How to plan commissioning and energisation as staged tests on a Gantt chart
Plan commissioning and energisation as staged tests on a Gantt chart: factory and site acceptance, the wait for energisation, grid-live tests, with each stage gating the next and retests allowed for in the duration.
Commissioning is a sequence of tests, and each one can only start when the one before it has passed and the equipment is in the right state. This guide shows how to lay those stages out on a Gantt chart so the last tests, which need a live connection, sit where they really belong.
The short version
- Give factory acceptance, site acceptance and grid-live tests their own tasks, in the order they can happen.
- Mark energisation as a milestone and make every test that needs a live connection depend on it.
- Plan the wait for the energisation approval as a task with a length, not as a gap.
- Allow for retests in the duration of a test task, and keep the test, fail, fix, retest loop in a flowchart.
- A timeline schedules testing; it does not make anything safe, certified or compliant.
Tests that gate each other
On many energy projects the build looks finished well before the project is. What remains is a chain of tests: a factory acceptance test before the equipment ships, a site acceptance test once it is installed and connected, an approval to energise, and then the checks that can only be done with the system live. Each stage gates the next. A plan that shows commissioning as one bar called "Testing" hides the order, and with it the reason the end date moves when one stage slips.
The method is to give every test stage its own task and to say what it waits for. The factory test waits for the equipment to be built. Delivery waits for the factory test. The site test waits for installation. Energisation waits for the site test and for the approval you do not control. The grid-live tests wait for energisation, because they need a live connection and cannot be brought forward. Put the approval wait in as a task with a length, and mark the moment of energisation as a milestone of length 0, so the tests that follow it have something to depend on.
A test that fails is fixed and run again, and a Gantt chart cannot draw that loop. Nothing in the chart sends a task back. What you can do is give the test task a duration that allows for a retest, and say so in the task notes. That keeps the plan honest about the time without pretending to know how many times a test will be repeated. The loop itself, test, fail, fix, retest, belongs in a flowchart, and the companion chart below shows one.
A timeline schedules the work. It does not make an installation safe, permitted, certified or compliant with any grid code, and it says nothing about how long a utility or an authority will take. Those are decisions for the people responsible for them. The durations in the example are illustrative; replace them with the times you are given.
A battery storage project, tested in stages
Twenty-two tasks and four milestones in four groups. Durations are illustrative; set your own. Open the spreadsheet panel to see the rows behind each stage.
Waits outside the project
"Wait for the utility connection study" (20 working days) follows "Submit grid connection application" (3) and leads to the "Connection offer accepted" milestone. "Wait for the authority permit review" (20) follows "Prepare and submit permit applications" (6). "Draft safety and fire strategy" (6) leads to the "Fire strategy signed off" milestone.
Factory test before delivery
"Battery enclosure manufacturing queue" (40) and "Power conversion unit manufacturing queue" (35) both feed "Run factory acceptance test" (5). "Deliver equipment to site" (5) waits for that test and for "Fire strategy signed off", which starts three days after "Freeze battery and inverter specification" starts.
Site works and installation
"Mobilise site and pour foundations" (12) waits for the permit review. "Build grid connection works" (15) starts five working days after it starts and also needs "Connection offer accepted". "Install enclosures and connect cabling" (8) waits for the foundations and for delivery.
Site test and the wait for energisation
"Run site acceptance test" (5) follows installation. "Wait for utility energisation approval" (8) waits for that test and for "Build grid connection works". The 5 days of the test are where you would allow for a retest, and the wait is a task with its own length.
Energisation, then the live tests
"Battery energised" is a milestone of length 0. "Run grid-live tests and performance run" (10) can only start after it, because those checks need a live connection. "Commercial operation" follows. This tail is always the last stretch of the critical path.
The test, fail, fix, retest loop a Gantt chart cannot draw
Fifteen steps with three decisions. This is the commissioning loop behind a single test task in the Gantt plan below.
Inspect, test and loop back on failure
After "Visual inspection of completed installation" comes "Continuity and insulation resistance testing" and the decision "Continuity and insulation test results pass?". A "Fail" goes to "Correct wiring fault and retest", which returns to the testing step.
Approval to energise
"Submit test results and request energization approval" leads to the decision "Energization approved by responsible engineer?". "Not approved" goes to "Hold energization, resolve outstanding issue" and back to the submission, so the wait has no fixed length.
Energise and test live
"Energize system under controlled conditions" leads to "Functional testing of energized system" and the decision "Faults found during functional testing?". "Yes" goes to "Diagnose and resolve fault" and back to the functional testing.
Report and hand over
With no faults, "Compile commissioning report" and "Hold handover meeting with customer" lead to "Commissioned system handed over to customer". In the Gantt chart each loop becomes extra days inside a test task.
How it works
List the test stages in the order they can happen
Write one task per stage: factory acceptance, site acceptance, the wait for energisation approval and the tests that need a live system. Do not combine them into a single bar called testing.
Say what each stage waits for
Fill in Depends on. The factory test waits for the manufacturing tasks, delivery waits for the factory test, the site test waits for installation, and the approval wait waits for the site test.
Mark energisation as a milestone
Add a task of length 0 for energisation. Make every test that needs a live connection depend on it, so it cannot be dated earlier than energisation.
Allow for retests in the duration
Add working days to each test task for a repeat, and write the assumption in the notes. A Gantt chart cannot draw a task returning to an earlier one, so the loop shows up only as length.
Fix a date only where it is fixed
If an energisation slot is genuinely fixed, give the wait task or the milestone a fixed Start. The chart flags the conflict if the dependencies cannot meet it, which shows early how much has to move.
Group, share and export
Group tasks into phases, put the responsible person in People, switch on View, Critical path to see which stage sets the finish, and share the chart or export a PDF for the project file.
Mistakes to avoid
Scheduling live tests before energisation
Checks that need a live connection cannot start earlier, however the plan looks. Make them depend on the energisation milestone so the chart cannot show them ahead of it.
Treating the approval wait as a gap
If the wait for energisation approval is left out, the live tests are dated straight after the site test. Plan it as a task with a length taken from what you are told, and revise it when you hear more.
Assuming every test passes first time
A plan with one pass of each test is the best case. Add days for a retest where failures are likely, and note the assumption so a reader does not take it for a prediction.
Reading a finished plan as a safe one
A chart where every test is dated says when the work is meant to happen. It does not show that the system is safe, permitted or certified, or that any authority will approve it by that date.
Open the battery storage Gantt chart
Open the battery storage template, change the test durations to yours and see the commissioning date move.
Related guides
Frequently asked questions
How do I show factory and site acceptance tests in a schedule?
Give each its own task. Put the factory test before delivery and the site test after installation, and link them with Depends on. Add a milestone for energisation after the site test and the approval wait.
Can a Gantt chart show a retest loop?
No. A Gantt chart cannot draw a task returning to an earlier one. Add working days to the test task for a repeat and write the assumption in the notes. A flowchart is the place to draw the loop.
How do I plan the wait for energisation approval?
As a task with a length in working days. Use the time you have been given as a placeholder and change it when you hear more. The tasks after it then move on their own.
Which test is on the critical path?
Switch on View, Critical path to light the chain that sets the finish date. In a plan like the example, the tests after energisation are usually at the end of that chain.
Where do I draw the commissioning procedure itself?
In a flowchart. The electrical system commissioning SOP at /templates/electrical-system-commissioning-sop draws the inspection, test, energisation and handover decisions. A Gantt chart can be duplicated as a flowchart and back.