Journeyman Plumber (UPC/IPC) — All Questions

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

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

A residential disposer discharges through the kitchen-sink drain and requires a minimum 1-1/2 in drain and trap. 1-1/4 in is the lavatory minimum and is undersized for a disposer, while 2 in is the commercial-grinder minimum.

What is the minimum trap and drain size for a bathtub?

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

A bathtub requires a minimum 1-1/2 in trap and drain (IPC Table 709.1). 1-1/4 in is the lavatory minimum and is undersized for a tub, and 2 in or 3 in exceeds what a tub requires.

An emergency eyewash or drench shower for worker safety must deliver tepid water in what temperature range?

• a.32 to 50 degrees F
• b.About 140 degrees F
• c.110 to 120 degrees F
• d.60 to 100 degrees F✓

Emergency eyewash and shower equipment must deliver tepid flushing fluid, generally 60 to 100 degrees F (ANSI/ISEA Z358.1), so a victim can tolerate a full flush without cold shock or scalding. 110 degrees and above is a scald risk and near-freezing water drives victims off the unit.

A bathtub trap and its waste-and-overflow concealed in a wall or floor must be provided with:

• a.No access, since it is concealed
• b.A wall that is cut open each time service is needed
• c.The overflow opening only
• d.An access panel or other approved access to the trap and waste✓

Concealed slip-joint connections such as a tub waste-and-overflow must remain accessible through an access panel or removable access so the joints can be serviced (IPC 405.8 / 712 access rules). Sealing them permanently behind finished construction is not permitted.

To control Legionella growth, stored hot water in a water heater is generally kept at a minimum of about:

• a.110 degrees F
• b.90 degrees F
• c.180 degrees F
• d.140 degrees F✓

Storing water at about 140 degrees F suppresses Legionella, while the water delivered to fixtures is tempered down (for example to 110 degrees F at public lavatories) with a mixing valve to prevent scalding. 90 and 110 degrees are within the range where the bacteria thrive.

A fuel-fired water heater installed in a bathroom or a bedroom must be:

• a.Any atmospheric-vented type
• b.Prohibited entirely
• c.Limited to an electric water heater only, because no gas-fired unit of any kind may ever be placed in a bedroom or bathroom
• d.A direct-vent or sealed-combustion type, or installed in a sealed enclosure with combustion air from outdoors✓

A fuel-burning water heater in a bedroom or bathroom must be a direct-vent unit or be enclosed in a sealed room that draws combustion air from outdoors, so occupants are not exposed to combustion products in a sleeping or bathing space (IFGC / IRC). An open atmospheric unit is not allowed there.

A house on natural gas (about 1,000 Btu per cubic foot) has an 80,000 Btu/h furnace, a 30,000 Btu/h water heater, and a 30,000 Btu/h range. What total flow must the piping downstream of the meter carry?

• a.56 cfh
• b.14 cfh
• c.140 cfh✓
• d.1,400 cfh

Total load is 80,000 + 30,000 + 30,000 = 140,000 Btu/h, and dividing by 1,000 Btu per cubic foot gives 140 cfh. 14 and 1,400 misplace a decimal, and 56 comes from dividing by 2,500 (a propane value).

A propane appliance load totals 125,000 Btu/h. Using about 2,500 Btu per cubic foot for propane vapor, what flow must the piping carry?

• a.50 cfh✓
• b.125 cfh
• c.31 cfh
• d.500 cfh

For propane, cfh = Btu/h / 2,500, so 125,000 / 2,500 = 50 cfh. 125 cfh uses the 1,000 Btu natural-gas value, 500 cfh divides by an incorrect small value, and 31 cfh uses about 4,000 Btu per cubic foot, which no common fuel gas has.

The most remote gas outlet measures 62 ft from the meter, and the sizing table is printed in 10 ft increments. Which length row is used?

• a.70 ft✓
• b.62 ft
• c.60 ft
• d.50 ft

When the developed length falls between rows, the next longer row is used, so 62 ft is sized from the 70 ft column. Rounding down to 60 ft (or 50 ft) allows more pressure drop than the table assumes and undersizes the pipe.

At 50 ft, a natural-gas table shows 1/2 in pipe rated for 56 cfh and 3/4 in for 115 cfh. A section must carry 60 cfh. What is the smallest pipe that works?

