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
Flow pressure is measured while a faucet or outlet is wide open and flowing, whereas static pressure is measured when no water is moving in the system.
International Plumbing Code 2021, Page 2-4DWV Water Test (5-ft head)vsBuilding Sewer Water Test (10-ft head)
A DWV rough-in water test requires water filled to at least 5 feet above the highest fitting connection, while a building sewer water test requires pressurizing to not less than a 10-foot head of water.
International Residential Code, Page 617Hot Water Boiler GaugesvsSteam Boiler Gauges
A hot water boiler requires a pressure gauge and a temperature gauge (or combination), while a steam boiler requires a water-gauge glass and a pressure gauge.
Sections M2002.2 and M2002.3PVC Pipe Horizontal Support SpacingvsCPVC Pipe Horizontal Support Spacing
PVC pipe requires horizontal supports at maximum 4-foot intervals, whereas CPVC pipe or tubing 1 inch and smaller requires horizontal supports at maximum 3-foot intervals.
International Residential Code, Page 621; International Plumbing Code, Page 3-4Copper Type K or L (Building Sewer)vsCopper Type M or DWV (Building Sewer)
Only Type K or L copper tubing is permitted for underground building sewer applications; Types M and DWV are not listed as approved for building sewer use.
International Residential Code, Page 664; International Plumbing Code, Page 7-2Mechanical JointvsSolvent-Cemented Joint
A mechanical joint connects pipes by compression along the centerline without screwing, soldering, or cementing, while a solvent-cemented joint chemically bonds pipe and fitting surfaces using wet cement.
International Plumbing Code 2021, Page 2-5Vertical Drain Offset ≤ 45 DegreesvsVertical Drain Offset > 45 Degrees
A stack offset of 45 degrees or less from vertical is sized as a straight vertical drain, while an offset greater than 45 degrees above the lowest branch must be sized as a building drain.
International Residential Code, Page 671 (Section P3006.1)Streamlined Soldered / Recessed Threaded Fittings (Equivalent Length)vsStandard Threaded Fittings (Equivalent Length)
Equivalent length allowances from the table apply directly to streamlined soldered and recessed threaded fittings, but must be doubled when standard threaded fittings are used instead.
International Residential Code, Page 911; International Plumbing Code, Page E-12Segmented Loss Method Fitting Allowance (50% rule)vsAccepted Sizing Method Fitting Factor (1.2 multiplier)
The segmented loss method approximates fitting losses by adding 50% of the developed length, while the accepted sizing method for a 3/4-inch meter multiplies the actual pipe length by 1.2 to compensate for fittings.
International Plumbing Code 2021, Page E-4 (Section E103.3, Step 6)Galvanized Steel Pipe (Underground)vsGalvanized Steel Pipe (Above Ground)
Galvanized steel pipe is prohibited underground and must be maintained not less than 6 inches above ground when used in a sanitary drainage system.
International Residential Code, Page 663Permit-Required Plumbing WorkvsPermit-Exempt Plumbing Work
Most new installations, replacements, or rearrangements of pipes, valves, or fixtures require a permit, while repairing leaks or clearing stoppages without replacing or rearranging valves, pipes, or fixtures is exempt from permit requirements.
International Plumbing Code 2021, Page 1-4Short Sweep (Horizontal-to-Horizontal)vsSanitary Tee (Horizontal-to-Vertical)
A short sweep is the acceptable fitting for horizontal-to-horizontal direction changes in drainage, while a sanitary tee is only permitted for horizontal-to-vertical connections.
International Plumbing Code 2021, Page 7-7 (Table 706.3)Key Terms
Developed Length International Plumbing Code 2021, Page 2-3
The length of a pipeline measured along the centerline of the pipe and fittings, following the actual path including all fittings rather than straight-line distance (IPC Section 202).
Effective Opening International Plumbing Code 2021, Page 2-3
The minimum cross-sectional area at the point of water supply discharge, measured or expressed in terms of the diameter of a circle or equivalent (IPC Section 202).
Flow Pressure International Plumbing Code 2021, Page 2-4
The pressure in the water supply pipe near a faucet or water outlet while that outlet is wide open and flowing (IPC Section 202).
