most hydraulically remote fixture, since that path governs friction loss. A straight-line or nearest-fixture measurement understates the run.

What is the generally accepted maximum design velocity for a cold-water distribution line?

• a.5 fps
• b.12 fps
• c.8 fps✓
• d.15 fps

Cold-water lines are commonly designed to a maximum of about 8 fps to limit noise and erosion; hot-water lines are held lower, near 5 fps. 12 fps and 15 fps are well above accepted practice and cause velocity noise and pipe wear.

A common method of disinfecting new potable piping uses a chlorine concentration and contact time of about:

• a.5 ppm for 1 hour
• b.No minimum concentration is specified; a simple flush with clean water is enough
• c.50 ppm held about 24 hours (or 200 ppm for about 3 hours)✓
• d.500 ppm for 10 minutes

A typical disinfection procedure charges the system to at least 50 ppm chlorine for about 24 hours, or a stronger 200 ppm for about 3 hours, then flushes and confirms an acceptable residual (IPC 610.1). A brief 5 ppm dose is too weak and short.

What is the minimum supply pipe size for a hose bibb (sillcock)?

• a.1 in
• b.3/8 in
• c.1/4 in
• d.1/2 in✓

A hose bibb requires a minimum 1/2 in supply (IPC Table 604.5). 1/4 in and 3/8 in are undersized, and 1 in is far larger than a single sillcock needs.

A water-distribution system is tested with water at not less than its working pressure. For how long must the pressure hold with no drop?

• a.15 minutes✓
• b.1 hour
• c.5 minutes
• d.10 minutes

The water-supply test holds at not less than the working pressure for at least 15 minutes with no loss of pressure (IPC 312.5). Any drop indicates a leak; 5 or 10 minutes is short of the required duration.

A lawn irrigation system injects fertilizer or chemicals into the water. What backflow protection does this high-hazard connection require?

• a.A double check valve assembly on the irrigation branch
• b.A reduced pressure principle assembly✓
• c.An atmospheric vacuum breaker
• d.A pressure vacuum breaker

Chemical injection makes irrigation a high-hazard (health) connection, and where it is under continuous pressure or subject to back-pressure it requires a reduced pressure principle assembly (IPC 608.13.2). A vacuum breaker or double check does not protect a high-hazard, back-pressure connection.

Which materials are commonly used for an underground water service?

• a.CPVC only
• b.Type M copper only
• c.Type K copper or PE plastic✓
• d.Galvanized steel pipe only, because it resists corrosion in soil

Underground water services are commonly Type K copper (the heaviest wall) or polyethylene (PE) plastic, both suited to burial (IPC 605 / UPC 604). Type M is generally restricted to above-ground use, and galvanized steel corrodes in soil.

Which provides the most positive, reliable backflow protection for a cross-connection?

• a.An atmospheric vacuum breaker
• b.A pressure vacuum breaker
• c.An air gap (a physical separation)✓
• d.A double check valve assembly

An air gap is a physical vertical separation of at least twice the supply-opening diameter and cannot fail mechanically, so it is the most reliable backflow protection (IPC 608.15.1). Mechanical assemblies rely on checks and springs that can wear.

Where must a lavatory faucet spout be located relative to the flood level rim of the basin?

• a.At the flood level rim
• b.Below the flood level rim
• c.Above the flood level rim to maintain an air gap✓
• d.Submerged in the basin

The faucet spout must terminate above the flood level rim of the fixture so that if the basin fills and the supply loses pressure, contaminated water cannot be siphoned back through the spout (IPC 608.15.1). A spout at or below the rim creates a submerged-inlet cross-connection.

A flushometer valve must be provided with what backflow protection?

• a.An air gap only
• b.An integral (built-in) vacuum breaker✓
• c.A check valve only
• d.No backflow protection

A flushometer discharges below the rim of the fixture, so it must have an integral vacuum breaker downstream of the valve to prevent back-siphonage of fixture water into the supply (IPC 608.15.4). A plain check valve does not provide this protection.

A storage water heater's combination temperature and pressure relief valve is typically rated to open at about:

• a.210 degrees F / 150 psi✓
• b.180 degrees F / 75 psi
• c.250 degrees F / 300 psi
• d.140 degrees F / 50 psi

A standard residential T and P relief valve is rated to relieve at 210 degrees F and 150 psi, protecting the tank from both overheating and overpressure (IPC 504.4). The other settings do not match the listed valve ratings.

