Exam Cheat Sheet · Quick Reference

ICC G27 Master Plumber with Gas Exam (2018 IPC/IFGC)

National  ·  Pearson Vue

Verified, not estimated. Every figure below is drawn from the official exam structure we maintain — question counts, passing standard and topic weighting. Practice questions are grounded in the source law with statute citations. We omit any figure we can't verify rather than guess at it.
Total questions
100
Passing score
70%
Exam time
240 min
Administered by
Pearson Vue
Format
Reference materials allowed

National State Portion 100 questions

Administration General Regulations 36 Q · 36%
General Installation RequirementsCode Definitions and TermsPlan ReadingTestingMaterialsPermits and permit applicationsInspections and inspection typesCode official authority and dutiesViolations, stop work orders, and penaltiesMeans of appeal and board of appeals proceduresExisting installations, alterations, and change of occupancyPipe protection and structural safety requirements +4 more
Plumbing Fixtures 13 Q · 13%
Water HeatersWater Closets and UrinalsSpecialty FixturesBathtubs, Showers, Sinks, and LavatoriesMinimum Number of Required Plumbing Fixtures by OccupancyFixture Installation Requirements and ClearancesFaucets, Fixture Fittings, and Shower Valve StandardsFlushing Devices for Water Closets and UrinalsFloor Drains, Floor Sinks, and Waste OutletsWater Heater Safety Devices and Relief ValvesWater Heater Installation, Access, and Location RequirementsSeparate Facilities, Accessible Fixtures, and Signage Requirements +1 more
Water Supply and Distribution 9 Q · 9%
Service Distribution and PipingWater Supply and PressureProtection of Potable Water SupplyPipe Materials and Approved Standards for Water Service and DistributionJoining Methods and Connection Requirements by Pipe MaterialFixture Supply Pipe Sizing and Flow Rate RequirementsHot Water Supply System Requirements and Temperature ControlsValve Installation Requirements and LocationsWater Hammer Arrestors and Pressure-Reducing ValvesDisinfection of Potable Water SystemsIndividual Water Supply Sources and Well Construction RequirementsChapter 6 Water Supply and Distribution
Sanitary Drainage 8 Q · 8%
Building Sanitary DrainageSumps and EjectorsIndirect and Special Waste SystemsDrainage pipe materials and applicable standards (above-ground, underground, and building sewer)Pipe joints and connection methods by material typeSlope, sizing, and fixture unit load calculations for drainage systemsCleanout requirements, placement, spacing, and accessDrainage fittings, changes in direction, and prohibited connectionsBackwater valves — installation requirements and applicabilityPipe-bursting methods for replacement of building sewers and drainsVacuum drainage systemsChapter 7 Sanitary Drainage
Plumbing Vent Requirements 6 Q · 6%
Vent Connections and GradesVent TerminalsVent Pipe Sizing and Developed LengthTypes of Venting Methods (Individual, Common, Wet, Circuit, Combination, Island, Single-Stack)Air Admittance ValvesTrap Seal Protection and Fixture Trap Distance from VentVent Stack and Stack Vent RequirementsRelief Vents for Multi-Story StacksOutdoor Vent Extensions and Vent Stack at Base Connections
Traps, Interceptors, and Separators 5 Q · 5%
Installation of TrapsInterceptors and SeparatorsTrap seal depth requirements and protection methodsProhibited trap typesTrap sizing and dimensional limitsGrease interceptor sizing and capacity requirementsOil separator design and capacity requirementsSand interceptors and specialty interceptors (clothes washers, bottling, slaughterhouses)Venting and access requirements for interceptors and separators
Storm Drainage 2 Q · 2%
Storm DrainageSizing of vertical conductors, leaders, and horizontal storm drains using 100-year rainfall rate tablesPrimary and secondary (emergency overflow) roof drain requirements and scupper sizingProhibited connections and disposal requirements for storm waterApproved materials for inside conductors, underground storm drain pipe, building storm sewer pipe, and subsoil drain pipeRoof drain installation requirements and flow rate calculations for system sizingStorm drain traps: when required, sizing, material, and cleanout requirementsSiphonic roof drainage system design standardsHorizontal gutter sizing and vertical wall area calculations
Gas Piping 21 Q · 21%
Gas Piping for Service & Distribution PipingGas Piping Requirements, Specific Appliances EquipmentSource of Combustion Air & Duct OpeningsFuel-burning Appliance, Vent, ConnectorCSST bonding and grounding requirementsPipe sizing methods and sizing tables (longest length, branch length, hybrid pressure)Permitted piping materials, tubing standards, and fitting typesPressure testing procedures, test medium, duration, and leak detectionPiping installation requirements (prohibited locations, underground burial depth, protection against physical damage)Purging of gas piping systems (indoor vs. outdoor discharge requirements)Shutoff valves, pressure regulators, and flow controlsPiping support, drips, sediment traps, and sloped piping requirements +2 more

