Exam Cheat Sheet · Quick Reference
South Carolina Plumber
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
80
Passing score
70%
Exam time
240 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
South Carolina State Portion 80 questions
ADA Accessibility
1 Q · 1%
Water closet location, clearance dimensions, and seat height requirementsGrab bar specifications for toilet and bathing facilities (dimensions, placement, structural strength)Accessible and ambulatory toilet compartment size and door requirementsDrinking fountain requirements for wheelchair users and standing persons (spout height, location, water flow)Shower compartment types and dimensions (transfer-type, standard roll-in, alternate roll-in)Lavatory and sink clearances, mounting heights, and knee/toe clearanceAccessible bathtub requirements (clearances, grab bars, controls, hand shower, seat dimensions)Turning space and clear floor space dimensions for accessible toilet and bathing rooms
General Plumbing Knowledge
6 Q · 8%
IPC code scope, purpose, and applicability to plumbing systemsPermits: application, issuance, expiration, and exempt workInspections and testing requirements (underground, rough-in, final, and system pressure tests)Code official authority, duties, violations, and stop work ordersKey plumbing terminology and definitions (IPC Chapter 2)General installation regulations: pipe protection, support intervals, trenching, and backfillSC 811 one-call notification requirements, excavator responsibilities, and tolerance zone rulesBasic plumbing mathematics: measurements, formulas, geometry, and unit conversions
General Plumbing Regulations
3 Q · 4%
Permit application, issuance, expiration, and exemptionsCode official authority, duties, and enforcement powersInspections and testing requirements for plumbing systemsViolations, stop work orders, and unsafe plumbing condemnationSC 811 excavator notification requirements and locate request proceduresTolerance zone requirements and hand-dig rules near underground facilitiesEmergency excavation procedures and damage reporting under SC lawPlumbing business licensing, bonding, and contractor responsibilities
Hangers and Supports (General)
2 Q · 2%
Hanger spacing intervals by pipe material (Table 308.5)Maximum horizontal and vertical support spacing requirementsApproved materials for hangers, anchors, and supports (galvanic action prevention)Structural attachment of hangers and anchors to building constructionSway bracing for horizontal drainage pipes at direction changesAnchorage and restraint of drainage piping at direction and diameter changesSupport requirements for thermal expansion tanks and manifold piping systemsDefinition and equivalence of hangers, anchors, and supports terms
Materials
2 Q · 2%
Approved pipe and fitting standards for water service and distribution systems (Table 605.3, 605.4, 605.5)Approved pipe and fitting standards for sanitary drainage, waste, and vent systems (Tables 702.1, 702.2, 702.3, 702.4)Joining methods and joint types by pipe material (solvent cement, solder, braze, heat fusion, mechanical, press-connect, push-fit)Prohibited joints and connections for water supply and drainage pipingGas piping materials — metallic pipe, tubing, CSST, and plastic pipe standards (IFGC Section 403)Lead content restrictions for water supply pipe, fittings, valves, and solderMaterial identification, third-party certification, and manufacturer markings requirementsApproved materials for vent pipe flashings and specialty fixture construction
Joints and Connections
3 Q · 4%
Joint types by pipe material (ABS, PVC, CPVC, PEX, copper, steel, cast iron)Prohibited joints and connections in water supply and sanitary drainage systemsSolvent cementing procedures and primer requirements for plastic pipeSolder and brazed joint requirements for copper pipe and tubingMechanical and press-connect joint installation requirementsJoints between dissimilar piping materials and dielectric fittingsGas piping joint and fitting requirements (threaded, brazed, welded, flared)Fitting allowances and pipe length calculations for threaded, copper, and plastic fittings
Fixtures and Equipment
3 Q · 4%
Minimum number of plumbing fixtures by occupancy typeFixture installation requirements and clearancesFixture materials and product standardsWater heater safety devices and relief valvesWater heater installation, access, and location requirementsAccessible plumbing fixtures and facilities (ICC A117.1)Faucets, shower valves, and temperature-limiting devicesGas-fired appliances and specific equipment requirements
Water Heaters
4 Q · 5%
Temperature and pressure relief valve requirements and discharge pipingSafety devices (antisiphon devices, vacuum relief valves, pan requirements)Water heater installation requirements (location, access, clearances, attic installations)Cold water supply valve and connection requirementsTemperature controls and maximum water temperature limitsGas-fired water heater listing and installation standards (ANSI Z21.10.1/CSA 4.1, IFGC compliance)Water heaters used for space heating (combination systems, mixing valve requirements)Unfired hot water storage tank insulation requirements
Water Supply and Distribution
3 Q · 4%