The discharge pipe from a water heater's temperature and pressure relief valve must be:

• a.Fitted with a service shutoff valve
• b.Directed upward
• c.The full size of the valve outlet, draining by gravity, with no valve in the line✓
• d.Reduced to 1/2 in copper for a neater appearance and terminated well above the floor

The T and P discharge pipe must be full size of the valve outlet, drain by gravity, contain no valves, and terminate 6 to 24 in above an approved location with no threads on the end (IPC 504.6). Reducing it, valving it, or running it upward is prohibited.

A storage water heater must be equipped with:

• a.No drain valve
• b.A check valve on the outlet
• c.A drain valve at its lowest point✓
• d.Only a vacuum relief valve

A storage water heater must have a drain valve at its lowest point so the tank can be flushed and drained for service (IPC 504.3). A vacuum relief valve is required only on bottom-fed tanks and does not replace the drain.

A 100,000 Btu/h water heater draws combustion air from outdoors through two horizontal ducts. Using 1 square inch per 2,000 Btu/h for horizontal ducts, what free area must each opening have?

• a.100 square inches
• b.25 square inches
• c.50 square inches✓
• d.12-1/2 square inches

100,000 / 2,000 = 50 square inches for each of the two openings. The vertical-duct method uses 1 square inch per 4,000 Btu/h; using that gives 25, which understates the horizontal-duct requirement.

Using the single-opening (one permanent opening) method that communicates directly with the outdoors at 1 square inch per 1,000 Btu/h, what free area is required for a 120,000 Btu/h appliance?

• a.60 square inches
• b.30 square inches
• c.120 square inches✓
• d.240 square inches

120,000 / 1,000 = 120 square inches, and the single opening must also be at least the sum of the appliance connectors (minimum 100 square inches typically). 30 and 60 apply the 4,000 or 2,000 ratios used for two-opening methods.

A listed flammable-vapor-ignition-resistant (FVIR) gas water heater is installed in a residential garage. What does its listing allow?

• a.It must still be elevated 18 in in all cases
• b.It may be installed at floor level, because it resists igniting flammable vapors✓
• c.It requires no venting
• d.It is prohibited in garages

An FVIR water heater has a flame-arrestor design listed to resist igniting flammable vapors, so it may be installed at floor level in a garage where an ordinary heater would need its ignition source 18 in above the floor. It still must be vented normally.

A single-wall metal vent connector on a gas water heater must maintain what minimum clearance to combustible material?

• a.18 in
• b.6 in✓
• c.12 in
• d.1 in

A single-wall metal vent connector must be kept at least 6 in from combustibles (IFGC / NFPA 54). 1 in is unsafe, and 12 in or 18 in is more clearance than the connector requires (double-wall connectors allow less).

A water heater is set in an attic where a leak could damage the building, so a drain pan is installed. The pan itself must be at least how deep?

• a.1/2 in deep
• b.1-1/2 in deep✓
• c.12 in deep
• d.6 in deep

A water-heater drain pan must be at least 1-1/2 in deep and piped with a minimum 3/4 in indirect drain to an approved point (UPC 507.5 / IPC 504.7). 1/2 in is too shallow to hold a leak, and 6 or 12 in is deeper than required.

At a two-handle fixture fitting, which side is the hot water on as the user faces the fixture?

• a.The bottom
• b.The right
• c.Either side
• d.The left✓

By long-standing convention and code, hot water is supplied on the left and cold on the right at a fitting (IPC 607.1), so users can predict which handle delivers hot water. Reversing them is a scald hazard, and the arrangement is not optional.

What is the maximum flush volume permitted for a water closet under the model-code water-use limits?

• a.1.0 gpf
• b.1.6 gpf✓
• c.3.5 gpf
• d.1.28 gpf

The maximum is 1.6 gallons per flush (IPC 604.4 / EPAct). 1.28 gpf is a high-efficiency level below the maximum, 3.5 gpf is a pre-1994 volume no longer permitted, and 1.0 gpf is a urinal-range value.

What is the maximum flow rate for a residential lavatory faucet at 60 psi?

• a.2.2 gpm✓
• b.0.5 gpm
• c.1.5 gpm
• d.2.5 gpm

A residential lavatory faucet is limited to 2.2 gpm at 60 psi (IPC 604.4). 2.5 gpm is the showerhead limit at 80 psi, and 0.5 gpm applies to public metering/lavatory faucets, not a residential faucet.

What is the maximum flow rate for a public lavatory faucet (other than metering)?

• a.0.5 gpm✓
• b.0.25 gpm
• c.2.2 gpm
• d.2.5 gpm

A public lavatory faucet is limited to 0.5 gpm (IPC 604.4). 0.25 gallon is the per-cycle limit for a metering faucet (a volume, not a flow rate), 2.2 gpm is the residential lavatory limit, and 2.5 gpm is the showerhead limit.

How must the floors of a commercial kitchen with food-prep and wash areas be arranged for drainage?