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

The pipe must carry at least 60 cfh; 1/2 in is rated for only 56 cfh, which is below the demand, so you step up to 3/4 in at 115 cfh. Choosing 1/2 in starves the appliance, and 1 in is larger than needed once 3/4 in covers the load.

What is the purpose of a sediment trap (drip leg) ahead of an appliance control valve?

• a.It regulates the gas pressure
• b.It collects moisture and debris before they reach the appliance control valve✓
• c.It acts as the shutoff valve
• d.It vents the regulator

A sediment trap is a capped drip pocket that catches moisture and scale carried in the gas so they do not foul the appliance control valve (IFGC 408.4). It does not regulate pressure, shut off gas, or vent a regulator.

What is the maximum length of a listed appliance connector serving a furnace (not a range or dryer)?

• a.3 ft✓
• b.1 ft
• c.6 ft
• d.10 ft

Most appliance connectors are limited to 3 ft (IFGC 411). Ranges and clothes dryers are the exception, permitted up to 6 ft; a furnace connector is held to the 3 ft general limit.

A listed appliance connector may:

• a.Pass through a wall if it is sleeved
• b.Be joined to a second connector to gain length
• c.Be reused from a previous appliance
• d.Not pass through walls, floors, ceilings, or partitions✓

An appliance connector may not pass through any wall, floor, ceiling, or partition, may not be concealed, and may not be joined to another connector or reused (IFGC 411). Where those conditions arise, rigid pipe must be run to a valve near the appliance.

Threaded black-steel gas pipe joints are made up with:

• a.Solvent cement
• b.An approved gas-rated thread sealant (pipe dope), or PTFE tape listed for gas✓
• c.A wax ring
• d.A rubber gasket slip coupling

Steel gas-pipe threads are sealed with a joint compound or tape listed as resistant to the gas (IFGC 403.9.2). Solvent cement is for plastic, a wax ring seals a closet, and a rubber slip coupling is a drainage fitting, none rated for gas joints.

Copper tube may be used for natural gas only when:

• a.Only when painted
• b.Never permitted for natural gas under any condition, since sulfur always attacks it
• c.Only when buried underground
• d.The gas is not corrosive (limited hydrogen sulfide content)✓

Copper is permitted for fuel gas only where the gas is not corrosive to copper, meaning the hydrogen sulfide content is below the code limit (IFGC 403.4.3), because sulfur attacks copper. It is not categorically prohibited, and burial or paint is not the deciding factor.

Where is a drip leg (drip) installed in a fuel-gas piping system?

• a.Never in residential work
• b.At low points where condensate can collect, and commonly at each appliance✓
• c.Only on outdoor piping
• d.At the highest point of the system

A drip is installed at low points where liquid can collect and typically at each appliance connection so moisture is trapped before it reaches the control (IFGC 408). Placing it at the high point would defeat the purpose, and drips are used in residential systems.

Compared with air, LP-gas (propane) vapor is:

• a.Heavier than air, so it settles at low points✓
• b.Nonflammable
• c.Lighter than air, so it rises to the ceiling
• d.The same density as air

Propane vapor is heavier than air and pools in low areas such as pits, basements, and floor level, which is why LP appliances and gas detectors account for low accumulation. Natural gas, by contrast, is lighter than air and rises.

A 250-gallon propane tank is filled to the maximum safe fill of 80 percent. How many gallons of liquid propane does it hold?

• a.250 gal
• b.125 gal
• c.200 gal✓
• d.150 gal

A propane tank is filled to a maximum of 80 percent to leave room for vapor expansion, so 250 x 0.80 = 200 gal. Filling to 250 gal (100 percent) is unsafe, and 125 or 150 gal understates the 80 percent fill.

A propane appliance with an input of 100,000 Btu/h runs continuously. Using about 91,500 Btu per gallon, roughly how long will 100 gallons last?

• a.46 hours
• b.9 hours
• c.183 hours
• d.91.5 hours✓

100 gallons holds 9,150,000 Btu, and 9,150,000 / 100,000 = 91.5 hours. Doubling the burn rate gives 46 hours, halving it gives 183 hours, and 9 hours misplaces a decimal.

What is the approximate heating value of propane vapor?

• a.About 1,000 Btu per cubic foot
• b.About 500 Btu per cubic foot
• c.About 2,500 Btu per cubic foot✓
• d.About 91,500 Btu per cubic foot

Propane vapor carries about 2,500 Btu per cubic foot, roughly two and a half times natural gas at about 1,000 Btu per cubic foot. The 91,500 figure is the energy per gallon of liquid propane, not per cubic foot of vapor.

