Utah Journeyman Plumber Exam: Practice Test & Licensing Guide

Using the building drain sizing table, what is the maximum number of drainage fixture units (dfu) that may be connected to a 4-inch building drain installed at a slope of 1/4 inch per foot?

Answer: 216 dfu

Table 710.1(1) (building drains and sewers) lists a 4-inch pipe at 180 dfu at 1/8 inch per foot, 216 dfu at 1/4 inch per foot and 250 dfu at 1/2 inch per foot. At 1/4 inch per foot the limit is 216 dfu. The 160 dfu figure comes from Table 710.1(2) for a 4-inch horizontal fixture branch, which is the wrong table for a building drain.

Reference: 2021 International Plumbing Code, Table 710.1(1)

A fixture has a 2-inch trap and its fixture drain slopes 1/4 inch per foot. What is the maximum developed length from the trap weir to the vent fitting?

Answer: 8 feet

Table 909.1 lists the maximum distance of a fixture trap from its vent: 1-1/4 inch trap 5 feet, 1-1/2 inch 6 feet, 2 inch 8 feet, 3 inch 12 feet and 4 inch 16 feet. The 2-inch row gives 8 feet at 1/4 inch per foot. The 6-foot answer is the 1-1/2 inch row, a common misread.

Reference: 2021 International Plumbing Code, Table 909.1

The static water pressure at a new building is 95 psi. What does the code require?

Answer: An approved pressure-reducing valve with strainer to reduce static pressure in the building to not more than 80 psi

Section 604.8 requires an approved pressure-reducing valve (ASSE 1003 or CSA B356) with a strainer where static pressure within a building exceeds 80 psi, reducing it to not more than 80 psi static. Sillcock and outside hydrant lines may be exempted. An expansion tank controls thermal expansion (Section 607.3) and does not reduce supply pressure.

Reference: 2021 International Plumbing Code, Section 604.8

A faucet spout with a 3/4-inch effective opening discharges into a sink, and the spout is close to a wall. What is the minimum required air gap?

Answer: 2-1/2 inches

Table 608.16.1 lists fixtures with effective openings not greater than 3/4 inch (sinks, laundry trays, gooseneck faucets) at 1-1/2 inches away from a wall and 2-1/2 inches close to a wall. Because the spout is near the wall, 2-1/2 inches applies. The air gap is measured from the lowest end of the outlet to the flood level rim (Section 608.14.1).

Reference: 2021 International Plumbing Code, Table 608.16.1

An indirect waste pipe from a commercial ice machine runs 40 inches horizontally to a floor sink. What does the code require for this pipe?

Answer: It must be trapped, because it exceeds 30 inches of horizontal developed length

Section 802.3 requires indirect waste piping that exceeds 30 inches in developed length measured horizontally, or 54 inches in total developed length, to be trapped. At 40 inches horizontal, this pipe must be trapped. The receptor itself must also be trapped and vented, and the pipe must discharge through an air gap or air break.

Reference: 2021 International Plumbing Code, Section 802.3

You are filling 100 feet of 4-inch building drain for a water test. Treating 4 inches as the inside diameter, about how many gallons of water will the pipe hold? (1 cubic foot = 7.48 gallons)

Answer: 65.3 gallons

Radius = 2 in = 0.1667 ft. Area = pi x 0.1667^2 = 0.08727 sq ft. Volume = 0.08727 x 100 ft = 8.727 cu ft, and 8.727 x 7.48 = 65.3 gallons. Using the diameter as the radius gives 261.1 gallons, stopping at cubic feet gives 8.7, and leaving out pi gives 20.8. Section 312.2 requires the system to be filled to the point of overflow for this test.

Reference: 2021 International Plumbing Code, Section 312.2

An inspector finds that a 4-inch horizontal building drain falls 3 inches over a 50-foot run. What is its slope, and does it comply with Table 704.1?

Answer: 0.06 inch per foot; it does not meet the 1/8-inch-per-foot minimum

Slope = fall / run = 3 in / 50 ft = 0.06 inch per foot. Table 704.1 requires 1/8 inch per foot (0.125) for 3- to 6-inch pipe, so the drain fails. The 1/16-inch minimum applies only to 8-inch and larger pipe, and 0.25 comes from dividing 3 by 12 instead of by the 50-foot run.

Reference: 2021 International Plumbing Code, Table 704.1

A plumber is setting pipe on a walking/working surface with an unprotected edge. At what height above a lower level must the employee be protected by guardrails, a safety net or a personal fall arrest system?

Answer: 6 feet or more

29 CFR 1926.501(b)(1) requires fall protection for each employee on a walking/working surface with an unprotected side or edge 6 feet or more above a lower level. The 10-foot figure is the scaffold trigger in 1926.451(g)(1), and 4 feet is the trench depth that triggers means of egress in 1926.651(c)(2).

Reference: 29 CFR Part 1926 (OSHA Safety and Health Regulations for Construction), 29 CFR 1926.501(b)(1)

What is the maximum horizontal hanger spacing for 3/4-inch PEX water distribution tubing?

Answer: 32 inches (2.67 feet)

Table 308.5 lists PEX pipe 1 inch and smaller at a maximum horizontal spacing of 2.67 feet (32 inches), and PEX 1-1/4 inches and larger at 4 feet. Six feet applies to copper tubing 1-1/4 inches and smaller, and 10 feet is PEX's vertical support spacing.

Reference: 2021 International Plumbing Code, Table 308.5

A natural gas system (inlet pressure less than 2 psi, 0.5 in. w.c. pressure drop, 0.60 specific gravity) uses Schedule 40 steel pipe. The longest run is 50 feet and one section carries 120 cubic feet per hour. Using Table 402.4(2), what is the minimum pipe size for that section?

Answer: 3/4 inch

In Table 402.4(2) at the 50-foot row, 1/2-inch pipe carries 72 cfh and 3/4-inch carries 151 cfh. Since 120 cfh is more than 72 but no more than 151, 3/4 inch is the smallest size that works. Under the longest-length method of Section 402.4.1, the 50-foot row is used for every section. Picking 1 inch (284 cfh) is oversizing, not the minimum.

Reference: 2021 International Fuel Gas Code, Table 402.4(2) and Section 402.4.1