Maryland licenses stationary engineers in five grades through its State Board of Stationary Engineers, with examinations administered by PSI. Grade 1 engineers oversee plant machinery of five hundred or more horsepower; Grades 2, 3, 4, and 5 step down through three hundred, one hundred, and thirty horsepower floors, Grade 5 limited to buildings not open for public use. The PSI examinations run sixty questions, open book, at Grades 5 and 4, and eighty questions, closed book, at Grades 3, 2, and 1 — every grade at seventy percent in one hundred twenty minutes.
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What this licence authorizes
Maryland’s stationary engineer system is the most formally examined in this family: five grades of licence, a state board, a national testing vendor, published content outlines, and a passing standard printed in the vendor’s bulletin. The State Board of Stationary Engineers, in the Maryland Department of Labor, licenses engineers to take charge of plant machinery by horsepower bands. Grade 1 takes charge of plant machinery of five hundred or more horsepower; Grade 2, three hundred to four hundred ninety-nine; Grade 3, one hundred to two hundred ninety-nine; Grade 4, thirty to ninety-nine horsepower in any building; Grade 5, the same thirty to ninety-nine band but only in a building not open for public use.
Two Maryland rules shape everything else. The grade is set by the horsepower and operating pressure of the largest single piece of equipment in the plant — not the combined total — a point the Board’s own FAQ repeats because candidates and employers keep getting it wrong. And every grade requires the state examination: the Board’s position, carried in the scope for this family and confirmed in the PSI bulletin, is that applicants for each grade must first pass the examination for that grade, administered by PSI at test centres across Maryland. The examinations divide at Grade 3: Grades 5 and 4 are sixty-question, open-book sittings; Grades 3, 2, and 1 are eighty-question, closed-book sittings; all five allow one hundred twenty minutes and require seventy percent.
The examination at a glance
| Item | Verified position |
|---|---|
| Licence | Maryland Stationary Engineer — Grades 1, 2, 3, 4, and 5 |
| Regulator | State Board of Stationary Engineers, Maryland Department of Labor (Division of Occupational and Professional Licensing) |
| Legal basis | Maryland Stationary Engineers Act, Business Occupations and Professions Article, Title 6.5, Annotated Code of Maryland; COMAR Title 09, Subtitle 17 |
| Grade 1 authority | Take charge of plant machinery of 500 or more horsepower (any building) |
| Grade 2 authority | 300 to 499 horsepower (any building) |
| Grade 3 authority | 100 to 299 horsepower (any building) |
| Grade 4 authority | 30 to 99 horsepower (any building regardless of use) |
| Grade 5 authority | 30 to 99 horsepower (in a building not open for public use) |
| Grade assignment rule | By the horsepower and operating pressure of the largest single piece of equipment in the plant, not the combined total (Board FAQ; Act section 6.5-302) |
| Examination vendor | PSI Services LLC — prior PSI approval required; examinations Monday through Friday by appointment at Maryland test centres |
| Grades 5 and 4 examination | 60 questions, 70% passing (42 items correct), 120 minutes, OPEN BOOK — listed references may be brought, under the bulletin’s marking and tabbing rules |
| Grades 3, 2, and 1 examination | 80 questions, 70% passing (56 items correct), 120 minutes, CLOSED BOOK |
| Examination fee | PSI examination registration fee $65 per sitting (a vendor fee per the PSI bulletin; valid for one examination, 90 days) |
| Direct entry | It is not necessary to start at a lower grade: an applicant may apply for any grade whose minimum requirements they meet (PSI bulletin) |
The five grades
Each grade states its authority, the qualification routes the PSI bulletin publishes for its examination, and its examination form. The outlines are PSI’s published subject areas with their item counts.
Grade 5 — 30 to 99 horsepower, buildings not open for public use
The entry grade, and the only one whose qualification is educational rather than experiential: an applicant qualifies for the Grade 5 examination by possessing a high school diploma or graduate equivalence diploma. The licence it leads to is the system’s narrowest — charge of plant machinery from thirty to ninety-nine horsepower, in a building not open for public use: the private industrial and institutional plant whose boilers serve the building’s own operations rather than the visiting public. The examination is the sixty-question open-book sitting: general knowledge and problem solving carrying twenty of the sixty items, with basic electricity, boiler types and equipment, burners and fuel train, pumps and valves, inspections and maintenance, water treatment, emergency operations, and auxiliary equipment at five each.
