Exam Cheat Sheet · Quick Reference
ICC G28 Journeyman Plumber with Gas Exam (2018 IPC/IFGC)
National · Pearson Vue
National State Portion 70 questions
Key Distinctions
Full-open valves are required at locations such as the discharge side of every water meter, the water supply pipe to every water heater, the entrance to the structure, and the base of every water riser pipe (in occupancies other than multiple-family residential two stories or less and one- and two-family dwellings), while shutoff valves are what is required at individual fixture supplies.
IPC 2018 Sections 606.1 and 606.2A horizontal pipe is any pipe or fitting making an angle of less than 45 degrees with the horizontal plane, while a vertical pipe makes an angle of 45 degrees or more with the horizontal (so a pipe at 40 degrees is horizontal).
IPC 2018 Chapter 2 — Section 202, definitions of Horizontal Pipe and Vertical PipeA stack vent is the extension of a soil or waste stack above the highest horizontal drain connected to that stack, whereas a vent stack is a vertical vent pipe installed primarily to provide circulation of air to and from the drainage system.
IPC 2018 Chapter 2 — Section 202, definitions of Stack Vent and Vent StackAn appurtenance is an adjunct to the basic piping system and fixtures that demands no additional water supply and adds no discharge load to a fixture or the drainage system, while devices dependent on energized components are plumbing appliances.
IPC 2018 Chapter 2 — Section 202, definitions of Plumbing Appurtenance and Plumbing ApplianceBoth are prohibited traps, but the S-trap is prohibited with no exception, while drum traps have an exception permitting use as solids interceptors and for chemical waste systems.
IPC 2018 Section 1002.3Under the longest length method every section and branch is sized from the table row for the system's total longest run (e.g., a 12-ft branch still uses the 70-ft row), while under the branch length method each branch is sized using its own length measured from the meter (e.g., 15 ft of main + 8 ft of branch = 23 ft → the 30-ft row).
IFGC Section 402.4.1, Longest Length Method; Table 402.4(2), Schedule 40 Metallic Pipe (natural gas, 0.5 in. w.c. drop)For Category I appliances, excluding engineered systems, a single-wall connector's maximum horizontal length is 75 percent of the chimney/vent height, while a Type B double-wall connector is permitted 100 percent of the chimney height.
IFGC 2018 Section 503.10.8Horizontal-duct openings each require not less than 1 square inch per 2,000 Btu/h of total input; openings communicating directly with the outdoors or through vertical ducts use 1 square inch per 4,000 Btu/h, and the one-permanent-opening method (IFGC 304.6.2) uses 1 square inch per 3,000 Btu/h.
IFGC 2018 to 23 (Section 304.6.1)Potable water-supplied trap seal primer valves conform to ASSE 1018, while ASSE 1044 applies to waste water-supplied trap primer devices and ASSE 1072 applies to barrier-type trap seal protection devices.
IPC 2018 Section 1002.4.1.1Urinals shall not be substituted for more than 67 percent of required water closets in assembly and educational occupancies, while the limit is 50 percent in all other occupancies.
IPC 2018 Section 424.2The general exception threshold is a maximum occupant load of 15, while business occupancies are exempt from separate facilities only where the maximum occupant load is 25 or fewer; at an occupant load of 30 neither exception applies and separate facilities are required.
IPC 2018 Section 403.2 Exception 4Detached one- and two-family dwellings and multiple single-family dwellings (townhouses) not more than three stories high with separate means of egress, plus their accessory structures, comply with the IRC; buildings exceeding three stories and other occupancies such as hotels and apartment buildings remain under the IPC.
IPC 2018 Chapter 1 — Section 101.2 ScopePot sinks, prerinse sinks and floor drains into which kettles are drained must discharge through a grease interceptor (1003.3.1), but a food waste disposer shall not discharge to a grease interceptor (1003.3.2).
IPC 2018 Section 1003.3.2Key Terms
Formulas to Know
Capacity = 6 cubic feet for the first 100 sq ft of area drained + 1 cubic foot for each additional 100 sq ft (minimum). Worked examples: 500 sq ft → 6 + (4 × 1) = 10 cu ft; 400 sq ft → 6 + 3 = 9 cu ft.Capacity = peak drain flow (gpm) × 30-minute retention time. Worked example: 40 gpm × 30 = 1,200 gallons.Not less than 6 inches below the frost line and not less than 12 inches below grade. Worked example: frost line 18 in → 18 + 6 = 24 inches.Extend from the wall at each side not less than 18 inches, or to not less than 6 inches beyond the outermost front lip measured from the finished backwall surface, whichever is greater. Worked example: 14-in lip → 14 + 6 = 20 inches governs.cfh = total Btuh input ÷ 1,000. Worked examples: 40,000 ÷ 1,000 = 40 cfh; (40,000 + 65,000 + 30,000) ÷ 1,000 = 135 cfh; (35,000 + 150,000) ÷ 1,000 = 185 cfh.Btuh served = table capacity (cfh) × 1,000 Btu per cu ft. Worked example: 44 cfh × 1,000 = 44,000 Btuh, enough for a 40,000 Btuh gas fireplace.Spare cfh = table capacity at that length − appliance demand. Worked examples: 137 − 80 = 57 cfh spare; 117 − 40 = 77 cfh spare; 44 − 40 = 4 cfh spare; 237 − 230 = 7 cfh margin.Use the next-larger tabulated length row for the run: 15-ft run → 20-ft row; 35-ft run → 40-ft row; 95-ft run → 100-ft row; 140-ft run → 150-ft row (1-1/4 in at 150-ft row = 322 cfh).Section load = sum of the Btuh of all outlets it serves ÷ 1,000, then size from the governing length row. Worked examples: 40,000 + 35,000 + 100,000 = 175 cfh → 1 in at the 70-ft row (237 cfh); 120,000 + 40,000 + 150,000 = 310 cfh → 1-1/4 in at the 90-ft row; 40,000 + 75,000 = 115 cfh → 3/4 in at the 60-ft row.Divide the total occupant load in half (Section 403.1.1), then apply the Table 403.1 ratio. Worked example (restaurant, 1 per 75 female): 150 ÷ 2 = 75; 75 ÷ 75 = 1 water closet.