A residence is served by a 2 psi gas system, but the appliances require about 7 in w.c. What is installed to make this work?

• a.A check valve
• b.A larger gas meter
• c.Nothing is required, because the utility service regulator already delivers the correct appliance pressure
• d.A line pressure regulator, with overpressure protection, to step the pressure down✓

An elevated-pressure (2 psi) system requires a line pressure regulator, with downstream overpressure protection, to reduce the pressure to the roughly 7 in w.c. the appliances need (IFGC 410). A larger meter or a check valve does not regulate delivery pressure.

After a gas piping system is tested and put into service, it is purged of air:

• a.Purging is not required
• b.Through an appliance burner only
• c.To the outdoors, away from ignition sources✓
• d.Into the building through a window

Piping must be purged to the outdoors or to a safe point away from any ignition source, never into an occupied space, so an air-gas mixture cannot accumulate and ignite (IFGC 406.7). Purging is required whenever a system is placed in or returned to service.

How must vertical gas piping be supported?

• a.It is never required to be supported, since the fittings alone carry the weight of the riser
• b.Every 2 ft
• c.At each floor level, and at intervals that prevent movement✓
• d.Only at the top of the riser

Vertical gas piping must be supported at each floor level (and at intervals for larger pipe) so its weight is carried and it cannot shift and stress the joints (IFGC 415). Supporting only the top, or not at all, leaves the riser unsupported.

A gas meter must be located:

• a.In a ventilated, accessible location clear of ignition sources and building openings✓
• b.Inside a sealed closet
• c.Inside a return-air plenum
• d.Below grade inside a covered pit in every case, so that the meter is protected from the weather

A gas meter is placed in a ventilated, accessible location where a leak can disperse and away from ignition sources, windows, and air intakes. A sealed closet or a return-air plenum would trap or distribute leaking gas.

What is the minimum depth of cover for underground gas piping in an area with no vehicle traffic?

• a.36 in
• b.24 in
• c.6 in
• d.12 in✓

Underground gas piping requires at least 12 in of cover in general (IFGC 404.12). 6 in leaves the pipe vulnerable to damage, and 24 or 36 in is deeper than the general minimum (deeper cover applies under driveways and roads).

What is the minimum depth of cover for underground gas piping installed beneath a private driveway?

• a.6 in
• b.36 in
• c.12 in
• d.18 in✓

Under a driveway or parking area the cover is increased to at least 18 in to protect the pipe from vehicle loads (IFGC 404.12). The 12 in general minimum is not enough under traffic, and 6 in is far too shallow.

Which of the following is prohibited in a concealed gas-piping location?

• a.A straight, unbroken length of pipe with no fittings at all
• b.A union, bushing, or right-and-left coupling✓
• c.A welded joint
• d.An elbow

Unions, bushings, swing joints, and right-and-left couplings are prohibited in concealed locations because they are the joints most likely to loosen and leak where no one can inspect them (IFGC 404.5). Welded joints and standard fittings on run pipe are permitted concealed.

On detecting a gas leak in a building, which action must you NOT take?

• a.Operating electrical switches or creating any spark or flame✓
• b.Shutting the gas off at the meter if it is safe to do so
• c.Leaving the area
• d.Calling the utility from outside the building

You must not operate electrical switches, light a flame, or do anything that could create a spark, since any of these can ignite an accumulated gas-air mixture. The correct steps are to evacuate, shut off the gas if safe, and call the utility from a safe location outside.

A DWV section is water tested. The highest joint in the section is 24 ft above the building drain, and more piping continues above this section. To what height above the building drain must the test standpipe extend?

• a.10 ft
• b.24 ft
• c.29 ft
• d.34 ft✓

The water test requires at least a 10 ft head on the highest point of the section, so the standpipe must rise 24 + 10 = 34 ft above the building drain (IPC 312.2). Stopping at 24 ft puts no head on the top joint; the 10 ft exception does not apply because piping continues above.

What is the normal sequence of plumbing inspections?

• a.Final, then rough, then groundwork
• b.Groundwork/underground, then rough-in/top-out, then final✓
• c.In any order the contractor prefers
• d.Rough, then final, then groundwork

Inspections follow the order of construction: underground/groundwork first, then rough-in (top-out) before concealment, then the final inspection when fixtures are set (IPC 107). No portion may be covered until it has been inspected and approved.

