South Carolina Plumber

Key Concepts

ADA accessibility for plumbing is governed by ICC A117.1-2017, referenced through the International Plumbing Code 2021. One question (1%) covers this topic, so focus on memorizing the most common dimensional requirements.

Water Closets

• Centerline of water closet: 17–18 inches from side wall
• Seat height: 17–19 inches above finish floor
• Clear floor space at water closet: 60 inches minimum width × 56 inches minimum depth (wall-hung) or 59 inches (floor-mounted)

Grab Bars — Toilet Facilities

• Side wall grab bar: 42 inches minimum length, located 12 inches max from rear wall, extending 54 inches minimum from rear wall
• Rear wall grab bar: 36 inches minimum length, centered on water closet
• Mounting…

Key Concepts

IPC Code Scope & Purpose

The International Plumbing Code (IPC) regulates the design, installation, alteration, repair, and inspection of plumbing systems. It applies to new construction and existing systems undergoing modification. The IPC does not supersede SC state amendments where adopted locally.

Permits

• Required for: New installations, alterations, repairs, and replacements of plumbing systems.
• Exempt work (typical IPC examples): Stopping leaks in drains/water/soil/waste/vent piping; clearing stoppages; repairing or replacing faucets, fixtures, or fixture trim without rerouting piping.
• Expiration: A permit expires if work does not commence within 180 days of issuance, or if work is suspended/abandoned for 180 days.
• Application: Must include description of work, location, and sufficient detail for the…

Key Concepts

Permits

• A plumbing permit is required before beginning work on most plumbing installations, alterations, or repairs.
• Exemptions typically include minor repairs such as fixing faucets, replacing fixtures (like-for-like), or clearing stoppages — but new rough-in, pipe replacement, or water heater installation generally requires a permit.
• Permits expire if work does not commence within 180 days of issuance, or if work is abandoned/suspended for 180 days.
• Permit applications must include scope of work, job address, and contractor license information.

Key Concepts

Definitions (IPC Section 202) The terms hangers, anchors, and supports are used interchangeably under the IPC. "ANCHORS. See 'Supports.'" This equivalence is directly tested.

Table 308.5 — Hanger Spacing by Pipe Material Maximum horizontal support intervals vary by pipe type. Key values to memorize:

Key Concepts

Material Identification & Third-Party Certification (IPC §303) Every pipe, fitting, trap, fixture, and device must bear the manufacturer's identification and any markings required by the applicable referenced standard (§303.1). All plumbing products required to comply with a referenced standard must be listed by a third-party certification agency (§303.4). Plastic pipe, fittings, and components must be third-party certified to NSF 14 (§303.3). Cast-iron soil pipe, fittings, and couplings must be third-party listed and labeled per §303.5.

Water Service & Distribution Pipe (IPC Tables 605.3, 605.4, 605.5) Approved materials for water service and distribution include copper tubing (Types K, L, M), CPVC, PEX, PVC (Schedule 40/80), and ductile iron. Fittings must match the pipe standard. All materials for potable…

Key Concepts

Joint Types by Pipe Material

• ABS/PVC/CPVC plastic pipe: Joined with solvent cement. CPVC requires CPVC-specific cement (not interchangeable with PVC cement). ABS requires ABS cement.
• PEX: Joined mechanically — crimp rings, clamp rings, or expansion fittings. Never solvent-cemented.
• Copper: Joined by solder (water supply), brazed joints (gas, medical gas, or high-temp), or press-connect mechanical fittings.
• Steel/Galvanized: Threaded joints standard; also welded for gas and certain systems.
• Cast iron: Hub-and-spigot with lead/oakum (legacy) or no-hub with neoprene gasket and stainless band clamps for DWV.

