Note
Before the Customer Inspects: What to Have Ready
The electrical work is done. The crew has left site. Your project manager calls the factory to schedule the formal acceptance walk-through. A date gets set for three days later.
What happens in those three days often determines whether the customer acceptance inspection takes two hours or two weeks to close.
The walk-through is not just a formality before the signature. For many Thai factory engineering teams, it is the moment they decide whether the work matches what was contracted. If the inspector walks in and finds missing documentation, measurements they cannot verify, or an open question about a material change nobody communicated, the walk-through stops being an inspection and becomes a negotiation. Getting it right means arriving prepared, not arriving first.
What does the customer’s engineer actually check?
The person leading the factory’s acceptance inspection is usually the electrical engineer or the facilities manager. Their role in the walk-through is specific:
- Installed equipment matches the contracted specification. Model numbers, quantities, and placement. If anything differs from the contract, they expect to see documentation explaining why.
- Workmanship is sound. Conduit fixed securely, cable dressing consistent, labels applied correctly, no exposed wiring, no visible damage to surfaces or equipment.
- Test records are complete and passed. For solar installations this includes string voltages and anti-islanding protection confirmation. For LED retrofits, illuminance measurements at agreed points.
- Documentation is present and organized. The handover file: as-built drawings, equipment datasheets, warranties, commissioning measurements, and any substitution records.
None of this is unexpected. The contractor’s job is to have all of it ready when the inspector walks in, not to assemble it while the inspection waits.
What stops a walk-through cold?
Four things reliably stall an acceptance inspection.
Missing measurements. The inspector asks for the commissioning lux readings. The file has photos of the finished installation but no measurement records. The technician who took the readings has the numbers in a chat thread on a phone that is now in another province. The walk-through pauses while the contractor tracks down a number that should have been attached to the job record the day it was taken.
Undocumented substitutions. The specified inverter was out of stock. The crew installed an equivalent model and told nobody in writing. The inspector compares the label on the wall to the contract spec and the model numbers differ. Without a substitution record showing customer approval and technical equivalence, the walk-through stops until the question is resolved.
No answer to a technical question. The inspector has a question about the protection relay settings. The person representing the contractor can carry documents but cannot answer a question about which setting was applied and why. A walk-through that stalls on a question the contractor could have prepared an answer to beforehand is a preparation failure, not a technical one.
Visible issues the contractor did not know about. A section of conduit has not been fastened at two points. The inspector notices it on the walk-through, notes it, and the question of what else might be missed enters the room. The same item on a pre-walk internal check would have been fixed before the date.
What to have ready before the walk-through starts
The window between “work done” and “walk-through scheduled” should produce one complete package the inspection runs from:
- The complete technical file: as-built drawing or marked-up plan, equipment datasheets for everything installed, warranty documents, serial numbers matched to installation locations
- Commissioning measurements, signed by the technician and dated on the day they were taken: string voltages and insulation test results for solar, lux readings by zone for LED
- Substitution records for any item that differs from the contracted specification, showing written customer approval obtained before installation started
- Test and inspection reports for any work requiring sign-off under Thai electrical installation standards, including protection test confirmation for grid-tied solar
- A current as-built markup showing anything that changed from the original drawing during installation, even minor routing changes
The person attending the walk-through on behalf of the contractor should be someone who can answer technical questions about the installation. Sending only a junior technician with a document folder puts the contractor at a disadvantage if the inspector has questions.
The day before the date, a contractor representative should walk the installation with the same checklist the customer will use. A conduit unfastened in a corner is a five-minute fix before the inspection and a noted item that shifts the tone if the customer’s engineer finds it first.
How do you handle a finding on the day?
Inspectors find things. That is the purpose of the walk-through. The question is how to respond.
A finding that can be resolved on the day with a factual discussion is not a problem. The inspector points at the substituted model. The contractor opens the substitution record showing the comparison and the customer’s written approval. The question is answered. The walk-through moves on.
A finding that requires physical work to resolve goes on a list. The contractor acknowledges it, agrees a remediation date, and the walk-through continues. The signature on the handover document waits until the remediation is confirmed. This is how the process is supposed to work.
What creates problems is pushing for the signature before remediation is complete, or responding to a finding with a verbal assurance that it will be fixed. Both situations produce conditional handovers that become contested when the remediation question surfaces again later. A short delay to fix something properly is a better outcome than a signed document with an outstanding item both parties remember differently.
FAQ
Should the acceptance walk-through happen before or after commissioning?
For solar installations, after commissioning: the protection tests need to be complete and documented before the inspector arrives, and the anti-islanding test result is part of the file the inspector reviews. For LED retrofits, after the lux measurements have been taken and attached to the job record.
What if the customer’s inspector is not available for two weeks after the work finishes?
The gap does not change the preparation. Use the time to assemble the complete file and confirm commissioning records are attached to the job record before the date arrives.
What if we disagree with a finding the inspector records?
Ask for it in writing: the specific item, the standard the inspector is applying, and what resolution looks like. This is not confrontational. It makes the follow-up conversation factual rather than a memory contest.
If your current process assembles the handover package in the days before the inspection rather than progressively as the job closes, there is a gap that can appear at the worst moment. The TRACE 30 program builds the file from commissioning through close, so the walk-through package exists before the date is set, not because of it. To talk through how this applies to the projects you run, schedule a call.