Which item serves as formal confirmation that commissioning activities have been completed and approved by the responsible authority?

• A. Test log only.
• B. Manufacturer literature.
• C. Insurance approval letter.
• D. Commissioning sign-off.

Answer: (D)

Commissioning sign-off is the formal confirmation that commissioning activities have been completed and approved by the responsible authority. It acts as the official record showing that all required tests and inspections were performed, results meet the criteria, and the system is approved for operation. A test log, while it documents tests and outcomes, does not itself certify acceptance. Manufacturer literature is just product information and guidance, not a sign of formal approval. An insurance approval letter concerns coverage, not the readiness or acceptance of the installation. So the commissioning sign-off best represents the formal acceptance of the completed commissioning work.