Introduction
If you work in electrical, instrumentation or mechanical roles across oil & gas, petrochemical, LNG, hydrogen, utilities or other hazardous industries, you've probably seen CompEx listed on job descriptions.
But what exactly is CompEx? Which qualification do you need? How long does it last? And is Ex01–Ex04 always the right course?
This guide explains the CompEx certification pathway in 2026 and helps energy professionals understand where each qualification fits.
What Is CompEx?
CompEx is an internationally recognised personnel-certification scheme designed to validate the competence of people working in potentially explosive atmospheres.
It was originally developed for the oil and gas sector but is now used across industries including petrochemical, chemical, maritime, pharmaceuticals, utilities, bioenergy and other environments where flammable gases, vapours, dusts or other explosion hazards may be present. CompEx qualifications are principally based around standards including the IEC 60079 and IEC 80079 series.
For employers, CompEx provides independent evidence that a worker has been assessed against defined hazardous-area competence requirements.
For candidates, it can be an important requirement for roles involving hazardous-area electrical or instrumentation equipment.
Why Is CompEx Important?
Hazardous areas can contain flammable gases, vapours or combustible dust.
Electrical or mechanical equipment used in those environments must be correctly selected, installed, inspected and maintained so that it does not become an ignition source.
That is why employers often look for personnel who understand:
- Hazardous-area classification
- Explosion-protection principles
- Ex equipment markings
- Installation requirements
- Inspection requirements
- Maintenance requirements
- Relevant standards
- Documentation and certification
Competence Assessment, Not Just Attendance
CompEx assesses those competencies rather than simply providing classroom attendance.
Who Typically Needs CompEx?
CompEx is especially relevant to:
- Electrical Technicians
- Electricians
- Instrument Technicians
- E&I Technicians
- Electrical Engineers
- Instrument Engineers
- Commissioning Technicians
- Commissioning Engineers
- Electrical Inspectors
- Instrument Inspectors
- Maintenance Technicians
- Hazardous-Area Inspectors
Mechanical Roles and CompEx
Some mechanical personnel may also require specific CompEx qualifications depending on their responsibilities.
What Is CompEx Ex01–Ex04?
Ex01–Ex04 is probably the qualification most energy professionals mean when they say "CompEx."
It is designed for competent electrical and instrumentation practitioners who install, inspect and maintain Ex-certified equipment in areas where explosive atmospheres may be created by gases or vapours.
The four units broadly cover:
- Ex01 – Preparation and installation of non-intrinsically safe Ex equipment
- Ex02 – Inspection and maintenance of non-intrinsically safe Ex equipment
- Ex03 – Preparation and installation of intrinsically safe equipment
- Ex04 – Inspection and maintenance of intrinsically safe equipment
What Ex01–Ex04 Assesses
Taken together, they assess both installation and inspection competence across common hazardous-area electrical systems.
What Will You Learn?
The official Ex01–Ex04 learning outcomes include understanding relevant IEC standards and hazardous-area requirements, recognising gas and vapour classifications and understanding different explosion-protection techniques.
Candidates typically cover topics such as:
- Hazardous-area zones
- Gas groups
- Temperature classes
- Equipment protection concepts
- Ex equipment certification
- Equipment markings
- Ex d flameproof equipment
- Ex e increased-safety equipment
- Ex i intrinsic safety
- Cable glands
- Installation requirements
- Inspection techniques
- Maintenance requirements
- Documentation
- Fault identification
Practical Competence Focus
The emphasis isn't simply on recognising equipment. Candidates must demonstrate that they understand how Ex equipment should be selected, installed and inspected in accordance with the relevant requirements.
How Long Is Ex01–Ex04?
The official CompEx information describes Ex01–Ex04 as typically a five-day programme.
That generally consists of around three days of guided theoretical and practical learning followed by two days of formal assessment. Some international centres offer an extended six-day version, particularly where additional language support is useful.
Training-centre schedules can vary, so candidates should always confirm the exact timetable before booking.
How Is CompEx Assessed?
Ex01–Ex04 includes both theoretical and practical assessment.
The current official structure includes a multiple-choice online examination and practical assessments covering each of the four units.
This is an important distinction.
CompEx isn't simply a course-completion certificate. Candidates must demonstrate competence during assessment.
What Are the Entry Requirements?
Ex01–Ex04 isn't intended as an introductory electrical course.
