Exam Cheat Sheet · Quick Reference

Idaho - PLUMBING 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

100

Passing score

Exam time

180 min

Administered by

PSI Services Contractor

Format

Reference materials allowed

Idaho State Portion 100 questions

2017 Idaho State Plumbing Code Chapter 1 5 Q · 5%

2017 Idaho State Plumbing Code Chapter 2 5 Q · 5%

2017 Idaho State Plumbing Code Chapter 3 5 Q · 5%

2017 Idaho State Plumbing Code Chapter 4 5 Q · 5%

2017 Idaho State Plumbing Code Chapter 5 10 Q · 11%

2017 Idaho State Plumbing Code Chapter 6 11 Q · 12%

2017 Idaho State Plumbing Code Chapter 7 11 Q · 12%

2017 Idaho State Plumbing Code Chapter 8 6 Q · 6%

2017 Idaho State Plumbing Code Chapter 9 10 Q · 11%

2017 Idaho State Plumbing Code Chapter 10 7 Q · 7%

2017 Idaho State Plumbing Code Chapter 11 4 Q · 4%

2017 Idaho State Plumbing Code Chapter 12 8 Q · 9%

2017 Idaho State Plumbing Code Chapter 14 1 Q · 1%

2017 Idaho State Plumbing Code Chapter 15 2 Q · 2%

2017 Idaho State Plumbing Code Chapter 16 1 Q · 1%

2017 Idaho State Plumbing Code Chapter 17 1 Q · 1%

Plumbing sizing using schematics provided during exam (2 questions; 4pts each) 2 Q · 2%

Key Distinctions

AccessiblevsReadily Accessible

'Accessible' may require removal of an access panel or similar obstruction to reach, while 'Readily Accessible' allows direct access without removing any panel, door, or obstruction.

2017 ISPC, Section 203.0

Clearing Stoppages / Repairing Leaks (no replacement)vsReplacing Defective Pipe with New Material

Clearing stoppages and repairing leaks without replacing or rearranging valves, pipes, or fixtures is permit-exempt; removing and replacing defective pipe with new material is classified as new work and requires a permit and inspection.

2017 ISPC Section 104.2

Permit Application Expiration (no permit issued)vsIssued Permit Expiration (work not commenced)

A permit application expires after 180 days if no permit is issued; an already-issued permit expires and becomes null and void if authorized work is not commenced within 180 days of the permit date.

2017 ISPC Section 104.3.3

Plumbing CodevsMechanical Code

When the plumbing code and mechanical code conflict, the plumbing code prevails.

2017 ISPC Section 102.1

General RequirementvsSpecific Requirement

Where a general requirement and a specific requirement conflict in the 2017 ISPC, the specific requirement prevails.

2017 ISPC, Section 102.1

Hose Bibb on Reclaimed Water (public area)vsQuick-Disconnect Device on Reclaimed Water (public area)

Hose bibbs are prohibited on reclaimed water piping in areas accessible to the public; access must instead be provided through a quick-disconnect device that differs from those on the potable water system.

2017 ISPC Section 1503.9

Potable Water Makeup Supply (non-pressurized tank)vsReclaimed Water Makeup Supply (non-pressurized tank)

Potable water used as makeup water for a non-pressurized storage tank must be protected by an air gap; reclaimed water systems may also allow a reduced-pressure principle backflow preventer in addition to an air gap.

2017 ISPC Section 1504.4

Underground InspectionvsRough-In Inspection

Underground inspection occurs before underground plumbing is covered, while rough-in inspection must be made prior to the installation of wall or ceiling membranes; both are among the three required AHJ inspections (underground, rough-in, final).

2017 ISPC, Section 105.2

Work Commenced Without Permit (investigation fee)vsNormal Permit Fee

When work is started before a permit is obtained, a special investigation is required and an investigation fee equal to the permit fee is collected in addition to the normal permit fee.

2017 ISPC, Sections 104.5.1 and 104.5.2

Moved/Relocated Building PlumbingvsOriginal In-Place Building Plumbing

Plumbing in a building moved from one location to another must comply with provisions for new installations and be completely tested as prescribed for new work, unlike existing in-place plumbing that may remain if code-compliant.

2017 ISPC, Section 102.7

Flush-Valve Water Closet DFU RatingvsLavatory / Floor Drain / Service Sink DFU Rating

Per UPC Table 702.1, flush-valve water closets are rated at 6 DFU each, while lavatories are 1 DFU, floor drains are 2 DFU, and service sinks are 3 DFU each.

UPC Chapter 7, Table 702.1 (Drainage Fixture Unit Values)

Stop Work OrdervsNormal Work Authorization

When the AHJ issues a stop work order for work contrary to code provisions, all work must cease immediately and may not resume until the AHJ authorizes continuation; normal work authorization allows work to proceed once a permit is issued.