Backflow prevention devices and assemblies (air gaps, vacuum breakers, reduced pressure principle, double check assemblies)Cross-connection control and potable water system protectionWater service pipe materials, standards, and installation requirementsWater distribution pipe materials, fittings, joints, and connection methodsPipe sizing using water supply fixture units and pressure loss calculationsPressure regulation, water hammer arrestors, and booster systemsHot water supply system requirements including temperature limits, recirculation, and thermal expansion controlWater heater installation, safety devices, and relief valve discharge piping
Backflow Prevention
1 Q · 1%
Types of backflow (backsiphonage vs. backpressure) and hazard levels (high vs. low hazard contamination vs. pollution)Reduced pressure principle backflow prevention assemblies — application and installation requirementsVacuum breakers — atmospheric-type, pressure vacuum breaker, and spill-resistant types — installation height and use limitationsDouble check backflow prevention assemblies — application to low-hazard and fire protection systemsAir gap requirements — minimum dimensions and application per Table 608.16.1Backflow preventer device selection per Table 608.1 — matching device to degree of hazard and backflow typeSpecial connections requiring backflow protection — boilers, irrigation systems, sprinkler systems, carbonated beverage dispensers, and chemical dispensersBackflow preventer location, access, freeze protection, and relief port discharge requirements
Sanitary Drainage Systems
4 Q · 5%
Drainage fixture unit (DFU) values and system sizing tablesHorizontal drainage pipe slope requirementsCleanout placement, sizing, and access requirementsPipe materials and joint types for above-ground, underground, and building sewer applicationsSumps, ejectors, and below-grade drainage systemsTrap requirements, prohibited trap types, and trap seal protectionGrease interceptors, oil separators, and other interceptor/separator requirementsIndirect waste piping, air gaps, air breaks, and waste receptors
Cleanouts
2 Q · 2%
Required locations for cleanouts (horizontal drains, building drains, building sewers, and direction changes)Cleanout spacing intervals and measurement methodsCleanout sizing requirements relative to pipe size servedCleanout plug materials and head typesClearance requirements for cleanout accessCleanout installation arrangement and direction of cleaningCleanout equivalents (fixture traps, removable P-traps)Prohibited use of cleanout openings for fixture or piping extensions
Indirect and Special Waste
2 Q · 2%
Air gap vs. air break requirements and distinctionsWhere indirect waste connections are required (food handling, dishwashers, pools, sterilizers, humidifiers)Waste receptor types, installation requirements, and prohibited locationsIndirect waste pipe trapping requirements and length limitsStandpipe installation requirements and dimensional limitsNeutralizing and dilution devices for corrosive/chemical wastesSeparation of chemical drainage and vent systems from sanitary systems
Sanitary Venting
6 Q · 8%
Trap seal protection and maximum allowable pressure differentialVent terminal requirements and prohibited locationsVent pipe sizing using drainage fixture units and developed lengthTypes of venting methods: individual, common, wet, circuit, combination waste and vent, and waste stack ventAir admittance valves: installation, location, size, and use limitationsVent connections, grading, and vertical rise requirementsRelief vents for stacks exceeding 10 branch intervalsFrost closure and outdoor vent extension requirements
Traps and Interceptors
3 Q · 4%
Fixture trap requirements (distance limits, sizing, and prohibited trap types)Trap seal depth requirements and protection methods (primer valves, barrier devices, fixture drain connections)Grease interceptors and automatic grease removal devices (where required, sizing, and installation)Oil separators (required locations, design standards, and capacity requirements)Sand, solids, and specialty interceptors (clothes washers, bottling plants, slaughterhouses)Venting of interceptors and separators to prevent air bindingAccess and maintenance requirements for interceptors and separatorsMaterials, joints, and connections for traps, interceptors, and separators
Storm Piping Systems
2 Q · 2%
Storm drain pipe sizing using rainfall rate and roof area calculations (GPM formula)Acceptable piping materials and standards for storm drainage conductors, building storm drains, and building storm sewersRoof drain requirements, flow rates, and installation standardsSecondary (emergency) roof drains and scuppers: sizing, placement, and discharge requirementsSubsoil drain systems: pipe types, minimum diameter, backwater protection, and discharge locationsSump pits and pumping systems: pit dimensions, pump capacity, discharge piping, and valve requirementsSiphonic and controlled flow roof drain system requirements100-year hourly rainfall rates for South Carolina cities and application to storm system design
Plumbing - Developed Length
5 Q · 6%
Center-to-center vs. end-to-end pipe length calculationsFitting allowances for threaded, copper, PVC, and cast iron fittingsOffset, diagonal, rise, and run calculations using angle constants (45°, 60°, 22½°, 11¼°)Rolling offsets and true offset calculationsGrade, drop, and slope of horizontal drainage pipingDeveloped length measurement for cleanout spacing requirements (IPC Section 708)Developed length of hot water piping from source to fixture (IPC Section 607.2)Equivalent length of fittings and valves for water piping system sizing