A floor plan is drawn at a scale of 1/8 in = 1 ft. A run of pipe measures 5 in on the drawing. What is its actual length?

• a.20 ft
• b.64 ft
• c.5 ft
• d.40 ft✓

At 1/8 in = 1 ft, each inch on the drawing equals 8 ft, so 5 in x 8 ft = 40 ft. Reading 5 ft ignores the scale, 20 ft multiplies by 4, and 64 ft multiplies inches the wrong way.

A floor plan is drawn at 1/4 in = 1 ft. A pipe run measures 2-1/2 in on the drawing. What is its actual length?

• a.2-1/2 ft
• b.10 ft✓
• c.5 ft
• d.20 ft

At 1/4 in = 1 ft, each inch equals 4 ft, so 2.5 in x 4 ft = 10 ft. 2-1/2 ft repeats the measured inches as feet, 5 ft multiplies by 2, and 20 ft multiplies by 8.

A site plan shows a sewer invert of 105.00 ft upstream and 104.40 ft downstream over a 40 ft run. What is the slope in inches per foot?

• a.0.018 in per ft
• b.0.125 in per ft
• c.0.18 in per ft✓
• d.0.15 in per ft

The fall is 105.00 - 104.40 = 0.60 ft = 7.2 in, and 7.2 in / 40 ft = 0.18 in per ft. 0.018 is the value in feet per foot (off by a factor of 12), and 0.125 (1/8 in per ft) would give only 5 in of fall over 40 ft.

A building sewer runs 50 ft at 1/4 in per ft. The upstream invert is 100.00 ft. What is the downstream invert elevation?

• a.99.48 ft
• b.98.96 ft✓
• c.101.04 ft
• d.98.75 ft

Fall = 50 ft x 1/4 in = 12.5 in = 1.04 ft, so 100.00 - 1.04 = 98.96 ft. 99.48 ft halves the fall (as if 1/8 in per ft), 101.04 ft runs the sewer uphill, and 98.75 ft rounds the fall incorrectly.

A 8 ft deep trench with a 4 ft wide bottom is dug in Type B soil and sloped at 1 to 1. How wide must the excavation be at the top?

• a.12 ft
• b.24 ft
• c.20 ft✓
• d.16 ft

Type B soil is sloped 1 horizontal to 1 vertical, so each wall lays back 1 x 8 = 8 ft. Both walls sloped gives 4 + 8 + 8 = 20 ft at the top (OSHA 1926 Subpart P, Appendix B). Adding the layback to one side only gives 12 ft, and Type C (1.5:1) would give 24 ft.

A 6 ft deep trench with a 3 ft wide bottom is dug in Type A soil and sloped at 3/4 to 1. How wide must the excavation be at the top?

• a.9 ft
• b.15 ft
• c.12 ft✓
• d.18 ft

Type A soil is sloped 3/4 horizontal to 1 vertical, so each wall lays back 0.75 x 6 = 4.5 ft. With both walls sloped, 3 + 4.5 + 4.5 = 12 ft at the top. Adding one layback gives 9 ft; a 1:1 slope would give 15 ft.

A trench 120 ft long and 5 ft deep has workers along its full length. What is the minimum number of ladders (or other means of egress) required?

• a.3✓
• b.1
• c.2
• d.5

In a trench 4 ft or deeper, a means of egress must be within 25 ft of lateral travel of every worker, so each ladder covers 50 ft of trench (OSHA 1926.651). 120 / 50 = 2.4, rounded up to 3 ladders. Two ladders leave workers more than 25 ft from egress.

How often must the competent person inspect an excavation where workers are exposed?

• a.Daily and before each shift, and after rain or other events that increase hazards✓
• b.Once a week
• c.Once a month
• d.Only at the start of the job

The competent person must inspect the excavation daily and before each shift, and again after any rainstorm or other hazard-increasing event, removing workers if a hazard is found (OSHA 1926.651(k)). Weekly or one-time inspection does not meet the rule.

Before entry into a confined space, the atmosphere reads 23.8 percent oxygen. What does this indicate?

• a.A safe, normal atmosphere
• b.An oxygen-enriched atmosphere, an increased fire and explosion hazard✓
• c.A meter error to be ignored
• d.An oxygen-deficient atmosphere

An acceptable atmosphere is 19.5 to 23.5 percent oxygen, so 23.8 percent is oxygen-enriched, which greatly increases fire and explosion risk and prohibits entry until corrected (OSHA 1910.146). It is neither normal nor deficient, and the reading must not be ignored.

