The Massachusetts Master Plumber Guide

What Is the Massachusetts Master Plumber License?

In Massachusetts, plumbers are regulated by the Board of State Examiners of Plumbers & Gas Fitters, and the Master Plumber examination is administered for the board by PSI at computer-based testing centers. As the PSI Candidate Information Bulletins (597 and 598, dated October 3, 2025) put it: “Examinations are CLOSED BOOK, computer generated and two parts.” Both parts — the written and the practical — are required for licensure, and both are closed book.

That two-part, closed-book design makes Massachusetts fundamentally different from the open-book, bring-your-code states. There is no code on the desk to lean on: Part I tests whether you know the substance of the Massachusetts plumbing code and gas regulations, and Part II tests whether you can do the work of a master — read an isometric system, run the trade calculations, and lay out gas piping and venting — by hand with nothing but scrap paper and a basic calculator.

The practical consequence of the structure is scheduling discipline. Because both parts are required and passing scores are valid for one year only, you are always working against a clock: pass one part and you have one year to complete the other. Candidates who fail a part retake only the part they failed — there is no limit on retake attempts for the Master Plumber exam — but a passing score does not wait for you.

Exam Format: Two Required Parts, Closed Book

The Massachusetts Master Plumber examination is delivered by PSI as two separate, computer-generated parts. At a glance:

Three details deserve a second read. First, both parts are required — passing Part I alone licenses nothing. Second, closed book means the code list that defines the exam's scope is the basis questions are drawn from, not material you may consult during the test; the only item on your desk beyond the computer is scrap paper. Third, the one-year validity rule for passing scores and the retake-only-the-failed-part policy work together: the path to licensure is passing each part once, within a year of the other.

Part I — The Written Exam: 80 Questions, 160 Minutes, 70% to Pass

Part I (Written) is 80 questions in 160 minutes — about two minutes per question — with a 70% passing score (56 correct of 80). The bulletin breaks the 80 questions across 12 subject areas:

The blueprint tells a clear story: this is a gas-heavy, drainage-heavy written exam. Gas Piping / Equipment / Appliances (21), Drain/Waste/Vent (13) and Venting (12) together account for 46 of the 80 questions — more than half of Part I — before you add General Regulations, Inspections and Permits (9). If you study the Massachusetts gas rules under 248 CMR, the D/W/V systems of the Uniform State Plumbing Code, and venting theory first, you have already covered the majority of the written exam's weight.

Part II — The Practical Exam: 40 Items, 160 Minutes, 70% to Pass

Part II (Practical) is 40 items in 160 minutes — about four minutes per item — with a 70% passing score (28 of 40 items). Where Part I tests knowledge across the code, Part II tests applied trade skill. The bulletin breaks the 40 items across four areas:

The headline number is Isometric Analysis at 20 of 40 items — exactly half of the practical exam. If you cannot read a set of isometrics and lay out the system they describe, fluently and by hand, Part II is effectively over before it begins. The remaining half splits between the trade calculations (5) and the gas side of the trade — Gas Piping (7) and Gas Venting (8) put 15 of 40 items on gas, mirroring the written exam's own gas-heavy weighting.

What You Can Bring: A Calculator — and Almost Nothing Else

Because both parts are closed book, the permitted-materials list is short: only a non-programmable, silent calculator is allowed. Scrap paper is provided at the testing center. Codebooks, notes, tabbed references, formulas sheets and programmable devices have no place on the desk.

Two habits follow from this. First, practice the way you will test: the Part II calculation and layout items should be drilled by hand, on paper, with a plain calculator — not in a polished software tool that quietly does the isometric arithmetic for you. Second, carry the code in your head, because no part of the Massachusetts code walks into the room with you. The 248 CMR content the written exam draws on — gas rules, D/W/V, venting, water supply — has to be knowledge you own, not a section you can flip to.