DWV Isometric Analysis (Isometric Based)
10 Q · 12%
Fixture unit (DFU) values and drainage load calculations from isometric drawingsHorizontal and vertical drain pipe sizing using Tables 710.1(1) and 710.1(2)Pipe slope requirements for horizontal drainage pipingVent pipe sizing and developed length determination from isometric layoutsTrap-to-vent distance limits and fixture drain slope requirementsOffset pipe length calculations using 45° constants (diagonal, rise, run)Cleanout placement requirements identifiable from isometric diagramsTrap seal requirements and prohibited trap types identifiable in system layouts
Water Supply Isometric Analysis
4 Q · 5%
Water supply fixture units (WSFU) and peak demand estimationPressure loss calculations: elevation head, meter loss, tap loss, and friction lossSegmented loss method for sizing water service and distribution pipingEquivalent length of fittings and valves in pipe sizing calculationsPipe offset geometry: diagonal, rise, run, and angle constants for isometric layoutFitting allowances and end-to-end pipe length calculations for threaded, copper, and plastic pipeMinimum fixture supply pipe sizes and flow pressure requirements per IPC Table 604.3 and 604.5Water pressure requirements, pressure-reducing valves, and booster systems
Roof Drain Isometric Analysis
3 Q · 4%
Rainfall rate conversion to GPM using IPC Equation 11-1Roof drain flow rate and head-based sizing requirementsHorizontal and vertical storm drain pipe sizing using IPC Table 1106.2Vertical leader sizing using IPC Table 1106.3Secondary (emergency) roof drain and scupper sizing requirements100-year hourly rainfall rates for specific cities and geographic regionsIsometric pipe length calculations using center-to-center and end-to-end methods with offset constantsMinimum roof drain quantity requirements and controlled flow system rules
Pipe Assembly
1 Q · 1%
Fitting allowance calculations for threaded, copper, PVC, and welded pipeCenter-to-center and end-to-end pipe length measurementsPipe offset geometry using 45° and other angle constantsJoint types and connection methods by pipe materialPipe material types, weights, and schedulesDrainage piping slope and change-of-direction fitting requirementsPipe support intervals and protection requirementsGas piping materials, joint types, and installation requirements
Valves
1 Q · 1%
Full-open valve and shutoff valve placement requirements (IPC 606.1–606.2)Water pressure-reducing valves (ASSE 1003) and pressure booster systemsTemperature and pressure relief valves for water heaters (ANSI Z21.22, IPC 504)Backflow preventer valve types, hazard classification, and applicable standards (IPC Table 608.1)Gas shutoff valve location, access, and identification requirements (IFGC 409)Gas appliance shutoff valve standards and placement (IFGC Table 409.1.1)Backwater valves for sanitary drainage systems (IPC 714)Valve compatibility with piping materials and lead-content requirements (IPC 605.7)
General Fuel Knowledge
3 Q · 4%
Fuel gas types and properties (natural gas, LP-gas, manufactured gas, specific gravity, BTU content)Key IFGC definitions and terminology for fuel gas systemsIFGC scope and applicability of fuel gas code regulationsProhibited and approved appliance locations and installation requirementsCombustion air requirements and calculation methodsGas leak recognition (smell, sight, sound indicators)Appliance listing, labeling, and approval requirementsElectrical bonding and grounding requirements for gas piping systems
Natural Gas
3 Q · 4%
Gas piping materials, fittings, and approved standards (steel, copper, CSST, polyethylene)Pipe sizing methods and capacity tables (longest length, branch length, hybrid pressure methods)Allowable pressure drop and maximum operating pressure inside buildingsCombustion air requirements for gas appliances (indoor, outdoor, and combination methods)Venting systems for gas appliances (Type B, single-wall, chimneys, vent connectors, termination clearances)Gas piping installation requirements (support, identification, testing, purging, leak checks)Appliance location, clearances, and prohibited installation areasGas leak recognition and emergency response procedures
LP - Gas
3 Q · 4%
LP-gas piping system design and sizing methods (longest length, branch length, hybrid pressure)Allowable piping materials and fittings for LP-gas systems (metallic pipe, copper tubing, CSST, polyethylene plastic)LP-gas operating pressure requirements and maximum pressure limits (first-stage, second-stage, low-pressure regulators)LP-gas storage system requirements and compliance with NFPA 58Pressure testing and leak checking of LP-gas piping systemsVenting requirements for LP-gas appliances (vent types, termination, sizing)Combustion air requirements for LP-gas appliancesLP-gas system operation below -5°F and prevention of liquid condensation
Key Distinctions
Flow PressurevsStatic Pressure
Flow pressure is measured in the supply pipe near an outlet while the outlet is wide open and flowing, whereas static pressure is the pressure in the pipe when no water is moving (calculated at 0.433 psi per foot of elevation head).