CompEx states that candidates should already be competent practising electricians, instrumentation technicians or people in similar technical roles. Engineers may also be eligible where they have relevant field experience involving hazardous-area installations.
Someone completely new to electrical or instrumentation work would normally be better suited to one of the foundation-level CompEx routes first.
CompEx Foundation – ExF
The CompEx Foundation qualification is aimed at people who need an understanding of hazardous areas but don't necessarily require full practitioner competence.
It can be relevant to:
- Trainees
- Newly qualified personnel
- Engineers
- Supervisors
- Designers
- Non-practising technical personnel
Foundation Focus
The focus is primarily theoretical.
For someone entering hazardous-area work for the first time, it can provide a useful introduction before progressing to practitioner-level qualifications.
CompEx Foundation Plus – ExF+
Foundation Plus adds practical learning to the foundation-level hazardous-area knowledge.
It's particularly useful for people who have technical backgrounds but are relatively new to Ex equipment and want more hands-on understanding before moving into practitioner-level certification.
CompEx's competency pathway positions ExF and ExF+ below its core practitioner qualifications.
CompEx Ex05–Ex06 – Combustible Dust
Not every hazardous atmosphere involves gas.
Industries such as the following can contain combustible dust:
- Food manufacturing
- Pharmaceuticals
- Biomass
- Waste processing
- Chemical production
- Grain handling
Dust-Hazard Qualifications
CompEx Ex05–Ex06 covers equipment used in environments where combustible dusts, fibres or flyings can create an explosion hazard.
These qualifications can be relevant to electrical and instrumentation personnel who install, inspect or maintain equipment in dust-hazard areas.
CompEx Ex11 – Mechanical
Explosion protection isn't purely an electrical issue.
Mechanical equipment can also create ignition sources through:
- Hot surfaces
- Friction
- Mechanical sparks
- Bearings
- Rotating components
- Static electricity
Who Needs Ex11?
CompEx Ex11 is aimed at mechanical operatives and engineers involved with equipment in gas, vapour or dust hazardous areas.
That makes it particularly relevant to some:
- Mechanical Technicians
- Mechanical Engineers
- Maintenance personnel
- Inspectors
- Rotating-equipment personnel
CompEx Ex12 – Application Design Engineer
Ex12 moves away from installation and maintenance and towards engineering design.
It's intended for professionals responsible for specifying electrical equipment and designing systems for hazardous areas.
Typical candidates might include:
- Electrical Engineers
- Instrument Engineers
- Design Engineers
- Hazardous-Area Engineers
- Project Engineers
CompEx Ex14 – Responsible Person
Ex14 is targeted towards senior personnel responsible for managing hazardous-area activities, people, procedures and compliance.
This may include:
- Engineering Managers
- Electrical Authorities
- Responsible Electrical Persons
- Supervisors
- Asset Managers
- Senior Engineers
Advanced Pathway Position
It sits towards the advanced end of the CompEx competency pathway.
Which CompEx Course Should You Take?
A useful way to think about the pathway is:
- New to hazardous areas → Ex Awareness / Ex Foundation
- Technical person wanting practical introductory knowledge → ExF+
- Practising Electrical or Instrument Technician → Ex01–Ex04
- Working in combustible-dust environments → Ex05–Ex06
- Mechanical practitioner → Ex11
- Hazardous-area design engineer → Ex12
- Responsible Person / senior management role → Ex14
Match the Course to Your Role
The correct qualification should ultimately be based on your actual job responsibilities, not simply which course appears most frequently in job advertisements.
Is CompEx Required Offshore?
Not automatically.
BOSIET and CompEx serve completely different purposes.
BOSIET prepares personnel for offshore safety and emergency situations.
CompEx demonstrates hazardous-area technical competence.
An offshore electrician or instrument technician may therefore require both, depending on the employer and role.
A general offshore worker may require BOSIET but have no need for CompEx at all.
Is CompEx Only for Oil & Gas?
No.
Although strongly associated with oil and gas, CompEx is now used across many industries where explosive atmospheres can occur.
Examples include:
- LNG
- Petrochemical
- Hydrogen
- Chemical manufacturing
- Pharmaceuticals
- Maritime
- Utilities
- Bioenergy
- Waste processing
- Fuel storage and distribution
Global Industry Use
CompEx says thousands of organisations worldwide use its scheme across a broad range of hazardous industries.