Grade 4 — 30 to 99 horsepower, any building
Grade 4 removes Grade 5’s building restriction: the same horsepower band, in any building regardless of use — the grade for the operator of the school, the hospital annex, the public building. Qualification is by one of two routes: six months of documented experience as an active Grade 5 stationary engineer, or three credit hours or continuing education units of classes in boiler operations or safety together with verification of work experience. The examination is the same sixty-question, one-hundred-twenty-minute, open-book form as Grade 5, with the same published outline and passing standard of seventy percent — forty-two items correct.
Grade 3 — 100 to 299 horsepower
Grade 3 is the system’s hinge: the horsepower band rises to one hundred through two hundred ninety-nine, and the examination changes character — eighty questions, closed book, in the same one hundred twenty minutes, seventy percent requiring fifty-six correct. Qualification routes: two years of documented experience as an active Grade 4 or Grade 5 engineer; or one such year plus six credit hours or continuing education units in boiler operations or safety; or a valid marine engineer’s certificate or a United States Navy Chief Petty Officer’s certificate; or equivalent experience submitted to the Board. The outline deepens: sequential operations and central station and chillers enter, boiler types, burners, pumps, and sequential operations rise to ten items each, and general knowledge falls to ten.
Grade 2 — 300 to 499 horsepower
Grade 2 takes charge of plant machinery from three hundred to four hundred ninety-nine horsepower — the large institutional and industrial plant. Its principal qualification route is thirty-six months of documented experience as an active Grade 3 engineer under the direction and control of a licensed Grade 2 or Grade 1 engineer, with credit available: one year for six credit hours of boiler safety or operations classes, and one year for holding a current active licence as a master plumber, master HVACR contractor, or master restricted HVAC contractor. Alternative routes include a four-year mechanical engineering degree, licensing as a professional engineer with six months of documented experience at Grades 3 to 5, or a marine or Navy Chief Petty Officer certificate. The examination is eighty questions, closed book, seventy percent, with the outline’s weight shifted toward inspections and maintenance and water treatment at ten items each.
Grade 1 — 500 or more horsepower
The unlimited-floor grade: charge of plant machinery of five hundred or more horsepower in any building — the central plants of hospitals, universities, and industry. The principal route is five years of documented experience as an active Grade 2 engineer under the direction and control of a Grade 1 engineer, toward which the same class-credit and master-licence credits may be received. A four-year mechanical engineering degree is an alternative route, as is licensing as a professional engineer with one year of documented experience as a professional engineer and one year as a Grade 2 engineer under a Grade 1’s direction and control. The examination shares the eighty-question closed-book form and the Grade 2 outline family: burners, pumps, sequential operations, inspections, and water treatment at the heavy end.
Who this licence serves
Maryland’s grades serve the plant workforce of the Baltimore–Washington corridor and the state’s institutions: hospital and university central plants, government buildings, manufacturing steam plants, and the large commercial buildings whose single largest boiler or chiller sets the grade of the engineer who must be in charge of it. The single-piece rule makes the workforce legible — walk into a plant, read the largest nameplate, and you know the grade the law requires at its head.
The direct-entry rule shapes careers differently from a ladder state: because an applicant may apply for any grade whose requirements they meet, experience earned in any setting — marine, Navy, another state’s plant, a master trade licence — can be presented at the grade it supports, rather than re-climbed rung by rung.
The route, in order
Step one is examination, and it comes before licensing: the applicant applies to PSI online, uploads the eligibility documentation for the grade, and waits for PSI’s review — up to a week for processing — after which the approval email carries the instructions to pay the sixty-five dollar registration fee and schedule. Examinations run Monday through Friday by appointment at PSI test centres in Maryland, including Baltimore, College Park, Hagerstown, Lanham, and Salisbury per the Board’s pages. The registration fee is valid for one examination and for ninety days, and is neither refundable nor transferable.
Step two begins on passing: the application for original licensing is sent by the Department, and the licence issues under the Board for the grade passed. Candidates should note the order carefully — Maryland examines first and licenses second, so the PSI bulletin, not the licence application, is the document that governs the first half of the route.
What makes this examination demanding
The open-book sittings are demanding in a way candidates underestimate: sixty questions in one hundred twenty minutes against a shelf of references is a retrieval race, and the bulletin’s marking rules — no writing in the books, no loose papers, only approved tabs — mean the race is run with books prepared in advance or not at all. General knowledge and problem solving, at twenty of sixty items, is deliberately the largest single area: the part of the examination least findable in a reference book carries the most weight.
