Introduction
Commissioning is one of the most important stages of any major energy project.
Construction may be complete. Equipment may be installed. Cables may be terminated. Instruments may be connected.
But before a facility can enter operation, one critical question remains:
Does everything actually work — safely, correctly and as designed?
That is where commissioning comes in.
From oil & gas and LNG to offshore wind, power generation, nuclear, hydrogen, data centres and major industrial projects, commissioning professionals help take newly constructed or modified systems from construction completion to safe operation.
For experienced technicians and engineers, commissioning can also offer an attractive career route — particularly for professionals with strong backgrounds in Mechanical, Electrical, Instrumentation, Controls or Operations.
But how do you actually get into commissioning? What skills do employers look for? And what’s the difference between mechanical completion, pre-commissioning, commissioning and start-up?
This guide explains it.
Where Do You Fit?
A typical path from construction into live operations looks like this:
- Construction
- Mechanical Completion
- Pre-Commissioning
- Commissioning
- Start-Up
- Operations
What Is Commissioning?
Commissioning is the structured process of verifying and testing equipment and systems to demonstrate that they are installed correctly and operate according to the required design and performance criteria.
In simple terms:
- Construction builds it.
- Mechanical Completion checks it’s ready.
- Commissioning proves it works.
- Operations runs it.
Systems Thinking on Major Projects
On a major project containing thousands of individual components, that process can be extremely complex.
Rather than treating an entire facility as one unit, projects are commonly divided into systems and subsystems that can progressively move through completion, testing and handover.
This creates a controlled transition from construction into operations.
The Stages Before a Facility Goes Live
People sometimes use “commissioning” as a catch-all term, but several distinct phases may be involved.
1. Mechanical Completion
Mechanical Completion generally confirms that equipment and systems have been installed in accordance with the required drawings, specifications and project requirements and are ready to progress towards commissioning.
Activities may include:
- System walkdowns
- Inspection
- Punch listing
- Drawing verification
- Completion checks
- Test-pack review
- Documentation verification
- Systemisation
- Handover preparation
Mechanical Completion Focus
The focus is essentially: has it been built correctly and is it ready for the next stage?
2. Pre-Commissioning
Pre-commissioning prepares equipment and systems for functional commissioning.
Activities vary depending on discipline and system.
Mechanical Pre-Commissioning
- Cleaning
- Flushing
- Pressure testing
- Leak testing
- Equipment alignment
- Lubrication
- Rotational checks
Electrical Pre-Commissioning
- Cable testing
- Insulation resistance testing
- Continuity checks
- Protection testing
- Motor testing
- Transformer checks
Instrumentation Pre-Commissioning
At this point, teams are progressively demonstrating that individual equipment and systems are ready to operate.
- Calibration
- Loop checking
- I/O testing
- Control valve testing
- Instrument verification
3. Commissioning
Commissioning moves beyond individual installation checks and begins proving functional performance.
Depending on the facility, this may involve:
- System energisation
- Functional testing
- Equipment run tests
- Sequence testing
- Control system testing
- Cause-and-effect testing
- Interlock testing
- Emergency shutdown testing
- Safety system verification
- Integrated system testing
- Punch-list closeout
Why Multidisciplinary Understanding Matters
This is where multidisciplinary understanding becomes particularly valuable.
A problem may initially look electrical but actually originate from an instrument signal, control-system configuration or mechanical condition.
Commissioning professionals need to understand how systems interact, not simply individual pieces of equipment.
4. Start-Up
Start-up is where systems begin operating under real operating conditions.
For a process facility, that might involve introducing utilities and eventually hydrocarbons or other process materials.
For a power or renewable project, equipment may begin generating or transmitting power.
For a data centre, critical electrical, cooling and control infrastructure moves towards live operational service.
Commissioning teams often work closely with:
- Operations
- Maintenance
- Vendors
- Engineering
- HSE
- Client representatives
- Project management
Start-Up Objective
The objective is a safe, controlled transition into operation.
5. Handover
Once commissioning requirements have been satisfied, systems are progressively handed over to the organisation responsible for operating the asset.
Documentation becomes critical.
This can include:
- Test records
- Commissioning certificates
- Punch-list status
- As-built drawings
- Equipment records
- Vendor documentation
- Operating procedures
- Handover dossiers
Documentation Completes the Job
The project isn’t truly complete simply because the equipment works.
It must also be demonstrated and documented.
What Commissioning Roles Are There?
Commissioning isn’t one job.
Large projects can require multidisciplinary teams covering different systems and technical disciplines.
