- What a QMED Actually Is
- Who Issues It and Where the Exam Comes From
- Two Modules: Electrician (Q802) and Refrigerating Engineer (Q803)
- What the Q802 Electrician Module Covers
- What the Q803 Refrigerating Engineer Module Covers
- The Shared Core Both Modules Test
- How QMED02 Differs From Other Engine-Department Ratings
- Where This Rating Gets Used
- Sequencing Your Preparation
- Frequently Asked Questions
- This QMED is the U.S. Coast Guard National Maritime Center's QMED02 Electrician-Refrigerating Engineer endorsement.
- The exam is organized as two modules: Q802 Electrician and Q803 Refrigerating Engineer.
- The two modules are topic lists, not percentage-weighted blueprint domains.
- Q802 leans on A/C and D/C circuits, motors, controllers, generation and distribution; Q803 leans on refrigeration, heat exchangers and HVAC.
What a QMED Actually Is
On a merchant vessel, "QMED" is shorthand for a Qualified Member of the Engine Department: a rated crew member who works in the engine room below the licensed engineers. The specific endorsement this article covers is QMED02, Electrician-Refrigerating Engineer. It is a rating in the engine department, and it centers on the electrical plant and the refrigeration and air-conditioning systems that keep a ship, its cargo and its crew running.
If you are searching for "what is a QMED" and you work or plan to work aboard U.S.-flag vessels, this is the credential you are looking at. It is not a generic engine-room title. It is a defined endorsement with a defined examination, and the exam content is published by the federal agency that regulates mariner credentials. If you want companion explainers on the terminology itself, see What Is QMED?, What Does QMED Stand For? and QMED Meaning.
Who Issues It and Where the Exam Comes From
The governing body is the United States Coast Guard National Maritime Center (NMC). The NMC publishes the exam information for the QMED02 Electrician-Refrigerating Engineer endorsement, including the two module designations (Q802 and Q803) and the topic lists that define what a candidate can be tested on. Those topic lists are the single most reliable map of the exam, and every serious study plan should be built from them rather than from rumor or old crew-room advice.
One practical consequence: the published material describes topics, not a scoring blueprint with percentage weights. You will not find a statement such as "this subject is a fixed share of your exam." That is why this guide treats the two modules as scope areas to master rather than as slices of a pie chart. For the structure in more detail, read our QMED exam domains guide.
For eligibility, documentation and how to qualify, use our QMED requirements guide; for pricing, see the certification cost breakdown. Always confirm current administrative details directly with the NMC, since this article only states facts drawn from the published exam topic material.
Two Modules: Electrician (Q802) and Refrigerating Engineer (Q803)
The endorsement is examined through two modules that mirror the two halves of the title:
| Module | Focus | Distinctive subject areas |
|---|---|---|
| Q802 Electrician | The ship's electrical systems, from generation to end-use equipment | A/C circuits, D/C circuits, batteries, generation equipment, distribution systems, communication devices, steering, deck machinery |
| Q803 Refrigerating Engineer | Refrigeration, air conditioning and heating/ventilation plant | Refrigeration principles, heat exchangers, hydraulic principles, pipes, fittings and valves, air conditioning, heating/ventilation |
Think of the two modules as overlapping but not identical. Both draw on a common base of general engine-room knowledge, electrical fundamentals and safety. Each then adds its own specialist layer. A candidate who thinks of QMED02 as "just electrical" will be caught off guard by the refrigeration and HVAC side, and the reverse is equally true.
What the Q802 Electrician Module Covers
The published Q802 topic list is long, and the electrical heart of it is easy to identify. The module is where you demonstrate that you understand how electrical power is made, moved, controlled and protected aboard ship.
Electrical Core (Q802)
These are the subjects that most directly define an Electrician's knowledge:
- A/C circuits and D/C circuits: the fundamentals behind everything else on the list.
- Generation equipment and distribution systems: how power originates and reaches loads.
- Motors and motor controllers: the equipment you will troubleshoot most often.
- Batteries: emergency and starting power.
- Calculations, electronic principles, measuring devices: the quantitative and instrument side of the work.
- Troubleshooting, maintenance, safety: applying the above to a failing system.
- Communication devices: shipboard signaling and communication equipment.
Machinery and Shipboard Systems (Q802)
Q802 also reaches into mechanical territory an electrician is expected to understand:
- Auxiliary machinery, deck machinery and steering
- Pumps, fans, and blowers
- Bearings, lubrication and compressed air
- Remote control equipment and instrumentation principles
- Measuring instruments, drawings and tables
- Use of hand and power tools, care of equipment and machine parts, maintenance procedures
Notice how much of this is applied rather than theoretical. A question about a motor controller is really a question about how a circuit behaves and what you would check when it does not. Candidates who have only memorized definitions tend to struggle with that kind of reasoning; those who have worked with the equipment, or who practice scenario-style questions, are better positioned. Our difficulty guide discusses what makes this exam demanding.
What the Q803 Refrigerating Engineer Module Covers
Q803 swaps the generation-and-distribution emphasis for thermal and fluid systems. It is the module for people who keep provisions cold, cargo conditioned and spaces habitable.
Refrigeration and Climate Systems (Q803)
- Refrigeration principles and refrigeration systems: the cycle, components and operating behavior.
- Air conditioning and heating/ventilation: comfort and environmental control plant.
- Heat exchangers: how heat is transferred in condensers, evaporators and related equipment.
- Hydraulic principles: fluid behavior that underlies pumps, circuits and controls.
- Pipes, fittings, and valves: the plumbing of the plant, and how to read and service it.
