What C1, C2, C3 and FI Actually Mean on an EICR

The Four Observation Codes Explained

The observation coding system in an EICR is defined by BS7671, the wiring regulations that govern electrical installation work in the UK. Each code describes the nature and urgency of a defect found during inspection and testing.

C1 — Danger Present

A C1 observation means danger is present and there is a risk of injury to persons or property. This is the most serious classification. When a C1 is recorded, the inspector is saying that the defect poses an immediate risk — things like exposed live conductors, a wiring fault that could cause electric shock under normal use, or a condition that creates a direct fire hazard.

A C1 automatically makes the EICR report Unsatisfactory. The expectation is that a C1 is remedied before the installation is put back into use, or that the circuit or equipment concerned is isolated until it can be repaired. In practice, if a C1 is discovered during inspection, your electrician may make it safe on the day before leaving the property.

C2 — Potentially Dangerous

A C2 observation means the defect is potentially dangerous — it does not present an immediate hazard under normal conditions, but given a particular circumstance (a fault elsewhere, an unusual load, water ingress, a specific use of the installation), it could become dangerous.

C2 observations also make the EICR Unsatisfactory. This is probably the most misunderstood aspect of EICR coding. Landlords sometimes receive a report with several C2 observations and assume that because nothing has gone wrong yet, the report is still acceptable. It is not. Any C2 observation results in an Unsatisfactory report, which in the context of the Private Rented Sector Regulations means remedial works must be carried out within 28 days (or sooner if specified).

Common C2 observations include lack of RCD protection in certain locations, inadequate earthing or bonding, deteriorated insulation resistance on older circuits, and protective conductors with incorrect sizing.

C3 — Improvement Recommended

A C3 observation is a recommendation — the inspector has identified something that does not meet current standards but does not present a danger under the current conditions. A C3 does not make the EICR Unsatisfactory on its own.

This is important. A report that contains only C3 observations can still be Satisfactory. C3 items are typically improvements that would bring the installation closer to the current edition of the wiring regulations, but they are not required to be remedied within any statutory timescale. Many older installations will carry C3 observations simply because they were installed to an earlier edition of the standard.

Typical C3 observations include older consumer unit designs that lack full RCD coverage, earth electrode resistance values that are acceptable but could be improved, or protective conductor cross-sections that meet the older standard under which they were installed but not the current one.

FI — Further Investigation Required

FI is used when the inspector cannot determine whether a defect is safe or not without additional investigation. Something has been found during the inspection or testing process that requires a closer look before the installation can be confirmed as safe.

An FI automatically makes the EICR Unsatisfactory, because the inspector cannot sign off the installation as safe while there is an unresolved question. FI observations often arise when testing reveals values that are outside normal ranges but the cause cannot be confirmed during the inspection visit — for example, an insulation resistance reading that is borderline, or a circuit that behaves unexpectedly during testing.

Further investigation may involve opening up the installation, tracing cables, or carrying out additional diagnostic tests. Once the investigation is complete, the observation can typically be reclassified as C1, C2, C3, or removed entirely if no defect is confirmed.

What Makes an EICR Satisfactory or Unsatisfactory?

The overall condition of the report — Satisfactory or Unsatisfactory — is determined by the worst observation code present. A single C1 or C2 makes the entire report Unsatisfactory, regardless of how many other aspects of the installation are in good condition. An FI also makes the report Unsatisfactory until resolved.

A report with only C3 observations, or with no observations at all, can be recorded as Satisfactory. This is worth understanding when you receive a report: Satisfactory does not mean perfect. It means no observations that currently render the installation dangerous or potentially dangerous were found.

What Landlords Need to Do When a Report Is Unsatisfactory

Under the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020, landlords must carry out remedial works within 28 days of an Unsatisfactory report (or sooner if the report specifies a shorter timescale for certain defects).

Once remedial works are complete, you should receive either a minor works certificate or a new EICR (depending on the scope of the work) confirming the installation is now Satisfactory. A copy of both the original Unsatisfactory report and the completion certificate should be provided to your tenant within 28 days and kept available for the local authority if requested.

• Provide a copy of the Unsatisfactory EICR to existing tenants within 28 days of receiving it
• Carry out remedial works within 28 days (or sooner if specified in the report)
• Obtain written confirmation that works are complete
• Retain copies of both the original report and the completion certificate
• Provide the completion certificate to tenants and keep it available for council inspection

A Note on Engineering Judgement

It is worth knowing that EICR coding is not always black and white. Two qualified inspectors looking at the same observation may sometimes apply different codes — particularly at the boundary between C2 and C3. This is not a sign of incompetence. It reflects the fact that the regulations require professional judgement to be applied in context, taking account of the type of installation, its age, how it is used, and the risk it presents in that specific environment.

If you receive an EICR with observations you do not understand, asking the inspector to explain their reasoning is entirely reasonable. A good electrician should be able to explain why they coded something as they did and what the risk actually is.