The Code Basis: 248 CMR, the MA Uniform State Plumbing Code & MGL 142

The PSI bulletins list the references the examination questions are based on — material you must study before the exam, not consult during it. The code basis for the Massachusetts Master Plumber examination includes:

• 248 CMR 3.00, 4.00, 5.00 and 11.00 (2021)
• 248 CMR 6.00 (2014 NFPA 58)
• 248 CMR 7.00 (2014 — large gas equipment)
• Massachusetts Uniform State Plumbing Code 2023 (248 CMR 10.00–10.23)
• MGL provisions and MGL 142
• NFPA 54 (2012) and NFPA 58 (2011)

The through-line across the blueprint and the reference list is gas: 248 CMR 6.00 and 7.00 carry the gas rules, NFPA 54 is the National Fuel Gas Code and NFPA 58 is the LP-Gas Code, and gas questions are the single heaviest column of Part I (21) while gas piping and venting add another 15 items in Part II. The written blueprint's venting and combustion-air items, the water-heater items under MGL 142, and the gas layout work in the practical all reach into this same body of regulation.

Fees, Retakes & Passing Scores

• Exam administration fee: $80, for a first attempt or a retake of either part.
• License fee: $78 Master Plumber license fee, paid through eLIPSE.
• Two parts, both required: pass Part I (Written) and Part II (Practical); neither part alone earns the license.
• Passing-score validity: passing scores are valid for one year only — complete the second part within that window.
• Retakes: fail one part and you retake only that part; there is no limit on retake attempts for the Master Plumber examination.
• Veteran credit: veterans receive a 5% credit added to each part of the examination, with their DD214.

The structure rewards finishing what you start. Because a passing score is valid for one year only, a candidate who passes Part I and lets the year lapse has lost the credit — while a candidate who fails Part II keeps the passed Part I score and retakes only the practical. There is no penalty spiral of repeating both parts, but there is a hard calendar: the two parts have to be completed within one year of each other.

How to Prepare for the Massachusetts Master Plumber Exam

1. Study the Massachusetts code, not a generic IPC. The exam is closed book and built on the Massachusetts code basis: 248 CMR, the Massachusetts Uniform State Plumbing Code 2023 (248 CMR 10.00–10.23), MGL 142 and the listed NFPA references. Your prep has to teach the actual Massachusetts regulations — the board's rules and the state's code, including the gas rules of 248 CMR 6.00 and 7.00.
2. Work both blueprints, weighted. For Part I, drill the heavy columns first — Gas Piping/Equipment/Appliances (21), Drain/Waste/Vent (13) and Venting (12) are 46 of the 80 questions. For Part II, treat Isometric Analysis (20 of 40 items) as the subject you cannot afford to be slow at.
3. Learn the material in your head, not in the margins. Closed book means no code on the desk. Read to retain: 248 CMR section by section, the plumbing code's system rules, venting and combustion requirements, and the gas tables — until you can answer without flipping.
4. Drill Part II by hand. Isometrics, trade calculations, gas piping and gas venting are pencil-and-paper skills. Practice laying out and reading isometrics on scrap paper with a non-programmable silent calculator, the exact conditions of the testing room, until the layout work is automatic.
5. Simulate each part separately, under time. Part I is 80 questions in 160 minutes; Part II is 40 items in 160 minutes. Run full-length, timed simulations of each format at the 70% line (56 of 80 on the written, 28 of 40 on the practical) so pacing — not the material — is never what costs you.
6. Use a curriculum built for both parts. MasterPlumberPractice organizes its Massachusetts program (MA-MST) around this exact two-part structure, with a curriculum spanning 16 chapters across both parts and the 248 CMR focus the closed-book exam demands — written-exam theory on one side and practical trade skills on the other.

MasterPlumberPractice is built for exactly this exam: Massachusetts-specific content aligned to the Part I written blueprint and the Part II practical skills, the full 248 CMR theory behind the written exam, and timed simulations of both the 80-question and the 40-item formats — practice the actual two-part structure so the real exam feels like a repeat. Start with free practice questions to feel the format, and create a free account to track your progress on both parts as you go.

Frequently Asked Questions

Ready to Earn the Massachusetts Master License?

The Massachusetts Master Plumber exam is two parts and closed book — the written exam tests what you know of 248 CMR, and the practical tests what you can do by hand on paper. Prepare for both halves with the full 248 CMR theory guides, try free Massachusetts practice questions, register free and see the all-inclusive pricing — one subscription covering both parts of the Massachusetts blueprint, so you never buy written-exam and practical prep piece by piece.