Mechanical Joint International Plumbing Code 2021, Page 2-5
A pipe connection that is not screwed, caulked, threaded, soldered, solvent cemented, brazed, welded, or heat fused, but instead uses compression applied along the centerline (IPC Section 202).
Drainage Fixture Unit (d.f.u.) International Residential Code, Page 667-668 (Section P3004.1, Table P3004.1)
A numerical factor representing the probable hydraulic discharge load of a plumbing fixture used to compute the load on a DWV system (IRC P3004.1).
Rough-In International Residential Code, Page 23 (Section R202, Definitions)
The installation of all parts of the plumbing system—DWV, water supply, and built-in fixture supports—that must be completed prior to the installation of fixtures (IRC Section R202).
Water Pressure-Reducing Valve (PRV) International Plumbing Code 2021, Page 6-3 (Section 604.8)
An approved device required by IPC Section 604.8 whenever building water pressure exceeds 80 psi static, installed to protect piping and fixtures from excess pressure.
Permit Abandonment (180 Days) International Plumbing Code 2021, Page 1-4
Per IPC Section 106.3.2, a plumbing permit application is deemed abandoned 180 days after filing if not pursued in good faith or converted to an issued permit.
Cleanout Interval (Horizontal Drainage) International Plumbing Code 2021, Page 7-7 (Section 708.1.1)
Per IPC Section 708.1.1, cleanouts on horizontal drainage piping inside buildings must be spaced no more than 100 feet apart, measured along the developed length.
Minimum Water Service Pipe Size International Plumbing Code 2021, Page 6-2 (Section 603.1)
Per IPC Section 603.1, the water service pipe entering a residential structure shall be not less than 3/4 inch in diameter regardless of the number of fixtures served.
Minimum Slope for 4-Inch Horizontal Drain International Plumbing Code 2021, Page 7-3 (Table 704.1)
Per IPC Table 704.1, horizontal drainage pipe sized 3 to 6 inches must slope not less than 1/8 inch per foot toward the point of disposal.
Lead-Free Solder (Water Supply) International Plumbing Code 2021, Page 6-7 (Section 605.12.3)
Per IPC Section 605.12.3, solder used on water supply piping must have a chemical composition of 0.2-percent lead or less and be used with noncorrosive, nontoxic flux.
Pipe Sleeve Through Foundation Wall International Residential Code, Page 620; International Plumbing Code, Page 3-2
Per IRC P2603.4 and IPC 305.3, a sleeve built into a foundation wall for pipe passage must be two pipe sizes greater than the pipe passing through it.
Steel Shield Plates (Pipe Protection) International Residential Code, Page 619; International Plumbing Code, Page 3-2
Per IRC P2603.2.1 and IPC 305.6, piping closer than 1-1/2 inches from the edge of a framing member must be protected by steel shield plates not less than No. 16 gage (0.0575 inch) thick.
Shower Liner Test (2-Inch Water Depth) International Residential Code, Page 618
Per IRC P2503.6, an on-site built-up shower liner must be filled with potable water to a depth of not less than 2 inches at the threshold and retained for at least 15 minutes without leakage.
Circuit-Vented Branch International Residential Code, Appendix N, Figure N7, Page 898
A venting arrangement in which a single vent serves multiple fixtures connected along a horizontal branch drain, rather than providing an individual vent for each fixture (IRC Appendix N, Figure N7).
Formulas to Know
Static Pressure Loss / Gain Due to Elevation
Pressure (psi) = Elevation change (ft) × 0.433 psi/ftHeight Required for a Given Static Pressure
Height (ft) = Desired pressure (psi) ÷ 0.433 psi/ftSegmented Loss Method — Total Equivalent Length (Fitting Allowance)
Total equivalent length = Developed length × 1.50Accepted Sizing Method — Maximum Developed Length with Fitting Factor
Maximum developed length = Actual pipe length (ft) × 1.2Horizontal Drain Slope — Drop Over a Run
Drop (in) = Pipe length (ft) × slope (in/ft) [e.g., 4-in pipe: slope = 1/8 in/ft]Available Pressure for Pipe Sizing (after deductions)
Available pressure = Supply pressure − elevation loss − meter loss − equipment losses (PRV, softener, backflow device, etc.)Vent Pipe Size Increase Threshold
If developed length of vent > 40 ft → increase vent pipe by one nominal pipe size for entire length