2017 ISPC, Section 106.4

Key Terms

Primary Purpose of the 2017 ISPC (Section 101.3) 2017 ISPC Section 101.3

The 2017 Idaho State Plumbing Code is an ordinance providing minimum requirements and standards for the protection of the public health, safety, and welfare.

Plumbing Code Prevails Over Mechanical Code (Section 102.1) 2017 ISPC, Section 102.1

Per 2017 ISPC Section 102.1, where plumbing code requirements conflict with mechanical code requirements, the plumbing code shall prevail; where a general and specific requirement conflict, the specific requirement prevails.

Permit Application Expiration (Section 104.3.3) 2017 ISPC Section 104.3.3

Per 2017 ISPC Section 104.3.3, a permit application for which no permit is issued shall expire by limitation after 180 days following the date of application.

Permit Expiration – Work Not Commenced (Section 104.4.3) 2017 ISPC, Section 104.4.3

Per 2017 ISPC Section 104.4.3, an issued permit expires and becomes null and void if authorized work is not commenced within 180 days; a new permit at one-half the fee may be obtained if no changes were made and suspension has not exceeded one year.

Permit Exemptions (Section 104.2) 2017 ISPC Section 104.2

Per 2017 ISPC Section 104.2, no permit is required for clearing stoppages (including water closet removal/reinstallation) or repairing leaks, provided no replacement or rearrangement of valves, pipes, or fixtures is involved.

Defective Pipe Replacement = New Work (Section 104.2(1)) 2017 ISPC Section 104.2

Per 2017 ISPC Section 104.2(1), when a trap, drain pipe, soil, waste, or vent pipe becomes defective and must be removed and replaced with new material, it is considered new work requiring a permit and inspection.

Cover / Concealment Prohibition Before Inspection (Sections 105.1 & 105.2) 2017 ISPC, Sections 105.1 and 105.2.1.2

Per 2017 ISPC Sections 105.1 and 105.2, no plumbing system or portion thereof shall be covered, concealed, or put into use until it has been tested, inspected, and approved; a rough-in inspection must be made before wall or ceiling membranes are installed.

Board of Appeals Limitations (Section 107.2) 2017 ISPC Section 107.2

Per 2017 ISPC Section 107.2, the Board of Appeals has no authority to interpret administrative provisions of the code and is not empowered to waive any code requirements.

Each Day a Violation Continues = Separate Offense (Section 106.3) 2017 ISPC Section 106.3

Per 2017 ISPC Section 106.3, each separate day or portion thereof during which a violation of the code occurs or continues shall be deemed to constitute a separate offense.

Stop Work Order (Section 106.4) 2017 ISPC, Section 106.4

Per 2017 ISPC Section 106.4, where work is being done contrary to code provisions the AHJ may order work stopped, and persons so ordered must immediately cease work until authorized to proceed.

Inspection Notice Requirement (Section 105.2.4) 2017 ISPC, Section 105.2.4

Per 2017 ISPC Section 105.2.4, the permit holder must notify the AHJ that work is ready for inspection not less than 24 hours before the work is to be inspected.

Reinspection Fee (Section 105.2.6) 2017 ISPC, Section 105.2.6

Per 2017 ISPC Section 105.2.6, a reinspection fee may be assessed when work is not complete, corrections have not been made, approved plans are not available, access is not provided, or plans were deviated from without approval.

Drainage Fixture Unit (DFU) UPC Chapter 7, Table 702.1 (Drainage Fixture Unit Values)

A DFU is a unit of measure used to estimate the load-producing effect of different plumbing fixtures on the sanitary drainage system; per UPC Table 702.1, flush-valve water closets = 6 DFU, lavatories = 1 DFU, floor drains = 2 DFU, service sinks = 3 DFU.

Reclaimed (Recycled) Water – Hose Bibb Prohibition (Section 1503.9) 2017 ISPC Section 1503.9

Per 2017 ISPC Section 1503.9, hose bibbs shall not be installed on reclaimed water piping in areas accessible to the public; public access must be through a quick-disconnect device that differs from potable system devices.

Air Gap – Potable Makeup Water for Non-Pressurized Tank (Section 1504.4) 2017 ISPC Section 1504.4

Per 2017 ISPC Section 1504.4, potable or reclaimed water may be used as makeup water for a non-pressurized storage tank only if the supply is protected by an air gap in accordance with the code.

Riser Diagram Required Contents (UPC Section 301.5.3) UPC Section 301.5.3

Per UPC Section 301.5.3, design documents must include floor plans and a riser diagram indicating, where appropriate, the direction of flow, pipe sizes, grade of horizontal piping, loading, and location of fixtures and appliances.

Formulas to Know

Total Drainage Fixture Units (DFU) on a Stack

Total DFU = Σ (fixture count × DFU rating per fixture type) for all floors; e.g., flush-valve WC × 6 + lavatory × 1 + floor drain × 2 + service sink × 3

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