How Long Does CompEx Certification Last?
CompEx certificates are generally valid for five years.
Before expiry, practitioners must recertify if they want to maintain their certification.
For experienced Ex01–Ex04 practitioners who continue to work regularly in hazardous areas, CompEx offers the Recognised Practitioner Programme, Ex01RPP–Ex04RPP, as a shorter recertification route.
Other qualifications may require the original qualification to be undertaken again.
Can Employers Verify Your CompEx Certificate?
Yes.
CompEx provides an online verification service that allows employers and recruiters to check certificate information.
That's particularly useful within recruitment because hazardous-area competence is commonly a mandatory rather than desirable requirement.
Does CompEx Guarantee You a Job?
No certification can guarantee employment.
CompEx works best when combined with genuine trade or engineering competence.
Employers may consider:
- Electrical or instrumentation qualifications
- Relevant apprenticeships
- Industrial experience
- Hazardous-area experience
- Offshore experience
- Project experience
- CompEx certification
- Other role-specific certifications
Competence Still Comes First
Someone holding Ex01–Ex04 without meaningful electrical or instrumentation competence is unlikely to compete effectively with an experienced practitioner.
Careers Where CompEx Can Be Valuable
CompEx commonly appears against roles such as the ones below.
Electrical Technician — Installation, maintenance and fault-finding on electrical equipment within hazardous areas.
Instrument Technician — Installation, calibration, maintenance and inspection of instrumentation and control equipment.
E&I Technician — Combined electrical and instrumentation responsibilities across process plants and offshore facilities.
Commissioning Technician — Testing and commissioning electrical or instrumentation equipment before systems become operational.
QA/QC Inspector — Inspection and verification of hazardous-area installations against project and technical requirements.
Electrical Engineer — Design, technical support and engineering assurance of electrical systems.
Instrument Engineer — Engineering and specification of instrumentation and control systems.
Industries Where CompEx Can Improve Employability
The qualification can be particularly valuable in:
- Offshore Oil & Gas
- Refineries
- LNG
- Petrochemical
- Hydrogen
- Chemical Manufacturing
- FPSOs
- Offshore platforms
- Gas terminals
- Storage facilities
- Utilities
- Marine facilities
Can CompEx Increase Your Salary?
CompEx itself doesn't determine salary.
However, it can make candidates eligible for specialist hazardous-area roles that often attract stronger salaries or contract rates than general electrical or instrumentation positions.
The greatest value comes from the combination of trade competence, industry experience, hazardous-area experience and CompEx — rather than certification alone.
What Should You Check Before Booking?
Before paying for any CompEx course, confirm:
- Which CompEx units the employer requires
- Whether your current experience meets the eligibility requirements
- Whether the training centre is approved by CompEx
- Course duration
- Assessment dates
- What identification or evidence of competence is required
- Whether accommodation is included
- Whether resits involve additional fees
- Your existing certificate expiry date if recertifying
Confirm the Exact Qualification
Most importantly, don't automatically book Ex01–Ex04 because you've seen "CompEx required" on an advert.
Ask exactly which CompEx qualification is required.
CompEx and Your Career Pathway
For electrical and instrumentation professionals, CompEx can sit at an important point in career progression.
A potential electrical pathway might be: Electrical Apprentice → Electrician → Industrial Electrical Technician → CompEx Ex01–Ex04 → Hazardous-Area Electrical Technician → Senior Electrical Technician → Electrical Supervisor → Electrical Engineer / Electrical Authority.
Similarly for instrumentation: Instrument Apprentice → Instrument Technician → CompEx Ex01–Ex04 → E&I / Hazardous-Area Technician → Senior Instrument Technician → Commissioning Technician → Instrument / Commissioning Engineer.
Is CompEx Worth Getting in 2026?
If your target roles genuinely involve electrical, instrumentation or mechanical equipment in hazardous areas, CompEx can be an extremely valuable qualification.
But it should be viewed as a competency certification, not a shortcut into the industry.
The strongest candidates are those who already possess solid technical foundations and use CompEx to demonstrate specialist hazardous-area competence.
Before booking training, identify:
- The role you want.
- The industries you want to work in.
- The exact CompEx units those employers require.
- Whether you meet the entry requirements.
Avoid Unnecessary Training Costs
That approach can prevent you from spending money on training you don't actually need.
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