Exam Cheat Sheet · Quick Reference

Idaho Plumbing Specialty Appliance Journeyman Exam

Idaho  ·  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
50
Passing score
75%
Exam time
150 min
Administered by
PSI Services Contractor
Format
Reference materials allowed

Idaho State Portion 50 questions

2017 Idaho State Plumbing Code Chapter 1 7 Q · 14%
Scope, purpose, and applicability of the codeAuthority Having Jurisdiction (AHJ) duties, powers, and liabilityPermit requirements and exempt workPermit application process and construction documentsPermit issuance, validity, expiration, and revocationInspection types and procedures (underground, rough-in, final)Testing of plumbing systems and approval certificationViolations, penalties, stop orders, and Board of Appeals
2017 Idaho State Plumbing Code Chapter 2 6 Q · 12%
Drainage and venting system terminology (drain, waste pipe, soil pipe, stack, vent stack, branch, riser, building drain, building sewer)Backflow and cross-connection terminology (backflow, backsiphonage, backpressure, backflow preventer, air gap, air break, cross-connection, critical level)Water supply and distribution terminology (potable water, building supply, water distribution pipe, fixture branch, fixture supply, riser, water main)Plumbing fixture and appurtenance definitions (plumbing fixture, plumbing appliance, plumbing appurtenance, fixture unit, bathroom group, battery of fixtures)Trap and trap-related terminology (trap, trap seal, trap arm, trap primer, crown weir, top dip, individual vent, continuous vent)Fuel gas and venting system terminology (fuel gas, gas piping, chimney classifications, appliance heat categories, vent types B/BW/L, fuel gas venting system)Grease interceptor and special waste terminology (grease interceptor, gravity grease interceptor, hydromechanical grease interceptor, FOG disposal system, grease removal device, interceptor/clarifier)Alternate water source and gray water terminology (gray water, reclaimed water, rainwater catchment system, alternate water source, mulch basin, subsoil/subsurface irrigation field)
2017 Idaho State Plumbing Code Chapter 3 7 Q · 14%
Minimum standards for materials, listing, labeling, and manufacturer marking requirementsAlternate materials and methods of construction equivalency and AHJ approval processAlternative engineered design requirements, documentation, and permit applicationProtection of piping from breakage, corrosion, freezing, fire-resistant construction, and UV exposureHangers, supports, and pipe support intervals by material type (Table 313.3 and Table 313.6)Trenching, excavation, backfill, and thermoplastic pipe bedding requirementsProhibited fittings, prohibited practices, and prohibited drainage/vent piping connectionsTest gauge specifications and pressure testing incrementation requirements
2017 Idaho State Plumbing Code Chapter 5 20 Q · 40%
Water heater permits, inspections, and approval requirementsWater heater location requirements (bedrooms, bathrooms, garages, attics, roofs)Temperature, pressure, and vacuum relief devices (TPR valves) and safety shutoff devicesCombustion air requirements (indoor, outdoor, mechanical, and combination methods)Venting system types and selection (Type B, B-W, L vents, single-wall metal pipe, chimneys)Vent and chimney sizing for Category I appliances (single and multiple appliance tables)Vent connector requirements (materials, clearances, slope, length, joints)Seismic strapping, drainage pans, ground support, and physical installation requirements
2017 Idaho State Plumbing Code Chapter 6 5 Q · 10%
Backflow prevention devices, assemblies, and methods (air gap, AVB, PVB, SVB, DC, RP) selection and installation requirementsCross-connection control and prohibited connections to potable water systemsWater supply piping materials, pipe types, and lead content requirementsPipe joining methods by material type (soldered, brazed, flared, mechanical, solvent cement, heat-fusion)Water pressure requirements, pressure regulators, expansion tanks, and relief valve discharge pipingSizing potable water supply systems using fixture units, Table 610.3, and Table 610.4Valves — types, placement, and shutoff requirements for water supply systemsResidential fire sprinkler system installation, sprinkler placement, piping design, and inspection
2017 Idaho State Plumbing Code Chapter 12 5 Q · 10%
Acceptable piping materials and joining methods (metallic pipe, tubing, CSST, plastic pipe)Gas piping system design and sizing methods (longest length, branch length, hybrid pressure)Underground and aboveground gas piping installation requirementsInspection and pressure testing requirements for gas piping systemsGas pressure regulators: installation, venting, and overpressure protectionAppliance connections, shutoff valves, and sediment trapsElectrical bonding and grounding of gas piping systemsPurging requirements for gas piping systems

Key Distinctions

AccessiblevsReadily Accessible

"Accessible" means access may first require removing an access panel, door, or similar obstruction, while "Readily Accessible" means direct access without removing any panel, door, or obstruction.

ISPC 2017 Section 203.0
Contamination (High Hazard)vsPollution (Low Hazard)

Contamination is an impairment of potable water quality creating an actual hazard to public health through poisoning or spread of disease (High Hazard), while pollution impairs quality only to a degree that adversely and unreasonably affects aesthetic qualities without creating a health hazard (Low Hazard).