Prohibited Joints and Connections

Key Concepts

Minimum Fixtures by Occupancy (IPC Chapter 4, Table 403.1)

Fixture counts are based on occupancy type and occupant load. Key thresholds to know: - Assembly (A): 1 water closet per 125 males / 65 females; 1 lavatory per 200 persons - Business (B): 1 water closet per 25 (up to 50), then 1 per 50 thereafter - Mercantile (M): 1 water closet per 500 sq ft for the first 1,500 sq ft - Drinking fountains required unless food/beverage service is available; exemptions apply for small offices (<15 occupants) - Employee and public fixtures may be separate requirements — read occupancy carefully

Key Concepts

Temperature & Pressure Relief Valves (Section 504.4) - All storage water heaters operating above atmospheric pressure must have an approved, self-closing (levered) T&P relief valve conforming to ANSI Z21.22 - T&P valve must be installed in the shell of the tank, positioned to sense water in the top 6 inches (152 mm) of the tank - Relief valves cannot be used to control thermal expansion — that is a separate function

T&P Discharge Piping (Section 504.6) - Discharge pipe must be the same size as the valve outlet — never reduced - Must terminate no more than 6 inches (152 mm) above the floor, to a floor drain, or outside the building - Must not discharge into…

Key Concepts

Backflow Prevention Devices (IPC Chapter 6)

• Air Gap: The simplest and most effective backflow preventer. Must be a minimum of twice the diameter of the supply pipe but never less than 1 inch between the lowest opening of the supply and the flood level rim of the receptacle.
• Atmospheric Vacuum Breaker (AVB): Protects against backsiphonage only. Must be installed 6 inches above the highest downstream outlet and cannot be subjected to continuous pressure for more than 12 hours.
• Pressure Vacuum Breaker (PVB): Protects against backsiphonage; can be under continuous pressure. Must be installed 12 inches above the highest downstream outlet.
• Reduced Pressure Principle Assembly (RP): Highest level of mechanical protection; protects against…

Key Concepts

Types of Backflow - Backsiphonage: Backflow caused by negative pressure (siphon effect) in the supply line — the upstream pressure drops below downstream pressure. - Backpressure: Backflow caused when downstream pressure exceeds supply pressure (e.g., boilers, pumps, elevated tanks).

Hazard Levels - High hazard (contamination): Water that is unsafe to drink — toxic, biological, or chemical pollutants. Requires maximum protection (air gap or reduced pressure principle assembly). - Low hazard (pollution): Water that is aesthetically objectionable but not health-threatening. Double check valve assembly is acceptable.

Backflow Prevention Devices (IPC Section 608)

Key Concepts

Drainage Fixture Units (DFU) DFU values quantify the load each fixture places on the drainage system. Horizontal and vertical drain pipe sizing is determined by total accumulated DFUs using IPC Table 710.1(1) (horizontal) and Table 710.1(2) (vertical). Building drains and sewers are sized by Table 710.1(3). A water closet carries the highest individual DFU value (3–6 depending on type/flush rate).

Horizontal Pipe Slope (IPC Section 704) - Pipes 3 inches or smaller: minimum slope of 1/4 inch per foot (2%) - Pipes 4 inches and larger: minimum slope of 1/8 inch per foot (1%) - Minimum slope ensures self-scouring velocity (2 fps); do not over-slope small lines excessively or liquids outrun solids.

(IPC 2021, Chapter 7 — ~2 questions, 2% of exam)

Key Concepts

Required Locations (IPC 708.1)

Cleanouts are required at the following locations: - Each change of direction greater than 45° in horizontal drainage piping - At the base of each vertical stack (including waste stacks and soil stacks) - At maximum spacing intervals in horizontal runs (see spacing below) - At the junction of the building drain and building sewer, or within 10 feet downstream of the junction - At the upper end of each horizontal drain that receives a fixture connection and runs more than 5 feet

Key Concepts

Air Gap vs. Air Break (IPC 802.3.1 & 802.3.2) - Air gap: Physical unobstructed vertical space between the indirect waste pipe outlet and the flood level rim of the waste receptor — must be at least twice the effective opening of the indirect waste pipe. Highest level of protection. - Air break: The indirect waste pipe terminates below the flood level rim but above the trap seal of the waste receptor. Less protection than an air gap.

Where Indirect Waste is Required (IPC 802.1) | Application | Required Method | |---|---| | Food handling/storage/prep equipment (non-dwelling) | Air gap only (802.1.1) | | Walk-in refrigerator/freezer floor drains | Air gap (air break if backwater valve present) (802.1.2)…

(IPC 2021, Chapter 9 | 6 questions, 8% of exam)

Key Concepts

Trap Seal Protection (§901.2) The entire vent system exists for one purpose: keep any fixture trap from experiencing a pressure differential greater than 1 inch of water column (249 Pa). Every venting decision traces back to this rule.