• a.No drains are needed
• b.The floors are graded to floor drains or floor sinks✓
• c.Carpet is acceptable
• d.Provided with floor drains only in the attached restrooms, not on the cook line

Commercial kitchen floors must be sloped to floor drains or floor sinks so wash-down and spillage drain away, keeping the surface sanitary. Omitting drains or using carpet is not acceptable in a food-service wet area.

A hydromechanical (point-of-use) grease interceptor requires what on its inlet side?

• a.A food grinder discharging into it
• b.A flow-control fitting with an air (vent) intake ahead of it✓
• c.A connection downstream of a water closet
• d.No flow control

A hydromechanical grease interceptor must have a flow-control fitting with an air intake so influent is limited to the rated flow and grease can separate (IPC 1003.3.1). A disposer or water-closet waste is prohibited from a grease interceptor.

A large gravity grease interceptor for a restaurant is usually located:

• a.Outdoors, underground, with manhole access✓
• b.In the attic
• c.Inside the walk-in cooler
• d.Directly under the kitchen sink where it is easiest to reach

A large gravity grease interceptor is a buried tank located outdoors with manhole access so it can be pumped, sized for many minutes of retention. A small hydromechanical unit is the type placed under a sink; the other locations are not serviceable.

A commercial laundry with washing machines must discharge through what interceptor to protect the drainage system?

• a.A lint interceptor or trap✓
• b.No interceptor
• c.A grease interceptor sized for the washing machines
• d.An oil interceptor

Commercial laundry waste carries lint and string that clog drains, so it must pass through a lint interceptor with a removable screen (IPC 1003.6). A grease or oil interceptor targets different contaminants.

A facility that discharges sand and grit, such as a car wash, must drain through:

• a.No interceptor
• b.A lint trap
• c.A grease interceptor ahead of the connection
• d.A sand or solids interceptor✓

Sand and heavy solids must settle out in a sand/solids interceptor before the water enters the sewer (IPC 1003.7). A grease or lint device is designed for fats or fibers, not grit, and would not capture settling solids.

What is the minimum supply pipe size for a flush-tank water closet?

• a.3/8 in✓
• b.1/2 in
• c.1 in
• d.1/4 in

A flush-tank water closet requires a minimum 3/8 in supply (IPC Table 604.5), since the tank refills slowly between flushes. A flushometer water closet, by contrast, needs a 1 in supply for its high instantaneous draw.

What is the minimum supply pipe size for a bathtub?

• a.1/2 in✓
• b.3/8 in
• c.1 in
• d.3/4 in

A bathtub requires a minimum 1/2 in supply (IPC Table 604.5). 3/8 in serves a water-closet tank or lavatory, and 3/4 in or 1 in is larger than a tub requires.

What is the minimum diameter of a residential clothes-washer standpipe?

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

A clothes-washer standpipe must be a minimum of 2 in in diameter to handle the pump's high discharge rate without overflowing (IPC 802.4). 1-1/2 in and 1-1/4 in are undersized, and 3 in exceeds the minimum.

A clothes-washer standpipe trap must be located at what height above the floor?

• a.At the ceiling
• b.48 in above the floor
• c.Below the floor
• d.6 in to 18 in above the floor✓

The standpipe trap must be set between 6 in and 18 in above the floor (IPC 802.4), keeping the seal accessible and at a workable height while the standpipe rises above it. Below the floor or at the ceiling is outside the allowed range.

The floor of a shower compartment must slope to the drain at a minimum of:

• a.1/4 in per ft✓
• b.1/8 in per ft
• c.1 in per ft
• d.1/2 in per ft

A shower floor must slope to the drain at not less than 1/4 in per ft (about 2 percent) so water does not stand (UPC 408.5 / IPC 417.5.2). 1/8 in per ft is too flat and 1/2 in or 1 in per ft is steeper than required and awkward to stand on.

A model-code showerhead is limited to 2.5 gpm at 80 psi. Where several showerheads serve one shower compartment, many codes limit the flow to:

• a.1.5 gpm
• b.2.5 gpm combined for the compartment✓
• c.2.0 gpm
• d.5.0 gpm

The model-code maximum is 2.5 gpm per showerhead at 80 psi, and many adopted codes limit the combined flow of all heads serving one compartment to 2.5 gpm as well, so confirm the adopted code. Treating each head as a separate 2.5 gpm allowance can exceed the limit.

What is the minimum drain size for a commercial food-waste grinder (disposer)?

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

A commercial food-waste grinder requires a minimum 2 in drain and trap because of the volume and character of its discharge (IPC 704 / manufacturer listing). 1-1/2 in serves a residential disposer, and 1-1/4 in is far too small.