The closed-book grades invert the problem. Eighty questions across eleven subject areas, from memory, at a pace of ninety seconds an item, with sequential operations and the grade-level systems — central station and chillers — examined in depth. Maryland publishes its outlines with item counts, which is an invitation to prepare arithmetically: the candidate who allocates study time by the published counts is using the bulletin as it was designed to be used.
The credential at work
A Maryland grade is a precise labour-market signal because its meaning is a number: the horsepower of the largest single piece of machinery its holder may take charge of. Employers staff to nameplates, and the grades align the workforce to them from the ninety-nine-horsepower private plant to the five-hundred-plus central plant. The PSI-examined, Board-licensed structure also makes the credential portable across the state’s employers in a way plant-specific licences are not: the grade means the same thing in Hagerstown as in Baltimore.
What the PassProfessor program will cover
Practice in the examination’s own shape. Maryland’s PSI examinations are multiple-choice sittings of sixty questions (Grades 5 and 4, open book) or eighty questions (Grades 3, 2, and 1, closed book), each in one hundred twenty minutes at a seventy percent standard. The program in the works practises in those shapes: timed sets at the grade’s own count and pace, open-book technique drills for Grades 5 and 4 under the bulletin’s marking rules, and closed-book recall sets for Grades 3 to 1, with study weighted to PSI’s published outlines item by item.
Written from the primary sources. The program is written from the PSI Qualification Information Bulletin for the Maryland State Board of Stationary Engineers and the Board’s own pages — the outline counts, examination forms, fees, and qualification routes the bulletin prints, and the grade authorities the Act and the Board’s FAQ state. Where Maryland’s single-piece horsepower rule differs from other states’ plant-total rules, the program teaches the Maryland rule and names the difference.
The whole candidate, not only the test-taker. Around the item practice, the program carries the State Board of Stationary Engineers route as the authority publishes it — PSI approval and examination first, then the Board’s licence — with the grade set by the largest single piece of equipment in the plant — because a written examination is a means to a licence, and candidates plan better when the destination is mapped.
Preparation only. This is preparation for examinations administered by PSI for the Maryland State Board of Stationary Engineers. PassProfessor is not affiliated with PSI or the Board, no completion of this program is reported to either, and nothing in the program substitutes for the documented experience any grade requires or for any step in the licensing process.
Tell me when enrollment opens. The Maryland Stationary Engineer program is in the works and enrollment is not yet open. Leave an email address and PassProfessor will write to you when the program is ready — and only about this program. No date is promised, because the program will open when it meets the standard described above, not before.
Frequently asked questions
Who administers the Maryland stationary engineer examinations?
PSI Services LLC, under contract with the State Board of Stationary Engineers. Prior PSI approval is required: you apply to PSI online with your eligibility documents, and on approval you pay and schedule.
What are the five grades’ horsepower bands?
Grade 1: 500 or more horsepower. Grade 2: 300 to 499. Grade 3: 100 to 299. Grade 4: 30 to 99 in any building. Grade 5: 30 to 99 in a building not open for public use.
Is the grade based on the plant’s total horsepower?
No. The Board’s rule is the horsepower and operating pressure of the largest single piece of equipment in the plant, not the combined total.
Which examinations are open book?
Grades 5 and 4: sixty questions, open book, under the bulletin’s reference and tabbing rules. Grades 3, 2, and 1 are closed book, at eighty questions. All five allow one hundred twenty minutes and require seventy percent.
Must I start at Grade 5 and climb?
No. The PSI bulletin states that it is not necessary to start on a lower grade — you may apply for any grade whose minimum requirements you meet, or whose equivalent experience the Board approves.
What does the examination cost?
PSI’s examination registration fee is sixty-five dollars per sitting — a vendor fee stated in the PSI bulletin — valid for one examination and for ninety days, non-refundable and non-transferable.
What qualifies me for Grade 5?
A high school diploma or graduate equivalence diploma. Grade 5 is the one grade whose bulletin qualification is educational rather than experiential.
What is the Grade 1 experience route?
Five years of documented experience as an active Grade 2 engineer under the direction and control of a Grade 1 engineer, with credits the bulletin specifies — or the bulletin’s degree, professional-engineer, or equivalent-experience routes.
What happens after I pass?
The Department sends the application for original licensing, and the Board issues the licence for the grade passed. Maryland examines first and licenses second.
Is PassProfessor affiliated with PSI or the Maryland Board?
No. PassProfessor is an independent preparation provider. The program confers no licence and reports nothing to PSI or the Board.