Commissioning levels are a five-stage scale, born in buildings and data centers, that orders testing from the factory to integrated operation: level 1, factory tests; level 2, receiving and site inspection; level 3, start-up and initial tests of each piece of equipment; level 4, full functional tests of each system; level 5, integrated testing of all systems together. It is not a standard: each project defines the content of each level.
Where the levels come from
In data center and critical facility projects, a way of ordering commissioning in five levels became popular, sometimes tied to colored tags hung on the equipment as it passes each stage. The idea is simple: no piece of equipment moves to the next level without passing the previous one, and the final level tests everything working together, failures included.
It is not a standard. ASHRAE Guideline 0 describes commissioning as a quality process that verifies and documents that the facility meets the owner’s project requirements, but the level scale is an industry convention. Sources agree on the general structure and differ in the details: some call level 2 “pre-installation” and others “SAT”; others add a design level 0 or intermediate levels. What matters is that each project writes down the definition of its levels and uses them as entry and exit gates.
The five levels
| Level | Usual name | Usual tag | What it includes |
|---|---|---|---|
| 1 | Factory testing | Red | Tests of each piece of equipment at the factory before shipping, often witnessed |
| 2 | Receiving and pre-installation | Yellow | Inspection on arrival at site against the specification, transport damage, storage and installation |
| 3 | Pre-commissioning and start-up | Green | Initial tests and first start-up of each piece of equipment, ready to connect to the system |
| 4 | Functional performance testing | Blue | Full test of each piece of equipment and system against its performance criteria |
| 5 | Integrated systems testing (IST) | White | All systems together, with simulated real conditions and failures |
Tag colors vary between sources and owners; the names in the table are the most common.
Their equivalent in substations and industry
The power sector does not speak of levels but of stages: factory tests, FAT, receiving, site tests, SAT, integration tests and energization. Those stages are described in pre-commissioning, commissioning and start-up and in substation commissioning. The mapping is direct:
| Level | In a substation or industrial plant |
|---|---|
| 1 | Routine tests of the transformer, switchgear and breakers; FAT of the protection, control and communications panels |
| 2 | Equipment receiving, transport impact recorders, installation inspection |
| 3 | Cold tests of each piece of equipment: primary tests, instrument transformers, wiring, secondary injection per relay |
| 4 | SAT of each system: protection with actual trips, controls and interlocks, point-to-point signal testing, end-to-end |
| 5 | Energization and integrated tests: transfers between sources, loss of the utility supply, generation start-up, operation under load |
IEC 62381, written for the automation systems of the process industry, distinguishes exactly the FAT, the SAT and the site integration test (SIT), which matches the idea of level 5. In a substation automation system (SAS), the same split appears as FAT of the panels, SAT per bay and integration with the control center.
- 01Level 1Factory and FAT
- 02Level 2Receiving and site inspection
- 03Level 3Cold tests per piece of equipment
- 04Level 4Functional SAT per system
- 05Level 5Integrated tests with real power
Why they reach electrical projects
The levels show up more and more in substation and plant specifications because data centers, hospitals and continuous-process industries buy the electrical side with the same logic as the rest of the facility. For the electrical contractor, that means its test reports must map to the owner’s levels: which test closes level 3 of a switchgear lineup, which document opens level 4 of the transfer system. In panels and MCCs, level 4 matches the functional tests of commissioning electrical panels and MCCs, and each level closes with its part of the commissioning dossier. If that mapping is agreed at the start, the electrical test schedule fits with the other disciplines and there are no arguments at the end about what was left untested.
Level 5 on the electrical side
Level 5 matters most to whoever designs the electrical side of a data center, a hospital or a plant with critical processes. Its typical test is the simulated loss of the utility supply: the service entrance is opened and the test verifies that the UPS units carry the load, that the generators start and pick up the load, that the automatic transfer switches act in the planned order and that everything returns to the utility when it is restored. Protection, transfer logic, the emergency generator and the control system all take part.
For that test to be safe and useful, the previous levels must be closed: protection with its approved settings, interlocks tested, panels verified and signals confirmed. A level 5 that uncovers a wiring error is a level 3 done badly.
How to use the levels when contracting
- Define each level in writing in the contract: which tests it includes, who performs them, who witnesses them and which document closes it.
- Use the levels as gates. No piece of equipment moves on with open nonconformities that affect it.
- Assign owners per level. The manufacturer usually answers for level 1; the electrical contractor and the testing company for levels 2 to 4; level 5 needs everyone.
- Do not confuse level with quality. A level 5 does not replace the primary or protection tests of the earlier levels.
The content of each level in a specific project depends on the owner’s specification and the product standards of each piece of equipment.
Levels 1 to 5 with Tiza Group
Our crew witnesses factory tests, performs the site tests of levels 2 to 4 and takes part in the integrated tests of the electrical side in substations, industrial plants and critical facilities, in Colombia, or elsewhere on request. Contact us about your project.
Related guides
- Pre-commissioning, commissioning and start-up
- Interlocking tests
- Point-to-point signal testing
- Commissioning dossier: test reports and as-built
- Substation commissioning: stages and tests
References
- ASHRAE Guideline 0-2019, The Commissioning Process.
- IEC 62381:2024, Automation systems in the process industry – Factory acceptance test (FAT), site acceptance test (SAT), and site integration test (SIT).
- ANSI/NETA ECS-2024, Standard for Electrical Commissioning Specifications for Electrical Power Equipment and Systems.
- CxPlanner, “Data centers and the commissioning process” (levels 1 to 5 and tags): https://cxplanner.com/commissioning-101/data-centers-level-testing
- Hioki, “Data Center Commissioning and 5 Levels of Testing”: https://www.hioki.com/id-id/industries-solutions/facilities/data-center-commissioning-levels.html
Frequently asked questions
What is level 5 commissioning?
It is integrated systems testing (IST): all systems operate together and real conditions and failures are simulated, for example loss of the utility supply, to prove that the UPS units carry the load, that the generators start and that the transfers act as designed.
Are commissioning levels a standard?
No. They are a convention of the building and data center industry. Sources agree on the five-level structure, but the names, the tag colors and the exact content of each level vary between owners and projects; some add a level 0 or additional levels.
How do the levels relate to FAT and SAT?
Level 1 corresponds to factory testing (FAT). The SAT and site commissioning are spread across levels 2 to 4, from receiving to the functional tests of each system. Level 5 corresponds to site integration testing, which IEC 62381 calls SIT.