Vent Terminal Requirements (§903) - Open roof vent: terminate ≥6 inches above the roof (unprotected) - Roof used for assembly/recreation (deck, restaurant, bar): ≥7 feet above roof (§903.1.2) - Protected terminal (covered by solar panel, architectural shroud): ≥2 inches above roof (§903.1.3) - Sidewall vent: ≥10 feet from lot line and ≥10 feet above highest adjacent grade within 10 feet horizontal (§903.1.4); cannot terminate under soffit vents -…

Key Concepts

Fixture Trap Requirements

• Every fixture must have a water seal trap. Traps must be self-cleaning and installed as close to the fixture as possible.
• Maximum trap-to-vent distance is determined by trap/drain size (per IPC Table 909.1): 2" pipe = 8 ft; 3" = 10 ft; 4" = 12 ft.
• Prohibited trap types: S-traps, bell traps, crown-vented traps, and any trap that depends on moving parts to maintain the seal are not permitted.
• Trap size must match the fixture drain size and shall not be larger than the drainpipe it connects to.

Key Concepts

Scope & Disposal (IPC §1101) - Storm water must drain to an approved place of disposal — it cannot be drained into sewage-only sewers (§1101.3). - For 1- and 2-family dwellings, discharge onto flat surfaces (streets, lawns) is permitted if water flows away from the building. - Pipe size cannot be reduced in the direction of flow (§1101.5). - Cleanouts required on storm systems per sanitary drain rules; backwater valves required per §714 standards (§1101.8–1101.9).

Piping Materials - Inside storm conductors (above ground): Must conform to Table 702.1 (same as sanitary above-ground). - Underground building storm drain: Table 702.2. - Building storm sewer pipe (§1102.4): Acceptable materials include ABS, cast iron, concrete, copper (Type K/L/M/DWV), PE, PP,…

Key Concepts

Developed length is the total length of pipe measured along the centerline, including all bends and offsets, from one point to another. It is not straight-line (direct) distance.

Center-to-center vs. end-to-end: Pipe is drawn on blueprints using centerlines. You measure center-to-center in the field or from drawings, then subtract fitting allowances from both ends to get the end-to-end (cut) length. - End-to-end = Center-to-center − (Fitting Allowance × 2) - Fitting allowance = center-to-face dimension + thread engagement (for threaded pipe)

Fitting allowances vary by joint type: - Threaded: Allowance = center-to-face of fitting + thread-in engagement (threads are tapered; hand-tight is 2½–3 turns) - Copper (solder): Allowance = depth of cup/socket - PVC (solvent weld): Allowance…

Key Concepts

DFU (Drainage Fixture Unit) Values are assigned loads used to size drain, waste, and vent piping. Common values to memorize: - Lavatory: 1 DFU - Bathtub/shower: 2 DFU - Water closet (private): 3 DFU; (public flushometer): 6 DFU - Kitchen sink: 2 DFU - Floor drain: 2 DFU - Clothes washer standpipe: 2 DFU

Table 710.1(1) – Horizontal Drains: Used to size building drains and horizontal branches based on total DFU load and slope. Pipe capacity increases with slope — steeper slope = higher DFU capacity for same pipe diameter.

South Carolina Plumber Licensing Exam — 5% of Exam (4 Questions)

Key Concepts

Water Supply Fixture Units (WSFU): Each fixture is assigned a demand weight in WSFUs. The total WSFU load on a system is converted to peak flow (GPM) using a Hunter's Curve or equivalent demand table. Never add WSFUs and GPM directly — convert first.

Pressure Budget (Available Pressure): The static pressure at the meter must cover all losses to deliver minimum residual pressure at the highest/most remote fixture.

Available Pressure = Static Supply Pressure − Elevation Loss − Meter Loss − Tap/Service Loss − Friction Loss (pipe + fittings)

Key Concepts

Rainfall Rate Conversion (IPC Equation 11-1) Convert inches-per-hour rainfall to GPM using:

GPM = (Rainfall rate, in/hr × Drainage area, ft²) ÷ 96.23

This is the foundational formula for all storm drain sizing. The constant 96.23 converts the units correctly. Do not confuse drainage area (horizontal projected area) with roof surface area on a sloped roof.