Key Distinctions

Water service pipevsWater distribution pipe

Per the IPC 2018 Section 202 definitions, the water service pipe runs from the water main or other potable source (or from the meter only where the meter is at the public right of way) to the water distribution system of the building, so when the meter is inside the building the service pipe extends all the way to the building's distribution system and the distribution pipe begins only where the meter is at the structure.

IPC 2018 Chapter 2 — Section 202, definitions of Water Pipe (Water service pipe and Water distribution pipe)
Horizontal pipevsVertical pipe

A horizontal pipe or fitting makes an angle of less than 45 degrees with the horizontal plane (so 40 degrees is horizontal), while a vertical pipe or fitting makes an angle of 45 degrees or more with the horizontal.

IPC 2018 Chapter 2 — Section 202, definitions of Horizontal Pipe and Vertical Pipe
Stack ventvsVent stack

A stack vent is the extension of a soil or waste stack above the highest horizontal drain connected to that stack, while 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 Stack
Plumbing appurtenancevsPlumbing appliance

An appurtenance is an adjunct device that demands no additional water supply and adds no discharge load to a fixture or the drainage system, whereas devices dependent on energized components are plumbing appliances.

IPC 2018 Chapter 2 — Section 202, definitions of Plumbing Appurtenance and Plumbing Appliance
Full-open valve (IPC 606.1)vsShutoff valve (IPC 606.2)

Full-open valves are required at points 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 (in occupancies other than multiple-family residential two stories or less and one- and two-family dwellings), while shutoff valves are the valves required at fixture supplies — with bathtubs and showers in one- and two-family residential occupancies exempt.

IPC 2018 Sections 606.1 and 606.2
Drum trapvsS-trap

Both are prohibited traps under IPC 1002.3, but drum traps have an exception permitting their use as solids interceptors and for chemical waste systems, while S-traps are prohibited with no exception.

IPC 2018 Section 1002.3
Trap seal primer valve (ASSE 1018)vsBarrier-type trap seal protection device (ASSE 1072)

Potable water-supplied trap seal primer valves must conform to ASSE 1018 (Section 1002.4.1.1) and waste water-supplied trap primer devices to ASSE 1044 (Section 1002.4.1.3), while barrier-type floor drain trap seal protection devices must conform to ASSE 1072 (Section 1002.4.1.4).

IPC 2018 Section 1002.4.1.1
Double check backflow prevention assemblyvsPressure vacuum breaker assembly

Per Table 608.1, the double check assembly is rated for low hazard only but protects against both backpressure and backsiphonage, while the pressure vacuum breaker assembly (ASSE 1020, CSA B64.1.2) is rated for backsiphonage only; reduced pressure principle assemblies and spill-resistant vacuum breakers are rated for high or low hazard.

IPC 2018 Section 608.1, Table 608.1
Longest length method (IFGC 402.4.1)vsBranch length method (IFGC 402.4.2)

Under the longest length method every section and branch is sized from the table row for the system's longest run, while under the branch length method each branch is sized using its own length measured from the meter (e.g., a 120 cfh branch at 50 ft sizes to 3/4 inch on the 50-ft row, where the 90-ft longest-length row would call for 1 inch).

IFGC Section 402.4.1, Longest Length Method; Table 402.4(2), Schedule 40 Metallic Pipe (natural gas, 0.5 in. w.c. drop)
Toilet travel distance in covered/open mall buildingsvsToilet travel distance in other occupancies

In covered and open mall buildings the required facilities shall be not more than one story above or below the space served and the path of travel shall not exceed 300 feet from the main entrance of the store or tenant space (Section 403.3.4), while the 500-foot limit of Section 403.3.3 applies to occupancies other than malls.

IPC 2018 Chapter 4, Section 403.3.4 (Location of Toilet Facilities in Malls)
Urinal substitution in assembly and educational occupanciesvsUrinal substitution in all other occupancies

Urinals shall not be substituted for more than 67 percent of the required water closets in assembly and educational occupancies, while in all other occupancies the limit is 50 percent.

