An inspection and test plan (ITP) turns requirements into controlled evidence. It states what is tested, when, by whom, with which instrument, against what criterion and what record authorizes release.
Learning objectives
Build a traceable ITP, define hold/witness/review points and ensure prerequisites are complete before energising test circuits.
Core engineering principles
Every test needs a source requirement
Contract clause, approved drawing or standard reference prevents arbitrary acceptance criteria.
Responsibilities must be explicit
Manufacturer, customer and third-party roles for perform, witness, review and approve should be stated.
Hold and witness points differ
A hold point stops work until release; a witness point can proceed after defined notice if the witness does not attend, subject to contract.
Prerequisites control safety and validity
Approved revisions, calibrated instruments, completed routine tests and energisation permits should be verified first.
Records are planned outputs
Each line should name the report, checklist, file or photograph that proves completion.
Engineering application method
- Step 1: Extract requirements from contract and standards.
- Step 2: Create test sequence and prerequisites.
- Step 3: Assign responsibility and intervention point.
- Step 4: Specify method, instrument and acceptance criterion.
- Step 5: Define report identity and release signature.
Practical example
“Check wiring” is not an ITP line. “Perform point-to-point continuity against schematic Rev.06; record deviations on checklist LVC-FAT-04” is testable and traceable.
Common mistakes
- Writing criteria as “OK”.
- Leaving document revision undefined.
- Using hold and witness interchangeably.
- Omitting calibration requirements.
- Planning records after the test.
Design and review checklist
- Does every line cite a requirement?
- Are roles and intervention points clear?
- Are prerequisites defined?
- Is acceptance objective?
- Is the output record named?
Standards basis and official sources
- IEC 62271-200:2021 + AMD1:2024 — AC metal-enclosed switchgear assemblies above 1 kV and up to 52 kV.
- IEC 61439-1:2020 — General rules for low-voltage switchgear and controlgear assemblies where applicable.
- IEC 60255-1:2022 — Common requirements for measuring relays and protection equipment.
Engineering note: Verify the contracted standard edition, amendments, manufacturer evidence and project-specific studies before applying these principles to a supplied assembly.