Exam Cheat Sheet · Quick Reference

South Carolina Residential Plumbing

South Carolina  ·  PSI Services Contractor

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
65
Passing score
68%
Exam time
180 min
Administered by
PSI Services Contractor
Format
Reference materials allowed

South Carolina State Portion 65 questions

General Plumbing Knowledge and Regulations 15 Q · 23%
Repair faucetsDetermine head pressureSolder pipe jointsSolvent weld pipe jointsCalculate area and volumeCalculate water supply friction lossEstimate job costsCut notches and bore holes in structural membersInstall firestoppingFabricate pipe offsetsTest systemsDefine plumbing terms +1 more
Piping, Valves, and Controls 6 Q · 9%
Install PVC piping and connectionsInstall CPVC piping and connectionsInstall galvanized piping and connectionsInstall copper tubing and connectionsInstall copper piping and connectionsInstall underground piping and connectionsInstall valves and controls
Fixtures and Equipment 4 Q · 6%
Identify minimum plumbing needs for structures/facilitiesInstall fixtures and associated equipmentUnderstand requirements for specific fixturesMinimum number of required plumbing fixtures by occupancy typeFixture installation requirements and clearancesFixture material standards and quality requirementsFaucets and fixture fittings including shower valve temperature limitsWater closet and urinal requirements and flushing devicesSpecific fixture requirements for bathtubs, showers, sinks, and lavatoriesAccessible plumbing fixture requirements per ICC A117.1Separate toilet facilities, signage, and toilet room location requirements
Water Supply 4 Q · 6%
Install water supply and distribution linesBackflow prevention devices and assemblies (types, applications, and standards)Potable water system protection and cross-connection controlWater supply system design criteria (pressure, flow rates, and fixture units)Pipe materials, joints, and connections for water service and distributionNonpotable water system identification and labeling requirementsValves, shutoff requirements, and pressure regulationWater hammer arrestors and thermal expansion controlDwelling unit fire sprinkler system requirements and pipe sizing
Drain, Waste and Vent and Sewers 17 Q · 26%
Design and install DWV systemsInstall building sewersInstall sewer and drain cleanoutsInstall sewage ejector and sump pumpsInstall trapsInstall roof drainsDrainage fixture unit (DFU) values and system sizing using Tables 709.1 and 710.1Slope and installation requirements for horizontal drainage pipingApproved pipe materials for above-ground, underground, and building sewer applicationsCleanout requirements including location, spacing, size, and accessVent system types and installation including individual, common, wet, circuit, and air admittance valvesTrap requirements including seal depth, prohibited trap types, and trap seal protection +2 more
Isometric Analysis 9 Q · 14%
Obtain information from isometric drawings
Safety 4 Q · 6%
Understand Responsibility for Providing Personal Protective EquipmentExcavate SafelyProvide Employees Protection in Trenches and ExcavationsEnsure Safety Training is Conducted when NeededEnsure Adequate Ventilation is Available for EmployeesEnsure First Aid Kit is Available per RequirementsEnsure Personal Protective Equipment is Used CorrectlyInstall Signs, Signals, and Barricades as RequiredUse All Tools and Equipment in Accordance with RequirementsUtilize Ladders in Accordance with RequirementsFollow Requirements for Work Around Toxic MaterialsMaintain Material Safety Data Sheets (MSDS) +1 more
Specialty Applications 6 Q · 9%
Install Backflow PreventionInstall water heaters, hot water storage tanks, and tankless coilsDiagnose and repair electric water heatersInstall and connect gas appliances and equipmentInstall water conditioning and filtration systems

Key Distinctions

Flow pressurevsStatic pressure (head)

Flow pressure is the pressure in the supply pipe near the faucet/outlet while it is wide open and flowing, whereas static pressure is a function of vertical elevation only (computed at 0.433 psi per foot of head).

IPC 2021 Page 2-4
Circuit-vented branchvsWet vent

A circuit vent is a single vent serving multiple fixtures (a battery) connected along a horizontal branch drain, while a wet vent is a pipe that vents one or more fixtures while also carrying the discharge of another fixture (classically a single bathroom group).

IRC 2018 Appendix N, Figure N7
Hot water boiler gaugesvsSteam boiler gauges

Section M2002.2 requires a hot water boiler to have a pressure gauge and a temperature gauge (or combination gauge), while Section M2002.3 requires a steam boiler to have a water-gauge glass and a pressure gauge.