Supporting Subjects (Q803)
- Auxiliary machinery, pumps, fans, and blowers, bearings, lubrication principles
- Electrical, electronic principles, motors, motor controllers, measuring devices
- Remote control equipment, instrumentation principles, measuring instruments
- Maintenance, troubleshooting, drawings and tables, hand and power tools
- Pollution prevention and compressed air
The electrical entries in Q803 matter more than people expect. Compressors and fans are driven by motors, and those motors are started and protected by controllers. A refrigerating engineer who cannot reason about motor circuits will be exposed. That cross-dependence is exactly why the two modules are packaged into one endorsement.
Key Takeaway
Do not study Q802 and Q803 as isolated silos. Motors, motor controllers, measuring devices, troubleshooting and electronic principles appear in both published lists, so a strong electrical foundation lifts your performance in both modules.
The Shared Core Both Modules Test
A large portion of the published topic lists is common to both modules. This shared material falls into three clusters.
General Engine-Room Knowledge
Both modules list general subjects, auxiliary machinery, bearings, care of equipment and machine parts, drawings and tables, instrumentation principles, maintenance procedures, measuring instruments, pumps, fans, and blowers, remote control equipment, and the use of hand and power tools. This is the vocabulary and judgment of the engine room itself.
Safety and Environmental Protection
Both modules include a substantial safety block: communications, damage control, elementary first aid, emergency equipment, environmental awareness, fire prevention, firefighting equipment, firefighting principles, general safety and hazardous materials. Pollution prevention appears in the general subjects of each module as well. These are not throwaway topics. They represent the habits that keep a vessel and its crew out of trouble, and they reward candidates who have actually drilled these procedures.
Shipboard Equipment and Systems
Each module has a shipboard-systems section. For Q802 it names compressed air, lubrication and steering. For Q803 it names air conditioning, compressed air, heating/ventilation and refrigeration. This is where the exam ties the specialty back to the physical ship.
How QMED02 Differs From Other Engine-Department Ratings
The NMC publishes separate exam material for the engine-department ratings, and QMED02 is its own endorsement. Its published scope is the Electrician and Refrigerating Engineer modules specifically. It is not the same endorsement as Junior Engineer, Oiler, Boiler Technician-Watertender or Machinist-Pump Technician.
This matters for two reasons. First, general "QMED" study material that blends all the ratings together will contain content that does not apply to you and may miss content that does. Generic QMED material alone does not replace this rating's own scope, so anchor your preparation to the Q802 and Q803 topic lists. Second, when you read forum posts or talk to shipmates, check which rating they are describing before trusting their advice about what is "on the test."
For a deeper look at the terminology, our explainers What Does QMED Mean?, What Is QMED Certification? and the overview at QMED Certification are good companions to this one.
Where This Rating Gets Used
The QMED02 endorsement is a seagoing credential, so the employers who care about it operate vessels with electrical plants and refrigeration or climate-control systems that need a qualified rating to maintain them. In practice that means companies operating U.S.-flag merchant vessels, where the engine department includes rated members who hold endorsements like this one. The endorsement signals that you have been examined on the electrical and refrigeration/HVAC systems that such ships depend on.
The duties implied by the topic lists give you a clear picture of the day-to-day: keeping generators and distribution gear healthy, troubleshooting motors and controllers, maintaining batteries, servicing refrigeration and air-conditioning plant, and following the safety and pollution-prevention practices that govern all of it. For a view of the market, see our pages on QMED jobs, the salary guide and the ROI analysis. We do not quote earnings figures in this article because the published exam sources do not provide them.
Sequencing Your Preparation
Since the exam is a topic list rather than a weighted blueprint, a sensible plan front-loads the material that serves both modules, then specializes. The outline below ties the order to the QMED02 scope rather than to generic technique.
Shared safety and general subjects
- Firefighting principles and equipment, damage control, hazardous materials, first aid
- Pollution prevention and environmental awareness
- Drawings and tables, measuring instruments, hand and power tools
Electrical fundamentals (both modules)
- D/C and A/C circuits, calculations, electronic principles
- Motors and motor controllers, measuring devices
- Troubleshooting method applied to motor and control faults
Module specialization
- Q802: generation equipment, distribution systems, batteries, communication devices, steering
- Q803: refrigeration principles, heat exchangers, pipes, fittings, and valves, air conditioning, heating/ventilation
Machinery and review
- Pumps, fans, blowers, bearings, lubrication, compressed air
- Timed practice questions across every published topic
Adjust the order to your background. A shipboard electrician may need extra time on heat exchangers and hydraulics if sitting Q803; a refrigeration technician may need extra time on A/C circuits and distribution for Q802. For a full plan, see the QMED study guide and the one-page cheat sheet, and when you are ready to test your recall, take a timed run on the QMED practice test. Our QMED training page covers structured preparation options.
Key Takeaway
Build your checklist directly from the NMC's published Q802 and Q803 topic lists, tick off the shared subjects first, then drill your specialty module with practice questions on the main practice test site.
Frequently Asked Questions
It is the QMED02 Electrician-Refrigerating Engineer endorsement, a rated engine-department credential whose exam content is published by the U.S. Coast Guard National Maritime Center. For more variations of the question, see What Is A QMED?
Q802 Electrician and Q803 Refrigerating Engineer. They are examination modules defined by published topic lists, not percentage-weighted blueprint domains.
No. Oiler, Junior Engineer, Boiler Technician-Watertender and Machinist-Pump Technician are separate engine-department ratings with their own published exam material. QMED02 is specifically the Electrician-Refrigerating Engineer endorsement.
Both cover safety and environmental protection, firefighting, damage control, first aid, pollution prevention, machinery care, instrumentation, measuring instruments, motors, motor controllers, electronic principles, maintenance and troubleshooting.
This article sticks to facts from the published topic material. For scheduling, scoring and fees, see our guides on exam dates, the passing score, the pass rate and certification cost, and confirm current details with the National Maritime Center.