International Plumbing Code 2021, Page 2-4Copper Fitting AllowancevsThreaded Fitting Allowance
Copper fitting allowance uses center-to-face minus solder cup depth with no thread-in deduction, while threaded fitting allowance requires an additional thread-in deduction.
Mathematics for Plumbers, Unit 10, Pages 56-57 (Allowances for Copper Fittings)PVC (Plastic) Fitting AllowancevsThreaded Fitting Allowance
PVC fitting allowance is measured from center to the outside shoulder of the hub cup (same process as copper, no thread-in deduction), whereas threaded fittings require a thread-in deduction step.
Mathematics for Plumbers, Unit 12, Pages 60-61 (Allowance for Plastic Fittings)Horizontal Stack Offset SizingvsVertical Stack Sizing
Horizontal stack offsets must be sized using the same criteria as building drains (Table 710.1(1)), not the stack sizing table used for vertical portions.
Ipc 2021, Section 710.1.1Individual Vent ≤40 ft Developed LengthvsIndividual Vent >40 ft Developed Length
A vent with 40 feet or less of developed length may remain at its base minimum size, but a vent exceeding 40 feet must be increased by one nominal pipe size for its entire length.
IRC P3113.1Stack Vent Sizing (Table 906.1)vsIndividual Vent Sizing (Section 906.2)
Stack vent size is selected from Table 906.1 based on stack diameter, DFU load, and developed length, while individual vent size is determined by taking half the fixture drain diameter (minimum 1¼ inch) and upsizing one nominal size if developed length exceeds 40 feet.
IPC 2021 — Table 906.1Above-Ground Drainage Pipe (Table 702.1)vsUnderground Building Drainage Pipe (Table 702.2)
Polyethylene (PE) plastic pipe is approved for underground building drainage and vent piping but is NOT approved for above-ground drainage and vent piping, whereas materials such as cast iron, ABS, and copper are approved for both.
IPC 2021, Tables 702.1 and 702.2Building Sewer Approved MaterialsvsBuilding Sewer Prohibited Materials
Vitrified clay, cast iron, concrete, and copper tubing Type K or L are approved building sewer materials, while galvanized steel pipe is not listed and is therefore not permitted.
IPC 2021, Table 702.3CPVC Solvent Cement (Primer Required, Orange)vsCPVC One-Step Solvent Cement (Yellow)
When a manufacturer requires a primer for CPVC, the solvent cement must be orange (ASTM F493); when a one-step cement is permitted, it must be yellow (ASTM F493).
IPC Section 605.14.2PVC Solvent Cement JoiningvsCPVC Solvent Cement Joining (Two-Step)
PVC joints require a purple primer (ASTM F656) and cement conforming to ASTM D2564, while CPVC two-step joints require an approved primer followed by orange cement conforming to ASTM F493.
IRC P2906.9.1.4Wet VentvsIndividual (Dry) Vent
A wet vent simultaneously carries the waste discharge of one fixture while venting one or more other fixtures, whereas an individual vent serves only the venting function and carries no fixture discharge.
Segmented Loss Method Fitting Factor (¾-in meter)vsSimplified Fitting Allowance Factor
The segmented loss method adds 50% of developed length to account for fittings/valves (equivalent length × 1.5), while the simplified sizing method for a ¾-inch meter multiplies actual pipe length by 1.2 to compensate for fitting losses.
International Plumbing Code 2021, Page E-4 (Section E103.3, Step 6)Key Terms
Individual Vent Upsizing Rule (>40 ft) IRC P3113.1
Per IPC 2021 Section 906.2, any individual vent whose developed length exceeds 40 feet must be increased by one nominal pipe size for its entire developed length.
Horizontal Stack Offset Sizing Requirement Ipc 2021, Section 710.1.1
Per IPC Section 710.1.1, horizontal stack offsets must be sized using the same criteria as building drains in accordance with Table 710.1(1).