IRC 2018 Sections M2002.2 and M2002.3
DWV water test (rough-in)vsBuilding sewer water test

The DWV section is filled to not less than 5 feet of water above the highest fitting connection, while the building sewer is plugged at the public sewer and pressurized to not less than a 10-foot head of water; both are held not less than 15 minutes.

IRC 2018 Page 617
Stack offset 45 degrees or less from verticalvsStack offset more than 45 degrees from vertical above the lowest branch

An offset of 45 degrees or less from vertical is sized as a straight vertical drain, while an offset of more than 45 degrees above the lowest horizontal branch is sized as a building drain based on accumulated fixture units.

IRC 2018 Section P3006.1
Short sweep (horizontal to horizontal)vsSanitary tee

Per IPC Table 706.3 a short sweep (or long sweep) is permitted for horizontal-to-horizontal changes of direction, while a sanitary tee is only permitted for horizontal-to-vertical connections.

IPC 2021 Table 706.3
Sweep fittingvsBend/elbow

A sweep is a drainage fitting that changes direction with a longer turning radius than a bend, producing a less turbulent flow pattern.

IRC 2018 Section R202, Definitions
Copper Type K or L for building sewervsCopper Type M or DWV

Only Type K or L copper/copper-alloy tubing is listed for building sewer pipe; Types M and DWV are not approved for building sewer, though they are permitted for above-ground and underground building drainage.

IRC 2018 Page 664; International Plumbing Code, Page 7-2
CPVC horizontal support spacing (1 inch and smaller)vsPVC horizontal support spacing

CPVC pipe or tubing 1 inch and smaller requires horizontal support at intervals not exceeding 3 feet, while PVC pipe requires horizontal support not exceeding 4 feet.

IRC 2018 Page 621; International Plumbing Code, Page 3-4
Vent size from half the fixture drainvs1-1/4 inch absolute minimum vent size

An individual vent is based on one-half the fixture drain diameter (e.g., half of a 3-inch drain = 1-1/2 inch), but the vent can never be smaller than 1-1/4 inch, so the 1-1/4 inch minimum governs for 1-1/2 inch and 2 inch fixture drains.

IPC 2021 Section 906.2
Trap arm limit for a 2-inch trapvsTrap arm limit for a 1-1/2 inch trap

Per IPC Table 909.1 a 2-inch trap is limited to 8 feet from weir to vent and a 1-1/2 inch trap to 6 feet, while a water closet is a self-siphoning fixture whose trap-to-vent distance is not limited.

IPC 2021 Table 909.1
Sizing factor 1.2 (Appendix E104.1 method)vsAdd 50 percent of developed length (segmented loss method)

In the E104.1 sizing method the actual pipe length to the most remote fixture is multiplied by 1.2 for fitting losses, while the segmented loss method's rule of thumb adds 50 percent of the developed length (length x 1.5) when fitting sizes are not yet known.

IPC 2021 Page E-19 (Section E104.1, Item 3)
Multiple-bath group d.f.u. valuesvsAdding individual fixture d.f.u. values

Multiple-bath group values (e.g., 9 d.f.u. for 2.5 baths) account for the probability of simultaneous use and are lower than the sum of the individual fixture values.