ISPC 2017 Section 218.0 (Pollution)
Brazed jointvsSoldered joint

A brazed joint uses alloys melting above 840°F (449°C) but below the melting point of the parts joined, whereas a soldered joint uses metallic mixtures or alloys melting at temperatures up to and including 840°F (449°C).

ISPC 2017 Section 212.0 - Joint, Brazed
Permit application expiration (Sec. 104.3.3)vsPermit expiration for work not commenced (Sec. 104.4.3)

An application for which no permit is issued expires by limitation 180 days after the application date, while an issued permit becomes null and void if the authorized work is not commenced within 180 days from the date of the permit (requiring a new permit).

ISPC 2017 Section 104.3.3
Test gauge for tests of 10 psi or lessvsTest gauge for tests over 10 psi up to 100 psi

Tests of 10 psi or less require gauges with 0.10 psi incrementation or less; tests exceeding 10 psi but not more than 100 psi require gauges of 1 psi incrementation or less — in both cases the gauge range may not exceed twice the test pressure.

ISPC 2017 Sections 318.3 and 318.5
Thimble 4 inches larger than pipevsThimble 2 inches larger than pipe

For listed appliances with draft hoods vented with single-wall metal pipe through a combustible wall, the ventilated metal thimble must be not less than 4 inches larger in diameter than the pipe; the 2-inch allowance applies only where there is a run of not less than 6 feet of metal pipe between the draft hood outlet and the thimble.

ISPC 2017 Section 509.7.3.5(1)
Battery of fixtures (common horizontal branch)vsFixtures discharging to a common vertical stack

A battery of fixtures is two or more similar, adjacent fixtures discharging into a common horizontal waste or soil branch — not into a common vertical waste or soil stack.

ISPC 2017 Section 204.0
Work exempt from permitvsWork requiring a permit

Clearing stoppages (including removal and reinstallation of water closets) and repairing leaks in pipes, valves, or fixtures are exempt, provided the repairs do not involve or require replacement or rearrangement of valves, pipes, or fixtures.

ISPC 2017 Section 104.2(2)
Board of Appeals authorityvsAuthority Having Jurisdiction's role on the Board

The Board of Appeals shall not be empowered to waive code requirements, and the AHJ serves as an ex-officio member and secretary of the board with no vote on matters before it.

ISPC 2017 Section 107.2
Support spacing for PEX water pipingvsSupport spacing for Schedule 40 PVC/ABS DWV

PEX 1 inch and smaller requires horizontal support at intervals not exceeding 32 inches, while Schedule 40 PVC and ABS DWV with solvent-cemented joints is supported horizontally at 4-foot intervals for all sizes (with allowance for expansion every 30 feet).

ISPC 2017 Table 313.3
Existing lawful plumbing systemsvsCode appendices

Existing systems lawfully in place at adoption are permitted to continue in use, maintenance, or repair per their original design and location if no hazard is created, while appendices supplement the code and are not part of it unless formally adopted.

ISPC 2017 Section 102.2
Input rating (BTU/hr)vsUseful heat output (BTU/hr)

Input rating is the gross fuel energy supplied, while useful output is input multiplied by thermal efficiency (e.g., 75,000 × 0.80 = 60,000 BTU/hr); using input instead of output is a common sizing error.

