QMED Exam Domains 2026: Complete Guide to All 2 Content Areas

Two Modules, Not Weighted Domains

Most certification exams publish a blueprint that says, for example, "Domain 3 is 22 percent of scored questions." The National QMED endorsement for Electrician/Refrigerating Engineer does not work that way. The U.S. Coast Guard National Maritime Center (NMC) publishes two examination modules for the QMED02 endorsement: Q802 Electrician and Q803 Refrigerating Engineer. Each module has its own published topic list, and that list is the authoritative description of what a candidate is expected to know.

That distinction matters for how you study. There is no official percentage split to optimize against, so you cannot "skip the small domain." Treat each module as a complete body of knowledge. If you are new to the credential itself, the overview in What Is QMED? and the explainer on what QMED stands for provide the background, while this article stays focused on content areas.

What the Endorsement Covers

The scope here is the QMED02 Electrician-Refrigerating Engineer endorsement specifically. It is a different rating from the Junior Engineer, Oiler, Boiler Technician-Watertender, or Machinist-Pump Technician QMED ratings, each of which has its own NMC module list. If you pull a study resource written for one of those other ratings, much of the content will not map onto Q802 or Q803, and some of what you need will be missing.

The endorsement pairs two disciplines that live side by side in a ship's engineering spaces: the electrical plant and the refrigeration and air-conditioning plant. The two modules mirror that pairing. For eligibility, sea-service and application questions, see QMED Requirements 2026: Eligibility, Prerequisites & How to Qualify, and for a broader orientation to how the exam is structured, the QMED Study Guide is the companion piece to this one.

Domain 1: Electrician (Q802)

The Q802 Electrician module is the more electrically intensive of the two, and its published list is long. It combines general engine-room knowledge, a deep electrical block, safety and environmental protection, and a set of shipboard systems.

Notice the steering entry. Steering gear sits in the Q802 shipboard-systems list but not in Q803, reflecting the electrical and control side of that equipment. Candidates preparing for the electrician module should be able to connect the electrical block to real shipboard loads: how a motor controller feeds a pump, how distribution reaches the machinery that the general-subjects list names, and how to troubleshoot when it fails.

Domain 2: Refrigerating Engineer (Q803)

The Q803 module keeps the same general-subjects spine as Q802 but swaps the deep electrical block for thermal, fluid and refrigeration content. Electrical topics still appear, but in a narrower form.

Note what Q803 does not list: A/C circuits, D/C circuits, batteries, generation equipment, distribution systems, and communication devices. Those belong to Q802. A candidate who takes the refrigerating engineer module should still understand how motors and controllers behave, but the emphasis shifts to the refrigeration cycle, heat transfer, and the piping and valves that move working fluids through the plant.

Topics Both Modules Share

A large portion of both lists is identical, and that overlap is one of the best study efficiencies in this endorsement. The shared material falls into three clusters.

Engineering fundamentals

Auxiliary machinery, bearings, care of equipment and machine parts, drawings and tables, instrumentation principles, maintenance procedures, measuring instruments, pollution prevention, pumps, fans, and blowers, remote control equipment, and use of hand/power tools appear in both modules. Reading a drawing or table, selecting the right measuring instrument, and following sound maintenance procedure are skills that transfer directly between Q802 and Q803.

Safety and environmental protection

Both modules carry the same safety block: communications, damage control, elementary first aid, emergency equipment, environmental awareness, fire prevention, firefighting equipment, firefighting principles, general safety, and hazardous materials. These are practical, scenario-friendly topics. Expect to apply them rather than merely recite them, for example by deciding what equipment or procedure fits a given emergency.

Electrical overlap

Electronic principles, motors, motor controllers, measuring devices, maintenance, troubleshooting, and safety show up in both. Even if your main interest is refrigeration, the Q803 electrical topics are not optional, and even if your main interest is the electrical plant, the shared fundamentals still count.

Side-by-Side Topic Comparison

The table below summarizes where the two published lists diverge. It is drawn directly from the NMC topic columns for the QMED02 endorsement.

Two things stand out. First, the modules are genuinely different in technical content, so preparing for one is not a free pass on the other. Second, even where a topic name looks similar, such as lubrication, it can be placed differently in each list, which is a reminder to study from the actual published headings rather than from memory of a similar-sounding rating.

Sequencing Your Study Around the Modules

General study methods are covered thoroughly in the QMED Study Guide, so this section is limited to how to order the content areas themselves. A module-aware sequence looks like this.

The logic is simple: shared topics first because they pay off in either module, signature topics next because they carry the module-specific difficulty, and shipboard systems last because they tie everything together. For a one-page recap near test day, the QMED Cheat Sheet condenses the must-know facts.

Where the Endorsement Gets Used

The QMED02 Electrician-Refrigerating Engineer endorsement is a merchant-marine credential, issued through the U.S. Coast Guard, and it is relevant to engineering department personnel aboard vessels where electrical distribution and refrigeration or air-conditioning plant must be maintained. That typically means employers that operate ships with substantial electrical and climate-control systems, and the mariners who staff their engine departments. The Q802 and Q803 headings read like a job description: keep the generation and distribution equipment healthy, keep motors and controllers working, keep refrigeration and air conditioning running, and do it safely.

For a closer look at the kinds of positions that draw on this endorsement, see QMED Jobs. For compensation and career value, the QMED Salary Guide and Is the QMED Certification Worth It? take that question on directly. To understand costs and logistics, read QMED Certification Cost and QMED Exam Dates, and to gauge difficulty, How Hard Is the QMED Exam? and QMED Pass Rate cover what is and is not known.

Turning the Topic Lists Into Practice

The most useful way to work with a topic list is to convert each heading into a question you can answer. For Q802, ask yourself whether you can explain how a motor controller changes the behavior of a motor, how a battery system differs from an A/C source in a troubleshooting scenario, and what the electrical safety implications are. For Q803, ask whether you can trace the refrigeration cycle, explain what a heat exchanger does in the plant, and identify the pipes, fittings, and valves that serve an air-conditioning or heating/ventilation system.

Then close the loop with practice. Working through realistic items on the QMED Exam Prep practice test site shows you which headings you actually know versus which only feel familiar. Because the exam scope is the NMC topic list rather than a weighted blueprint, every missed question maps back to a specific published heading, which makes gap review straightforward. If you are unsure how results are judged, QMED Passing Score addresses scoring, and the QMED Certification hub collects the rest of the credential background.

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