IRC 2018 Table P3004.1

Key Terms

Flow pressure IPC 2021 Page 2-4
The pressure in the water supply pipe near the faucet or water outlet while that faucet or outlet is wide open and flowing.
Faucet IPC 2021 Page 2-4
A valve end of a water pipe through which water is drawn from or held within the pipe.
Effective opening IPC 2021 Page 2-3
The minimum cross-sectional area at the point of water supply discharge expressed as the diameter of a circle (or equivalent-area circle); for faucets and similar fittings it is measured at the smallest orifice in the fitting body or supply piping to the fitting.
Developed length IPC 2021 Page 2-3
The length of a pipeline measured along the centerline of the pipe and fittings, following the actual pipe path rather than straight-line distance.
Branch interval IRC 2018 Section R202, Definitions
A vertical measurement of distance of 8 feet 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.
Offset IRC 2018 Section R202, Definition of 'Offset'
A combination of fittings that makes two changes in direction, bringing one section of pipe out of line and into a line parallel with the other section.
Sweep IRC 2018 Section R202, Definitions
A drainage fitting that provides a change in direction with a longer turning radius than a bend, giving a less turbulent flow pattern.
Drainage fixture unit (d.f.u.) IRC 2018 Section P3004.1, Table P3004.1
A numerical factor representing the probable discharge from a fixture, used to compute the hydraulic load on DWV piping from the values in Table P3004.1.
Vent stack IPC 2021 Section 202
A separate vertical vent pipe installed to circulate air through the drainage system, connecting near the base of the soil stack and rejoining the stack vent above the highest fixture.
Crown vent rule IPC 2021 Section 909.3
A vent shall not be installed within two pipe diameters of the trap weir (3 inches for a 1-1/2 inch trap, 4 inches for a 2-inch trap); closer connections are prohibited crown vents.
Building trap IRC 2018 Section P3201.4
A trap installed on the main building drain; building traps are prohibited.
Lead-free solder IPC 2021 Section 605.12.3
Solder and flux used for joining water supply piping having a chemical composition equal to or less than 0.2-percent lead.
Exempt work (permits) IPC 2021 Page 1-4
Clearing stoppages or repairing leaks in pipes, valves or fixtures, and removal and reinstallation of water closets, provided the work does not involve replacement or rearrangement of valves, pipes or fixtures.
Abandoned permit application IPC 2021 Page 1-4
An application for a permit is deemed abandoned 180 days after filing unless pursued in good faith or a permit has been issued; the code official may grant extensions not exceeding 180 days each.
Pipe sleeve (foundation wall penetration) IRC 2018 Page 620; International Plumbing Code, Page 3-2
A sleeve built into a foundation wall (alternative to a relieving arch) that must be two pipe sizes greater than the pipe passing through the wall.
Hose connection vacuum breaker IRC Section P2902.4.3
The backflow protection required on sillcocks, hose bibbs, wall hydrants and other hose-connection openings, which may be atmospheric-type, pressure-type, a pressure vacuum-breaker assembly, or a permanently attached hose connection vacuum breaker.
Trough urinal IPC 2021 Section 401.2
A urinal type that is prohibited by IPC Section 401.2 regardless of compliance with other standards.

Formulas to Know

Static pressure from head (and head from pressure)psi = height (ft) x 0.433 psi/ft; height (ft) = psi / 0.433 (e.g., 14 ft x 0.433 = 6.06 psi; 30 / 0.433 = 69.3 ft; 60 x 0.433 = 25.98 ~ 26 psi)
Total fall in a graded horizontal drainFall = run (ft) x grade (in/ft); e.g., 32 ft x 1/4 in/ft = 8 in; 48 ft x 1/4 in/ft = 12 in = 1.00 ft; add runs for total (32 ft x 1/4 + 24 ft x 1/8 = 11 in = 0.92 ft)
Grade expressed as percent slopePercent slope = (rise in inches per foot / 12 in per foot) x 100; 1/4 in per ft = (0.25/12) x 100 = 2.08%
Downstream invert elevationDownstream invert = upstream invert - total fall; 100.00' - (48 ft x 1/4 in/ft = 1.00 ft) = 99.00'
Cut length of threaded pipeCut length = center-to-center - (takeoff at each fitting) + (thread engagement at each end); 42 - (2 x 2-1/4) + (2 x 1/2) = 38-1/2 in (two 2-in elbow takeoffs = 4 in deducted; two 1/2-in engagements = 1 in added)
Cut length of sweat/soldered copper segmentCut length = center-to-center - 1/2 in per fitting end; 24 - (2 x 1/2) = 23.00 in and 18 - (2 x 1/2) = 17.00 in (total 40.00 in)
Simple offset travel and run from setTravel = set x constant (45 deg = 1.414, 22-1/2 deg = 2.613, 60 deg = 1.155); 45 deg run = set x 1.000 (run equals set); e.g., 10 x 2.613 = 26-1/8 in; 20 x 2.613 = 52-1/4 in
Rolling offset true offset and travelTrue offset = square root of (set^2 + roll^2) = sqrt(12^2 + 9^2) = 15.0 in; then travel = true offset x fitting constant (45 deg: 15.0 x 1.414 = 21.2 in; 60 deg: 15.0 x 1.155 = 17.3 in)
Minimum individual vent sizeVent size = 1/2 the fixture drain diameter, but never less than 1-1/4 in; if vent developed length exceeds 40 ft, increase one nominal size for the entire developed length (e.g., 1-1/2 in drain, 44 ft run -> 1-1/2 in vent)
Water pipe sizing length adjustments for fittingsSegmented loss method: equivalent length = developed length x 1.5 (add 50%), e.g., 225 ft x 1.5 = 338 ft; E104.1 method: maximum developed length = actual length to most remote fixture x 1.2; threaded fittings use double the table equivalent-length allowances
Start free practice Full study guide