Mechanical Commissioning
Mechanical commissioning personnel may work with:
- Pumps
- Compressors
- Turbines
- Pipework
- Valves
- Pressure systems
- HVAC
- Rotating equipment
- Utility systems
Mechanical Commissioning Roles
Potential roles include:
- Mechanical Commissioning Technician
- Mechanical Commissioning Engineer
- Mechanical Commissioning Lead
Electrical Commissioning
Electrical commissioning professionals may work with:
- HV/LV systems
- Switchgear
- Transformers
- Motors
- Generators
- UPS systems
- Protection systems
- Distribution equipment
- Electrical control systems
Electrical Commissioning Roles
Potential roles include:
- Electrical Commissioning Technician
- Electrical Commissioning Engineer
- HV Commissioning Engineer
- Electrical Commissioning Lead
Instrument Commissioning
Instrumentation commissioning can involve:
- Pressure instrumentation
- Temperature instrumentation
- Flow measurement
- Level measurement
- Control valves
- Sensors
- Transmitters
- Loop checking
- Calibration
- I/O verification
Instrument Commissioning Roles
Potential roles include:
- Instrument Commissioning Technician
- Instrument Commissioning Engineer
- E&I Commissioning Technician/Engineer
Controls & Automation Commissioning
As facilities become increasingly automated, control systems play a major role during commissioning.
Professionals may work with:
- PLC
- DCS
- SCADA
- HMI
- Industrial networks
- Control logic
- Cause & effect
- Fire & Gas systems
- Emergency Shutdown systems
- Integrated control systems
Controls & Automation Roles
Roles can include:
- Control Systems Engineer
- Automation Commissioning Engineer
- ICSS Engineer
- PLC/SCADA Engineer
Completions & Systems Roles
Some careers sit across the technical disciplines.
These professionals help manage the transition of thousands of construction activities into structured systems ready for commissioning.
Roles can include:
- Completions Engineer
- Completions Coordinator
- Systems Engineer
- System Owner
- Mechanical Completion Engineer
- Punch List Coordinator
- Commissioning Coordinator
Organisation and Documentation
Strong organisation and documentation skills can be just as important here as technical knowledge.
What Skills Do Commissioning Employers Look For?
Job titles matter.
But in commissioning, specific experience and skills can matter even more.
Commonly relevant technical capabilities include:
- Mechanical Completion
- Systemisation
- System Walkdowns
- Punch Listing
- Loop Checking
- Electrical Testing
- Instrument Calibration
- Functional Testing
- Cause & Effect Testing
- Energisation
- Equipment Start-Up
- Fault Finding
- Control Systems
- P&ID interpretation
- Electrical drawings
- Technical documentation
- Handover
Professional Skills
Commissioning also requires:
- Problem-solving
- Communication
- Decision-making
- Coordination
- Safety awareness
- Technical reporting
- Interface management
- Leadership
Why Soft Skills Matter in Commissioning
Because commissioning sits at the point where construction, engineering, vendors, operations and the client all meet.
How Do You Get Into Commissioning?
This is one of the most common questions.
And there isn’t one single route.
Many commissioning professionals don’t begin their careers with the word “commissioning” in their job title.
They develop technical experience first.
For example: Electrical Apprentice → Electrical Technician → Electrical Commissioning Technician → Commissioning Engineer → Commissioning Lead.
Or: Instrument Technician → Instrument Commissioning Technician → E&I Commissioning Engineer → Commissioning Lead.
Or: Mechanical Technician → Mechanical Completion / Commissioning Technician → Mechanical Commissioning Engineer.
The exact route depends on qualifications, competence, industry and employer requirements.
Your First Commissioning Role
One of the biggest barriers candidates face is: “Every commissioning vacancy wants commissioning experience — so how do I get the first opportunity?”
The answer is often to look at the commissioning-related activities you’re already performing.
Have you participated in:
- Equipment installation checks?
- Testing?
- Loop checks?
- Energisation?
- Mechanical completion?
- Punch-listing?
- System walkdowns?
- Functional testing?
- Vendor testing?
- Start-up?
- Shutdown/restart activities?
- Handover?
Recognise Experience You Already Have
You may already have commissioning-relevant experience even if your job title has never included the word commissioning.
Don’t exaggerate it.
But don’t hide it either.
How to Show Commissioning Experience on Your CV
Compare these two descriptions:
“Electrical Technician on major oil & gas project.”
Versus: “Electrical Technician supporting mechanical completion and commissioning activities including HV/LV testing, motor checks, energisation, fault finding, system walkdowns and punch-list closeout.”
The second tells a recruiter significantly more.
Commissioning recruiters often search for activities, systems and equipment, not simply job titles.
Your CV should clearly show:
- What systems you worked on
- What equipment you tested
- Which commissioning activities you performed
- Which project phases you supported
- What level of responsibility you held
Skills-Driven Recruitment
This becomes particularly important as recruitment technology and CV search become more skills-driven.
What Certifications Do You Need for Commissioning?
There isn’t one universal “Commissioning Certificate” that qualifies someone for every commissioning role.
Requirements depend heavily on discipline, industry, location, project, employer and work environment.