Vent Stack Connection Distance Limit IPC Section 904.4
Per IPC Section 904.4, where a vent stack connects to the building drain, the connection must be located downstream of the drainage stack and within a distance of 10 times the diameter of the drainage stack.
Horizontal Drainage Cleanout Interval International Plumbing Code 2021, Page 7-7 (Section 708.1.1)
Per IPC Section 708.1.1, cleanouts on horizontal drainage pipes inside buildings must be installed at intervals not exceeding 100 feet, measured along the developed length.
Cleanout at Change of Direction (>45°) International Plumbing Code 2021, Page 7-7 (Section 708.1.4)
Per IPC Section 708.1.4, a cleanout must be installed wherever a horizontal drainage pipe, building drain, or building sewer has a change of horizontal direction greater than 45 degrees.
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 not be less than ¾ inch in diameter regardless of the number of fixtures served.
Hot Water Distribution Maximum Developed Length International Plumbing Code 2021, Page 6-11, Section 607.2
Per IPC Section 607.2, the developed length of hot or tempered water piping from the source to the farthest fixture requiring hot water shall not exceed 50 feet.
CPVC Threading Wall Thickness Requirement International Plumbing Code 2021, Page 6-7
Per IPC Section 605.14.3, CPVC pipe that is to be threaded must have a wall thickness of not less than Schedule 80.
Water Heater Ignition Source Elevation (Garage) International Residential Code, Page 629 (P2801.7)
Per IRC P2801.7, water heaters with an ignition source installed in a garage must have the ignition source elevated not less than 18 inches above the garage floor.
Temperature Relief Valve Sensing Element Location International Residential Code, Page 630; International Plumbing Code 2021, Page 5-2
Per IRC P2804.4 / IPC Section 504.4.1, temperature relief valves must be installed so the sensing element monitors water within the top 6 inches of the tank.
Pipe Sleeve Size Through Foundation Wall IRC P2603.4
Per IRC P2603.4, a pipe sleeve built into a foundation wall must be two nominal pipe sizes greater than the pipe passing through it.
DWV Air Test Pressure Section 312.3
Per IPC Section 312.3, drainage and vent systems shall be air-tested at a uniform gauge pressure of 5 psi held for not less than 15 minutes; plastic piping shall not be air-tested.
Flow Pressure International Plumbing Code 2021, Page 2-4
Per IPC Section 202, flow pressure is the pressure in the water supply pipe near a faucet or water outlet while that outlet is wide open and flowing.
Developed Length International Plumbing Code 2021, Page 2-3
Per IPC Section 202, developed length is the length of a pipeline measured along the centerline of the pipe and fittings, following the actual path including all fittings.
Wet Vent
A wet vent is a pipe that simultaneously carries the waste discharge of one fixture and provides the vent for one or more other fixtures, typically used for a single bathroom group.
Saddle-Type Fittings (Prohibited) International Plumbing Code 2021, Page 6-6, Section 605.9
Per IPC Section 605.9, saddle-type fittings are explicitly prohibited as joints and connections in water supply systems.
Formulas to Know
Static Pressure from Elevation Head
Pressure (psi) = Height (ft) × 0.433 psi/ftElevation Height Required for a Given Pressure
Height (ft) = Desired Pressure (psi) ÷ 0.433 psi/ftPressure Difference Between Two Fixtures (Gravity System)
ΔP (psi) = (Elevation A − Elevation B) ft × 0.433 psi/ftEquivalent Length of Run (Segmented Loss / Fitting Allowance)
Equivalent Length = Developed Length × 1.5 (adds 50% for fittings and valves)Maximum Developed Length for Water Piping (¾-in meter sizing method)
Max Developed Length = Actual pipe length × 1.2Minimum Individual Vent Size (Base)
Min Vent Diameter = max(½ × Fixture Drain Diameter, 1¼ inch)Individual Vent Size Adjustment for Long Runs
If Developed Length > 40 ft: Vent Size = Base Vent Size + one nominal pipe sizeGas Pipe Spare Capacity
Spare Capacity (cfh) = Table Pipe Capacity (cfh) − Appliance Demand (cfh)Copper Fitting Allowance
Fitting Allowance = Center-to-Face measurement − Depth of Solder Cup (no thread-in deduction)Horizontal Drainage Pipe Slope Check
Required slope: ≤2½" pipe → ¼"/ft; 3"–6" pipe → ⅛"/ft; ≥8" pipe → 1/16"/ft