Roof Drain Sizing (Head-Based) Roof drain flow capacity is rated at a specific head (depth of water above the drain). Standard roof drains are typically sized at 2-inch head. Higher head = more flow capacity. Always verify the manufacturer's flow rate at the specified head before sizing.

Key Concepts

Fitting Allowance (FA): The distance a pipe thread or pipe end enters a fitting socket. You must subtract the fitting allowance from the face-to-face measurement to get the correct cut length of pipe.

Center-to-Center (C-to-C) vs. End-to-End: C-to-C is the measurement between the centerlines of two fittings. To find the actual pipe cut length (end-to-end), subtract the fitting allowances for both fittings from the C-to-C dimension.

Key Formula:

Cut Length = C-to-C − FA₁ − FA₂

Joint Types by Material: - Threaded (black iron/galvanized): Tapered NPT threads; pipe screws into fitting - Copper: Soldered (sweat) joints; pipe slides into fitting socket - PVC/CPVC: Solvent-cement joints; chemical fusion bonds pipe into socket - Welded steel: Butt-weld or…

Key Concepts

Full-Open & Shutoff Valve Placement (IPC 606.1–606.2) Every water supply system must have a shutoff valve near the point of entry into the building. Shutoff valves are required on the supply to every appliance, water heater, fixture, and equipment. Full-open valves (gate valves or ball valves) must be used where full flow is required — they cannot restrict flow when open.

Water Pressure-Reducing Valves (ASSE 1003) Required when incoming water pressure exceeds 80 psi. The PRV must be installed with a strainer and must be accessible for service. A pressure gauge is recommended downstream. Pressure booster systems are used when supply pressure is insufficient to serve upper floors — these require a pressure tank and controls to…

South Carolina Plumber Licensing Exam | IFGC 2021 | 3 Questions (4%)

Key Concepts

Fuel Gas Types and Properties

• Natural gas: Lighter than air (specific gravity ~0.6), rises and dissipates. Primary component is methane. BTU content: ~1,000 BTU/cubic foot.
• LP-gas (propane): Heavier than air (specific gravity ~1.5), sinks and pools in low areas. BTU content: ~2,500 BTU/cubic foot for propane. Critical safety distinction — LP collects in basements and pits.
• Manufactured gas: Older coal-derived gas, lower BTU content (~500 BTU/cubic foot). Largely obsolete but may appear in definitions.
• Specific gravity is measured relative to air (air = 1.0). Values below 1.0 rise; values above 1.0 sink.

Key Concepts

Gas Piping Materials & Standards - Steel pipe (black or galvanized): Most common for interior gas piping; Schedule 40 minimum; threaded joints with approved compounds (PTFE tape or pipe dope rated for gas). - Copper tubing: Allowed only where gas does not contain more than 0.3 grains of hydrogen sulfide per 100 standard cubic feet. Types K and L are approved; flared or brazed fittings only — no soldered joints. - CSST (Corrugated Stainless Steel Tubing): Must be installed per manufacturer's listing and bonded/grounded per local requirements (lightning protection). Requires mechanical protection in high-traffic areas. - Polyethylene (PE): Approved for underground exterior use only — never inside buildings or above ground. Must be yellow-coded and installed at…

Key Concepts

Scope & Operating Pressure Limits (IFGC §101.2.2)

• The IFGC covers LP-gas piping systems with operating pressures of 20 psig or less
• Higher-pressure LP-gas distribution is governed by NFPA 58 (Liquefied Petroleum Gas Code)

Allowable Piping Materials

• Metallic pipe: Schedule 40 black steel or wrought iron; galvanized steel is acceptable for most applications
• Copper tubing: Types K and L are permitted for LP-gas; NOT permitted if LP-gas contains more than 0.3 grains of hydrogen sulfide per 100 scf
• CSST (Corrugated Stainless Steel Tubing): Must be listed and installed per manufacturer instructions; requires bonding
• Polyethylene (PE) plastic pipe: Permitted underground only; must be listed for LP-gas service; never used above grade…