Offshore Certifications
- BOSIET / FOET
- Offshore medical
- MIST where required
Hazardous Areas
Electrical and instrumentation personnel may require relevant hazardous-area competence such as CompEx, depending on the role and project.
Electrical Requirements
Requirements can vary significantly according to voltage level, location, responsibilities and local electrical regulations.
Safety Certifications
Depending on the environment, employers may request:
- IOSH
- NEBOSH
- Site safety training
- Permit-to-Work competence
- LOTO / isolation training
Choose Certifications Carefully
The important point is: check the actual requirements for your discipline and target project rather than collecting certifications simply because they appear on other people’s CVs.
Which Industries Need Commissioning Professionals?
Commissioning skills can potentially transfer across multiple industries.
These include:
- Oil & Gas — platforms, FPSOs, refineries, terminals and processing facilities
- LNG — liquefaction facilities, terminals and associated infrastructure
- Offshore Wind — substations, turbines, electrical systems and grid infrastructure
- Power Generation — gas, nuclear, conventional and renewable generation
- Hydrogen — electrolysers, processing equipment and associated infrastructure
- Data Centres — critical electrical, mechanical, controls and cooling systems
- Petrochemicals & Chemicals — complex process and control systems
- Major Industrial Projects — manufacturing, pharmaceuticals and other technically complex facilities
Why Cross-Sector Experience Matters
This cross-sector relevance is one reason commissioning can be an interesting long-term career.
Can Commissioning Skills Transfer Between Industries?
Yes — but don’t assume everything transfers automatically.
The fundamental commissioning process may be similar: Inspect → Test → Verify → Demonstrate → Handover.
But the systems, regulations and technical requirements can be very different.
For example, an Electrical Commissioning Engineer moving from oil & gas into data centres may understand HV/LV, switchgear, generators, UPS, protection, energisation and functional testing.
But may need to develop knowledge around data-centre-specific architecture, BMS/EPMS or Integrated Systems Testing.
The transferable skill is valuable.
The knowledge gap still matters.
What Makes a Strong Commissioning Professional?
Technical ability alone isn’t enough.
Commissioning frequently happens towards the end of a project when schedules are tight and multiple disciplines are competing to complete outstanding work.
Strong commissioning professionals need to be able to:
- Understand the system
- Identify what’s stopping it from progressing
- Work with the right people to resolve it
- Test it safely
- Document the result
- Move the system towards handover
Why Experienced Commissioning Personnel Are Valuable
That combination of technical knowledge, problem-solving and coordination is what makes experienced commissioning personnel valuable.
Where Can a Commissioning Career Take You?
Career progression can potentially include: Commissioning Technician → Commissioning Engineer → Senior Commissioning Engineer → Commissioning Lead → Commissioning Manager → Commissioning / Start-Up Manager → Project or Operations Leadership.
But progression doesn’t always mean management.
Some professionals build careers as highly specialised technical experts in areas such as:
- HV commissioning
- Controls
- Turbines
- Rotating equipment
- Protection systems
- ICSS
- Instrumentation
- Start-up
Specialist Routes Are Valuable Too
A specialist technical route can be just as valuable as a management route.
Follow Projects Before Commissioning Recruitment Peaks
This connects directly to understanding the project lifecycle.
Commissioning teams aren’t normally the first major workforce to arrive.
Before commissioning comes: Engineering → Procurement → Construction → Mechanical Completion.
As a project approaches the later stages of construction, commissioning requirements can begin increasing.
That means professionals interested in future commissioning opportunities should follow projects, not only vacancies.
Look at:
- What is being built?
- What stage has the project reached?
- Who is the EPC contractor?
- Which commissioning contractors are involved?
- When is mechanical completion expected?
- When is start-up planned?
Context Ahead of Vacancies
That can provide useful context about where future workforce requirements could emerge.
Explore Commissioning on Energy Recruitment Hub
Energy Recruitment Hub brings together different parts of the career journey.
Career Pathways — Explore commissioning roles, progression routes, skills and related careers.
Skills — Understand the individual technical capabilities connected to commissioning and other disciplines.
Project Finder — Follow major energy projects and understand where they sit in the project lifecycle.
Jobs — Browse current commissioning and energy opportunities.
CV Profile — Make your technical experience and skills easier to discover when relevant opportunities arise.
Rather than viewing these separately, think of them as connected: Project → Project Phase → Required Skills → Career Pathway → Candidate → Opportunity.
That’s the bigger picture.
Final Thoughts
Commissioning is the point where years of engineering and construction finally have to prove themselves.
A facility isn’t ready simply because it has been built.
It needs to be checked, tested, demonstrated and safely handed over.
That requires people who understand equipment, people who understand systems, and increasingly, people who understand how multiple disciplines work together.
For Mechanical, Electrical, Instrumentation, Automation and Operations professionals, commissioning can offer a route into some of the most technically challenging stages of major energy projects.
Your route into commissioning may not start with a new job title.
It may start by recognising the commissioning skills you already have.