IPC 2018 Section 424.2
Application extension (IPC 106.3.3)vsPermit extension (IPC 106.5.4)

A permit application is deemed abandoned 180 days after filing unless pursued in good faith, but the code official may grant one or more extensions of not more than 180 days each upon written request with justifiable cause, whereas permit extensions under 106.5.4 may be granted only once.

IPC 2018 Chapter 1 Scope and Administration — Section 106.3.3 Time Limitation of Application
Fixtures required to discharge through a grease interceptorvsFood waste disposer

Pot sinks, prerinse sinks and floor drains into which kettles are drained must discharge through a grease interceptor (Section 1003.3.1), while a food waste disposer shall not discharge to a grease interceptor (Section 1003.3.2).

IPC 2018 Section 1003.3.2

Key Terms

Branch interval IPC 2018 Section 202 — Branch Interval definition (Chapter 2 Definitions)
A vertical measurement of 8 feet (2438 mm) or more in developed length between the connections of horizontal branches to a drainage stack, measured down the stack from the highest horizontal branch connection (IPC 2018 Section 202).
Circuit vent IPC 2018 Section 202 — Circuit Vent definition (Chapter 2 Definitions)
A vent that connects to a horizontal drainage branch and vents two traps to not more than eight traps or trapped fixtures connected into a battery (IPC 2018 Section 202).
Grease interceptor, gravity IPC 2018 Section 202 — Grease Interceptor, Gravity definition (Chapter 2 Definitions)
A plumbing appurtenance of not less than 500 gallons (1893 L) capacity in which separation is accomplished by gravity during a retention time of not less than 30 minutes (IPC 2018 Section 202).
Backflow, low head backpressure IPC 2018 Chapter 2 — Section 202, definition of Backflow (Backpressure, low head)
A pressure less than or equal to 4.33 psi (29.88 kPa), or the pressure exerted by a 10-foot (3048 mm) column of water (IPC 2018 Section 202).
Plumbing appurtenance IPC 2018 Chapter 2 — Section 202, definitions of Plumbing Appurtenance and Plumbing Appliance
A manufactured device, prefabricated assembly or on-the-job assembly that is an adjunct to the basic piping system and plumbing fixtures, which demands no additional water supply and adds no discharge load to a fixture or to the drainage system (IPC 2018 Section 202).
Bearing plane of a footing (IPC 307.5) IPC 2018 Chapter 3 — Section 307.5 Protection of Footings
The zone that trenching parallel to footings and walls shall not extend into, whose upper boundary is a line extending downward at an angle of 45 degrees (0.79 rad) from horizontal, measured from the outside bottom edge of the footing or wall.
Pipe sleeve through a foundation wall (IPC 305.3) IPC 2018 Chapter 3 — Section 305.3 Pipes Through Foundation Walls
An alternative to a relieving arch for a pipe passing through a foundation wall; the sleeve built into the wall must be two pipe sizes greater than the pipe passing through.
Successive-section water test (IPC 312.2) IPC 2018 Chapter 3 — Section 312.2 Drainage and Vent Water Test
Testing a drainage and vent system in sections, where each section under test includes not less than the upper 10 feet of the next preceding section, so that no joint or pipe except the uppermost 10 feet of the system is tested with less than a 10-foot head of water held not less than 15 minutes.
Pressure-reducing valve (IPC 604.8.1) IPC 2018 Section 604.8.1
A building water supply valve that shall be designed to remain open to permit uninterrupted water flow in case of valve failure.
Annual permit (IPC 106.1.1 and 106.1.2) IPC 2018 Sections 106.1.1 and 106.1.2, Chapter 1 Scope and Administration
A permit the code official may issue, in place of an individual construction permit for each alteration, to a person, firm or corporation regularly employing one or more qualified tradespersons on the premises, covering alterations to an already approved system, equipment or appliance installation; the holder must keep a detailed record of alterations made under it.
Approved agency (IPC 105.3 and 105.3.2) IPC 2018 Chapter 1 — Sections 105.3 and 105.3.2 Required Testing/Testing Agency
The entity that must perform tests required by the code official where there is insufficient evidence of compliance, with such tests made at no expense to the jurisdiction (distinct from the permit holder, who makes the plumbing system tests of Sections 312/107.4).
Vent connection at base (IPC 904.4) IPC 2018 Chapter 9 Vents — Section 904.4 Vent Connection at Base
A vent stack shall connect to the base of the drainage stack at or below the lowest horizontal branch, or where connected to the building drain, downstream of the drainage stack within a distance of 10 times the diameter of the drainage stack.
Storm water trap for individual conductors (IPC 1103.3) IPC 2018 Chapter 11, Section 1103.3 (Chapter 11 Storm Drainage — Traps)
Where leaders and storm drains connect to a combined sewer, individual traps serving each conductor shall be the same size as the horizontal drain to which they are connected, with an accessible cleanout required on the building side of the trap (1103.4).
Lead free solder (IPC 605.13.6) IPC 2018 Section 605.13.6
Solder and flux used for joining water supply piping having a chemical composition equal to or less than 0.2-percent lead.
Clothes washer interceptor (IPC 1003.6) IPC 2018 Section 1003.6
An interceptor with a wire basket or similar device through which clothes washers discharge, preventing passage into the drainage system of solids 1/2 inch (12.7 mm) or larger, string, rags, buttons or other materials detrimental to the public sewage system.
Ventilated thimble (IFGC 503.7.7, Item 1) IFGC 2018 Section 503.7.7
A guard at the point a single-wall metal vent pipe passes through a combustible wall; for listed appliances with draft hoods and appliances listed for Type B gas vents it must be not less than 4 inches larger in diameter than the pipe, but not less than 2 inches larger is permitted where there is a run of not less than 6 feet of metal pipe in the open between the draft hood outlet and the thimble (6 inches applies to unlisted appliances with draft hoods, 12 inches to residential and low-heat appliances).