Entry into a permit-required confined space such as a sewer manhole requires:

• a.Nothing special
• b.Only a filtering facepiece respirator and a co-worker standing nearby to watch the entrant
• c.Only a flashlight
• d.An entry permit, an attendant, atmospheric testing, and rescue/retrieval provisions✓

A permit-required confined space entry requires a signed entry permit, atmospheric testing, an attendant posted outside, and rescue/retrieval means, along with any needed ventilation and supplied-air respirators (OSHA 1910.146). A filtering facepiece cannot add oxygen and is not sufficient.

What personal protective equipment is required when cutting or grinding pipe?

• a.Eye and face protection such as safety glasses or a face shield✓
• b.Only gloves
• c.Only a hard hat
• d.No PPE is needed

Cutting and grinding throw chips and sparks, so eye and face protection is required, and a face shield is added over safety glasses for grinding (OSHA 1926.102). Gloves or a hard hat alone do not protect the eyes.

A portable ladder used to access a landing (such as the top of a trench) must extend above the landing surface by at least:

• a.6 in
• b.3 ft✓
• c.6 ft
• d.1 ft

A portable ladder used for access must extend at least 3 ft above the upper landing so a worker has something to hold while stepping off (OSHA 1926.1053). 1 ft or 6 in leaves nothing to grasp at the top.

Portable electric power tools on a construction site must be protected by:

• a.Nothing
• b.GFCI protection (or an assured equipment grounding conductor program)✓
• c.A fuse only
• d.A household power strip

Receptacles supplying portable tools on a jobsite must have ground-fault circuit-interrupter protection, or the employer must run an assured equipment grounding conductor program (OSHA 1926.404). A fuse or a power strip does not protect against electrocution.

Where do you find the hazard and handling information for PVC primer and solvent cement?

• a.The building permit
• b.The plumbing code book
• c.The Safety Data Sheet (SDS)✓
• d.The supplier invoice

The Safety Data Sheet (SDS) provides the flammability, exposure, first-aid, and handling information for chemical products such as primer and cement, and must be available to workers under the Hazard Communication standard (OSHA 1910.1200). The permit and code do not carry that data.

ABS and PVC DWV pipe are joined by:

• a.Solvent cement, using the primer and cement listed for the material✓
• b.Soldered joints
• c.Crimp rings
• d.Threaded joints

Rigid plastic DWV pipe is joined with solvent cement, with PVC requiring a primer and PVC cement and ABS using ABS cement (never interchanged). Threading, soldering, and crimping apply to metal or flexible materials, not solvent-welded plastic.

A hub-and-spigot (bell-and-spigot) cast-iron soil pipe joint is made with:

• a.A compression (rubber) gasket, or molten lead and oakum✓
• b.A wax ring
• c.Pipe-thread dope
• d.Solvent cement

A hub-and-spigot cast-iron joint is made either with a compression rubber gasket pushed into the hub or, in the traditional method, with oakum packing caulked and molten lead poured over it. Solvent cement, wax rings, and thread dope are for other materials and fittings.

Copper tube is joined by:

• a.Solvent cement
• b.Crimp rings only
• c.Threaded joints only
• d.Soldered or brazed joints, or approved press or mechanical fittings✓

Copper tube is joined by soldering or brazing, or with listed press and mechanical fittings (IPC 605). Solvent cement is for plastic, copper water tube is not field-threaded, and crimp rings are a PEX method.

Piping run through a wood stud less than 1-1/4 in from the edge must be protected by:

• a.A larger drill bit
• b.Nothing
• c.A steel nail (shield) plate✓
• d.A wrap of tape

Where a pipe is closer than 1-1/4 in to the edge of a stud or plate, a steel nail plate (shield plate) must cover the area to stop nails and screws from puncturing the pipe (IPC 305.6). Tape provides no such protection.

A pipe that penetrates a fire-rated wall or floor assembly must be:

• a.Left open around the pipe
• b.Wrapped in cloth
• c.Coated with grease
• d.Sealed with an approved firestop system that maintains the fire rating✓

A penetration of a fire-rated assembly must be sealed with a tested, approved firestop system so the assembly keeps its fire-resistance rating (IPC 305 / IBC firestopping). Leaving the annular space open, or stuffing it with cloth, defeats the rating.