How Hawaii licensing works
- Experience: the RME must document a minimum of 4 years of supervisory experience in plumbing work within the 10 years immediately before filing, verified with at least 3 notarized experience certificates and a detailed chronological project list.
- Application: filed with the Contractors License Board (not the BEP) with the application fee, experience certificates, project list, and a current credit report for each officer, partner, manager, or member; the Board approves the application before you're eligible to schedule the exam.
- Exam vendor: PSI. You must pass the C-37 trade exam (80 questions, 75 percent minimum passing score, 180 minutes) and, unless you already hold another Hawaii contractor license, the Business and Law exam (also 80 questions, 75 percent, 180 minutes). Both are closed book — confirm current question counts and time limits on the PSI candidate bulletin before you schedule.
- Renewal: licenses renew on a fixed biennial cycle, by September 30 of every even-numbered year; confirm current continuing-education requirements, if any, on the Board's website before your renewal date.
About the Hawaii C-37 Plumbing license
Hawaii's C-37 Plumbing Contractor license is a specialty contractor license issued by the Hawaii Contractors License Board (CLB) under Hawaii Revised Statutes chapter 444 and Hawaii Administrative Rules chapter 16-77. It authorizes a contracting business to install, repair, or alter complete plumbing systems — water supply piping, hot-water piping and water heaters, waste-water piping, fuel-gas piping, waste-water treatment systems, backflow prevention assemblies, vacuum/air/medical-gas piping, lawn sprinkler and irrigation systems, sewer lines, and solar hot-water systems, plus the trenching and surface restoration that goes with that work. Hawaii also has several narrower related sub-classifications: C-37a (sewer and drain line), C-37b (irrigation and lawn sprinkler systems), C-37c (vacuum and air systems), C-37d (water chlorination and sanitation), C-37e (treatment and pumping facilities), and C-37f (fuel dispensing).
This is a different licensing track from Hawaii's journeyman and master plumber trade licenses (PJ/PM), which are issued under HRS chapter 448E by the separate Board of Electricians and Plumbers (BEP). Passing the C-37 exam and holding the C-37 license qualifies a business to contract for plumbing work; it does not by itself authorize anyone to physically perform plumbing work. To actually perform the work, the license's Responsible Managing Employee (RME) or another employee of the contracting entity must separately hold a BEP journeyman or master plumber license — don't confuse the two boards, the two license types, or their exams while you study.
Your exam is built on the Uniform Plumbing Code (UPC), 2018 edition, published by IAPMO — that is the specific edition listed as reference material on PSI's current Hawaii contractor candidate bulletin, so confirm it hasn't changed before you test. The two model codes — the Uniform Plumbing Code (UPC) published by IAPMO and the International Plumbing Code (IPC) published by the ICC — agree on the physics but differ in tables, fixture-unit values, and some sizing methods, so always work from the one your state adopted.
Know these scope facts cold: the C-37 license is held by the contracting entity, qualified by its RME's experience and exam; most work requires a permit and inspection (rough-in/top-out and final); you must work within the classification you hold; and unlicensed or out-of-scope plumbing work is a violation that can cost you the license and carry penalties. Plumbing protects public health — the exam constantly returns to the two core purposes of the code: deliver safe potable water and remove waste without contaminating that water.
How Hawaii licensing works
- Experience: the RME must document a minimum of 4 years of supervisory experience in plumbing work within the 10 years immediately before filing, verified with at least 3 notarized experience certificates and a detailed chronological project list.
- Application: filed with the Contractors License Board (not the BEP) with the application fee, experience certificates, project list, and a current credit report for each officer, partner, manager, or member; the Board approves the application before you're eligible to schedule the exam.
- Exam vendor: PSI. You must pass the C-37 trade exam (80 questions, 75 percent minimum passing score, 180 minutes) and, unless you already hold another Hawaii contractor license, the Business and Law exam (also 80 questions, 75 percent, 180 minutes). Both are closed book — confirm current question counts and time limits on the PSI candidate bulletin before you schedule.
- Renewal: licenses renew on a fixed biennial cycle, by September 30 of every even-numbered year; confirm current continuing-education requirements, if any, on the Board's website before your renewal date.
How Hawaii licensing works
- Experience: the RME must document a minimum of 4 years of supervisory experience in plumbing work within the 10 years immediately before filing, verified with at least 3 notarized experience certificates and a detailed chronological project list.
- Application: filed with the Contractors License Board (not the BEP) with the application fee, experience certificates, project list, and a current credit report for each officer, partner, manager, or member; the Board approves the application before you're eligible to schedule the exam.
- Exam vendor: PSI. You must pass the C-37 trade exam (80 questions, 75 percent minimum passing score, 180 minutes) and, unless you already hold another Hawaii contractor license, the Business and Law exam (also 80 questions, 75 percent, 180 minutes). Both are closed book — confirm current question counts and time limits on the PSI candidate bulletin before you schedule.
- Renewal: licenses renew on a fixed biennial cycle, by September 30 of every even-numbered year; confirm current continuing-education requirements, if any, on the Board's website before your renewal date.
About the Hawaii C-37 Plumbing license
Hawaii's C-37 Plumbing Contractor license is a specialty contractor license issued by the Hawaii Contractors License Board (CLB) under Hawaii Revised Statutes chapter 444 and Hawaii Administrative Rules chapter 16-77. It authorizes a contracting business to install, repair, or alter complete plumbing systems — water supply piping, hot-water piping and water heaters, waste-water piping, fuel-gas piping, waste-water treatment systems, backflow prevention assemblies, vacuum/air/medical-gas piping, lawn sprinkler and irrigation systems, sewer lines, and solar hot-water systems, plus the trenching and surface restoration that goes with that work. Hawaii also has several narrower related sub-classifications: C-37a (sewer and drain line), C-37b (irrigation and lawn sprinkler systems), C-37c (vacuum and air systems), C-37d (water chlorination and sanitation), C-37e (treatment and pumping facilities), and C-37f (fuel dispensing).
This is a different licensing track from Hawaii's journeyman and master plumber trade licenses (PJ/PM), which are issued under HRS chapter 448E by the separate Board of Electricians and Plumbers (BEP). Passing the C-37 exam and holding the C-37 license qualifies a business to contract for plumbing work; it does not by itself authorize anyone to physically perform plumbing work. To actually perform the work, the license's Responsible Managing Employee (RME) or another employee of the contracting entity must separately hold a BEP journeyman or master plumber license — don't confuse the two boards, the two license types, or their exams while you study.
Your exam is built on the Uniform Plumbing Code (UPC), 2018 edition, published by IAPMO — that is the specific edition listed as reference material on PSI's current Hawaii contractor candidate bulletin, so confirm it hasn't changed before you test. The two model codes — the Uniform Plumbing Code (UPC) published by IAPMO and the International Plumbing Code (IPC) published by the ICC — agree on the physics but differ in tables, fixture-unit values, and some sizing methods, so always work from the one your state adopted.
Know these scope facts cold: the C-37 license is held by the contracting entity, qualified by its RME's experience and exam; most work requires a permit and inspection (rough-in/top-out and final); you must work within the classification you hold; and unlicensed or out-of-scope plumbing work is a violation that can cost you the license and carry penalties. Plumbing protects public health — the exam constantly returns to the two core purposes of the code: deliver safe potable water and remove waste without contaminating that water.
This is the opening of the full study guide. The complete guide continues into code navigation, worked calculations and solved exam questions.