Key Terms

Building Drain ISPC 2017 Section 204.0 - Building Drain
The lowest piping of a drainage system that receives discharge from soil, waste, and other drainage pipes inside the building walls and conveys it to the building sewer, beginning 2 feet (610 mm) outside the building wall.
Hot Water ISPC 2017 Section 210.0 - Hot Water
Water at a temperature exceeding or equal to 120°F (49°C).
Joint, Brazed ISPC 2017 Section 212.0 - Joint, Brazed
A joint made by joining metal parts with alloys that melt above 840°F (449°C) but below the melting temperature of the parts being joined.
Joint, Soldered ISPC 2017 Section 212.0 (Joint, Soldered definition)
A joint made by joining metal parts with metallic mixtures or alloys that melt at a temperature up to and including 840°F (449°C).
Horizontal Pipe ISPC 2017 Section 210.0 - Horizontal Pipe
A pipe or fitting installed in a horizontal position or making an angle of less than 45 degrees (0.79 rad) with the horizontal.
Gravity Grease Interceptor ISPC 2017 Section 209.0 - Gravity Grease Interceptor
An interceptor identified by volume, 30-minute retention time, baffle(s), not less than two compartments, a total volume of not less than 300 gallons (1135 L), and gravity separation.
Confined Space ISPC 2017 Section 205.0 (Confined Space definition)
A room or space having a volume less than 50 cubic feet per 1000 Btu/h (4.83 m³/kW) of the aggregate input rating of all fuel-burning appliances installed in that space.
Appliance, Low-Heat ISPC 2017 Section 203.0 (Appliance, Low-Heat definition)
A fuel-burning appliance producing a continuous flue gas temperature at the point of entrance to the flue of not more than 1000°F (538°C).
Chimney, Low-Heat Appliance-Type ISPC 2017 Section 205.0
A chimney suitable for removing products of combustion from low-heat appliances producing gases not in excess of 1000°F (538°C) under normal operation, but capable of handling 1400°F (760°C) during intermittent forced firing for periods up to one hour.
Bathroom Group ISPC 2017 Section 204.0 (Bathroom Group definition)
Any combination of fixtures not exceeding one water closet, two lavatories, either one bathtub or one combination bath/shower, and one shower, and may include a bidet and an emergency floor drain.
Insanitary ISPC 2017 Section 211.0 (Insanitary definition)
A condition such as a trap that does not maintain a proper trap seal, or a trap directly connected to a drainage system whose seal is not protected against siphonage and backpressure by a vent pipe.
Cross-Connection ISPC 2017 Section 205.0
A connection or arrangement, physical or otherwise, between a potable water supply system and a fixture, tank, receptor, equipment, or device through which nonpotable, used, unclean, polluted, or contaminated water or other substances may enter the potable system under any condition.
Battery of Fixtures ISPC 2017 Section 204.0
A group of two or more similar, adjacent fixtures that discharge into a common horizontal waste or soil branch.
Required inspections (Sec. 105.2) ISPC 2017 Section 105.2
The AHJ shall make three inspections — underground, rough-in (prior to installation of wall or ceiling membranes), and final (upon completion) — plus other inspections as necessary.
Inspection notification (Sec. 105.2.4) ISPC 2017 Section 105.2.4
The person doing permitted work must notify the AHJ that the work is ready for inspection not less than 24 hours before it is to be inspected.
Investigation fee (Sec. 104.5.2) ISPC 2017 Section 104.5.2
A fee collected in addition to the permit fee when work requiring a permit is started without one, equal to the amount of the permit fee required by the code, whether or not a permit is subsequently issued.
Prohibited drainage fittings (Sec. 310.1) ISPC 2017 Section 310.1
No double hub fitting, single or double tee branch, single or double tapped tee branch, side inlet quarter bend, running thread, band, or saddle may be used as a drainage fitting, except a double hub sanitary tapped tee is permitted on a vertical line as a fixture connection.
Nail plate protection (Sec. 312.9) ISPC 2017 Section 312.9
Plastic and copper or copper alloy piping penetrating framing members to within 1 inch of the exposed framing must be protected by steel nail plates not less than No. 18 gauge (0.0478 in./1.2 mm) thick.

Formulas to Know

Static/elevation pressure loss (or head)Pressure loss (psi) = vertical height (ft) × 0.433 psi/ft; only vertical elevation counts (e.g., 30 ft × 0.433 = 13.0 psi; 46 ft of vertical rise sets the head to a hose bibb, not horizontal run length).
Pressure available to overcome pipe frictionAvailable psi = static pressure at meter − elevation loss (ft × 0.433) − meter loss − other device losses (backflow preventer, PRV, etc.) − minimum required residual pressure at the fixture.
Allowable friction loss rate per 100 feetRate (psi/100 ft) = (available friction pressure ÷ total equivalent length including fittings) × 100, e.g., (22 ÷ 250) × 100 = 8.8 psi/100 ft.
Minimum static pressure required at the meter (ignoring friction)Required psi = required residual at fixture + elevation loss (ft × 0.433) + meter loss + other device losses, e.g., 45 + 22.52 + 6 + 11 = 84.52 psi.
Useful heat output of a water heaterUseful BTU/hr = input rating (BTU/hr) × thermal efficiency, e.g., 75,000 × 0.80 = 60,000 BTU/hr.
Heat energy required to heat waterBTU = gallons × 8.33 lb/gal × temperature rise (°F); rise = desired temp − incoming temp (e.g., 50 × 8.33 × 90 = 37,485 BTU).
Recovery rate in gallons per hour (and GPM for tankless)GPH = useful BTU/hr ÷ (8.33 lb/gal × temperature rise °F); for tankless flow, GPM = GPH ÷ 60 (e.g., 167,160 ÷ 583.1 = 286.7 GPH ÷ 60 = 4.78 GPM).
Time to heat a given volume (gas or electric)Time (min) = (BTU required ÷ useful BTU/hr) × 60; for electric, useful BTU/hr = watts × 3.413 (e.g., 5,500 W = 18,771.5 BTU/hr).
Hot water available during a peak hourTotal available = tank storage (gal) + recovery during the hour (gal/hr); remaining = total available − gallons drawn (e.g., 40 + 43 − 55 = 28 gal).
Combustion air free area — one permanent opening methodFree area (sq in.) = total appliance input (Btu/h) ÷ 3,000, not less than 1 sq in. per 3,000 Btu/h (e.g., 60,000 ÷ 3,000 = 20 sq in.).
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