Formulas to Know

Gas demand in cfh from appliance input (natural gas, 1,000 Btu per cu ft)cfh = total Btuh ÷ 1,000; e.g., (50,000 + 40,000 + 100,000) ÷ 1,000 = 190 cfh at the meter; (100,000 + 200,000 + 40,000) ÷ 1,000 = 340 cfh; (40,000 + 65,000 + 30,000) ÷ 1,000 = 135 cfh; (80,000 + 40,000 + 30,000) ÷ 1,000 = 150 cfh; (65,000 + 40,000 + 50,000) ÷ 1,000 = 155 cfh
Appliance input a pipe can serve, converted from table capacityBtuh = table capacity in cfh × 1,000 Btu per cu ft; e.g., 247 cfh = 247,000 Btuh, 44 cfh = 44,000 Btuh, 117 cfh = 117,000 Btuh
Spare (or short) capacity of an installed gas pipeSpare cfh = table capacity at that length − connected demand; e.g., 170 cfh capacity − 60 cfh demand = 110 cfh spare; 137 cfh − 135 cfh = 2 cfh margin
Table row selection in Table 402.4(2) (Schedule 40 metallic, natural gas, inlet < 2 psi, 0.5 in. w.c. drop, SG 0.60)Use the next table length row at or above the actual run: 15 ft → 20-ft row; 35 ft → 40-ft row; 95 ft → 100-ft row; 110 ft → 125-ft row; 140 ft → 150-ft row
Longest length method branch/section sizingSize every section and branch from the system's longest-run row, not the branch's own length; e.g., 40,000 Btuh = 40 cfh branch, 70-ft row, 1/2 inch carries 60 cfh; 65,000 Btuh = 65 cfh branch, 40-ft row, 1/2 inch carries 81 cfh
Branch length method sizingEach branch uses its own length measured from the meter (main length to the tee + branch length); e.g., 15 ft main + 8 ft branch = 23 ft → 30-ft row; 120 cfh branch at its own 50 ft → 50-ft row, 3/4 inch (151 cfh); and the most remote outlet's length sizes the main sections feeding it (55 ft → 60-ft row; 85 ft → 90-ft row; 70 ft → 70-ft row)
Load carried by a main section downstream of a teeSection load = sum of the inputs of all outlets it serves ÷ 1,000; e.g., outlets 2–4: 40,000 + 35,000 + 100,000 = 175 cfh → 1 inch on the 70-ft row (237 cfh); outlets 2–3: 35,000 + 40,000 = 75 cfh → 1/2 inch on the 40-ft row (81 cfh); outlets 2–3: 40,000 + 50,000 = 90 cfh → 3/4 inch on the 80-ft row
Vent stack connection to the building drainMaximum distance downstream of the drainage stack = 10 × stack diameter; for a 4-inch stack, 10 × 4 in. = 40 inches
Drainage fixture units from a known gpm discharge1 gpm of flow = 2 drainage fixture units (IPC 709.3)
Required female water closets from total occupant loadDivide the total occupant load in half (Section 403.1.1), then apply the Table 403.1 ratio; worked example: restaurant with 150 total occupants → 150 ÷ 2 = 75 females ÷ (1 per 75) = 1 water closet
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