Entry & progression
Governing: MSN 1861 Amendment 1, sections 6.2-6.4; MSN 1904, sections 6 and 6.7; STCW Code Table A-III/1. Builds on: your EOOW electrical knowledge.
The definition that matters
The MCA definition (MSN 1861 A1 and MSN 1904):
A high voltage (over 1000 V) system is one where the voltage is generated and distributed at high voltage, or stepped up to high voltage and then distributed. It does not include systems where high voltage is used locally, for example ignition systems, radio transmission, radar and other navigational equipment.
COSWP 2026 uses the same threshold for safe working: HV equipment is equipment "designed to operate at a nominal system voltage in excess of 1000 volts". For small commercial vessels, MIN 724 points to IEC 60038 for the definition.
So a yacht with a 690 V main switchboard is not an HV ship, even if its radar has a kilovolt magnetron supply. A yacht whose generators feed an HV switchboard, or which steps up to HV to feed propulsion motors, is.
The limitation
If you do not hold the relevant HV training, the MCA endorses your CoC:
"This certificate is not valid for service on ships fitted with High Voltage (over 1000V) systems."
| CoC | HV course | STCW reference |
|---|---|---|
| SV EOOW (III/1) | HV Operational: optional (MSN 1904) | A-III/1 |
| SV Chief Engineer <500 GT / <3000 GT (III/3, III/2) | HV Management: optional (MSN 1904) | A-III/2 |
| Unlimited EOOW (III/1) | HV Operational, or qualifying HV sea service on revalidation | A-III/1 |
| Unlimited Second / Chief Engineer (III/2, III/3) | HV Management | A-III/2 |
"Optional" means you choose whether to accept the limitation. On a yacht market where some of the largest vessels run HV plants, that choice narrows the jobs you can take.
What STCW asks for
Operational (A-III/1): under "Operate electrical, electronic and control systems", the EOOW must know the basic configuration and operating principles of electrical equipment including high-voltage installations. MSN 1861 Annex B lists the operational topics:
- hazards of HV systems;
- functional, operational and safety requirements of a marine HV system;
- basic arrangement of HV systems and their protective devices;
- safety procedures;
- immediate actions under fault conditions.
Management (A-III/2 and B-III/2): adds assigning qualified personnel, producing a switching strategy, selecting isolation and test apparatus, carrying out switching and isolation with safety documentation, remedial action during faults, and insulation resistance and polarization index testing (L3.2).
Approved courses
The course must be run by an MCA-approved provider. The MCA keeps separate approved-provider lists for HV Operational and HV Management on its ATP page. The management course is taken by second and chief engineers and ETOs; provider pages describe it as a practical course of several days on a working HV training rig (L3.2).
CAUTION — The certificate is not an authorisation Holding an HV course certificate does not make you an authorised person on your yacht. Authorisation is given in writing by the company or chief engineer under the SMS, for that installation (L2.1).
For the wider electrical syllabus see the Yacht ETO programme; for revalidation rules see Keeping Your CoC Valid.