Periodic inspection, sampling and condition reporting (EICR)
Purpose and extent
A periodic inspection determines whether an installation is safe for continued use and produces an Electrical Installation Condition Report. Agree the extent and limitations with the client before starting: what will be inspected, what will be sampled, what cannot be accessed, and what will be isolated. Record the limitations on the report - they protect both parties.
Sampling
BS 7671 does not set a percentage. GN3 guides you to a sample of the installation - commonly around 10% of circuits, with a minimum in small installations - chosen to represent the different circuit types and ages. If the sample reveals defects, widen it; if it is clean, the sample stands. Bonding, earthing and the origin are always checked.
Classification
C1 - danger present, risk of injury, immediate action required; report at once and make safe with agreement. C2 - potentially dangerous, urgent remedial action required. C3 - improvement recommended. FI - further investigation required without delay. Any C1 or C2 makes the report unsatisfactory; C3 and FI do not automatically do so. The report states satisfactory or unsatisfactory, never pass or fail.
Trap: classifying a dangerous defect as C3 to keep the report satisfactory.
Trap: omitting limitations because the client wants a clean report.
Rule of thumb: C1 or C2 equals unsatisfactory, full stop.