What Do C1, C2, C3 and FI Mean on an EICR?

If you have received an Electrical Installation Condition Report, the codes C1, C2, C3 and FI explain how serious each observation is and what should happen next. In simple terms, C1 means danger is present, C2 means potentially dangerous, C3 means an improvement is recommended, and FI means further investigation is advised.

A report containing a C1 or C2 observation will be marked unsatisfactory. C3 does not make the report unsatisfactory. Under the current BS 7671:2018+A4:2026 report wording, FI does not make it unsatisfactory either, although it should not simply be ignored.

This guide explains what the codes mean, how they affect the result and why the code alone does not necessarily tell you the cost or extent of the work required.

What is an EICR classification code?

An Electrical Installation Condition Report (EICR) assesses whether the fixed electrical installation in a home or commercial property appears safe for continued use. When an inspector finds an issue, it is recorded as an observation and assigned a classification code according to the level of danger or urgency.

The code is not a quotation and it is not a complete repair specification. It communicates the inspector’s safety assessment at the time of the inspection. The context matters: the same visible feature may receive a different outcome depending on its location, condition, how it is being used and what protection is already in place.

What does a C1 code mean on an EICR?

C1: Danger present — immediate remedial action required

A C1 is the most serious EICR classification. It means there is a danger present at the time of the inspection and a risk of injury. An example could be an accessible live part that somebody could touch.

Where possible, the inspector may take immediate action to remove the danger before leaving, such as safely isolating the affected circuit. That does not necessarily complete the permanent repair, but it can prevent the installation continuing to present an immediate risk.

A single C1 observation makes the EICR unsatisfactory. It should be dealt with immediately, not left until the next planned maintenance visit.

What does a C2 code mean on an EICR?

C2: Potentially dangerous — urgent remedial action required

A C2 means the inspector has identified a condition that is potentially dangerous, even though it may not present the same immediate danger as a C1 at that moment. Urgent remedial action is required.

Possible examples include inadequate protection against electric shock in circumstances where danger could arise, damaged equipment or a defect that could become hazardous under fault conditions. These are only broad examples: the correct classification depends on the installation and the inspector’s professional judgement.

A single C2 observation also makes the EICR unsatisfactory. A C2 should not be dismissed because the lights and sockets still appear to work normally.

What does a C3 code mean on an EICR?

C3: Improvement recommended

A C3 records an improvement that would enhance the safety of the installation but is not considered dangerous or potentially dangerous in its present condition. A C3 observation does not make the report unsatisfactory.

This distinction is important because an older installation does not automatically fail an EICR simply because it was installed to an earlier edition of the Wiring Regulations. The purpose of an EICR is to assess safety for continued use, not to insist that every existing installation is rebuilt to the latest standard.

For example, the IET explains that a plastic consumer unit does not automatically warrant a classification code merely because current domestic consumer units are generally non-combustible. Its position and the surrounding risk can change the assessment. If your report recommends an upgrade, our guide to fuse board and consumer unit replacement explains what is involved.

What does FI mean on an EICR?

FI: Further investigation advised

FI is used when the inspection or testing reveals a possible safety issue but the inspector cannot determine its cause or full significance within the agreed scope of the EICR. Finding the cause may require separate diagnostic or electrical fault-finding work.

FI should not be used as a vague substitute when the inspector already has enough information to assign an appropriate C1, C2 or C3 code. In domestic installations, it should generally be possible to classify most observations without resorting to FI.

The FI rules changed in 2026

There is an important difference between older EICR forms and reports produced using BS 7671:2018+A4:2026. Previously, FI meant further investigation was required without delay and it affected the overall result. Under Amendment 4, the wording is further investigation is advised, and an FI observation does not by itself make the report unsatisfactory.

That is why apparently conflicting explanations can be found online. If you are looking at an older report, check which edition is stated on it and ask the inspecting electrician to explain how its FI observation affects the recorded outcome.

Which EICR codes make a report unsatisfactory?

C1 and C2 observations result in an unsatisfactory EICR. Under the current Amendment 4 report format, C3 and FI are advisory and do not alter the overall result to unsatisfactory.

“Unsatisfactory” does not necessarily mean the entire property needs rewiring. It means one or more observations affecting the safety assessment require appropriate remedial action. The solution might be a focused repair, additional protection, replacement of an accessory, work at the consumer unit or, in some installations, more extensive work.

Does a C2 mean the house needs rewiring?

No. A C2 describes the urgency of a particular safety observation; it does not prescribe a full house rewire. One property may need a relatively contained repair, while another may have several defects caused by deteriorated or unsuitable wiring.

The electrician should explain the observation, identify the affected part of the installation and specify the work needed to address it. If defects are widespread, Gabe Electrical’s guide to full and partial house rewiring explains the difference between repairing individual circuits and replacing a larger part of the installation.

Can you ignore a C3 because the EICR is satisfactory?

A C3 does not cause an EICR to be marked unsatisfactory, but that does not mean it has no value. It is a professional recommendation intended to improve the installation. Consider the reason for the recommendation, the age and use of the property, and whether other work is already planned.

Some C3 improvements can be sensibly combined with renovation, a consumer unit upgrade or other electrical work. Ask the electrician to explain the practical benefit, priority and likely disruption rather than treating every C3 as equally urgent.

What should you do after receiving your EICR?

If the report contains a C1

Treat it as an immediate safety matter. Confirm whether the danger was made safe during the inspection and arrange the permanent remedial work without delay.

If the report contains a C2

Arrange urgent remedial work. Ask for a clear explanation of the affected circuit or equipment and what must be done to remove the potentially dangerous condition.

If the report contains a C3

The report can still be satisfactory. Discuss the benefit and sensible timing of the recommended improvement, particularly if other electrical or renovation work is planned.

If the report contains FI

Do not assume that “advisory” means unimportant. Ask what prompted the FI observation, what further work is recommended and whether the report was produced using the current Amendment 4 format or an earlier one.

Why the written observation matters as much as the code

A useful EICR should do more than display a string of codes. Each observation should be clear enough for the person ordering the report—and an electrician carrying out subsequent work—to understand what was found and where.

The quality and scope of the original inspection matter too. Our article on how much gets tested during an EICR explains why access, agreed limitations and the amount of inspection and testing can vary. If you are still comparing quotations, see our guide to EICR costs in Cardiff.

EICR codes: frequently asked questions

Is an EICR with only C3 observations satisfactory?

Yes. C3 means improvement is recommended and does not make the report unsatisfactory.

Can one C2 make the whole EICR unsatisfactory?

Yes. One C1 or C2 observation is enough for the overall assessment to be unsatisfactory.

Does an unsatisfactory EICR mean the electricity must be switched off?

Not automatically. A C1 danger may require immediate isolation or other action to make it safe. With a C2, the appropriate response depends on the defect and the inspector’s assessment. Follow the instructions given by the inspecting electrician.

Does FI make an EICR unsatisfactory?

On an EICR produced using BS 7671:2018+A4:2026, no: FI is advisory and does not by itself make the report unsatisfactory. Older report formats treated FI differently, so check the edition stated on the report.

Need help understanding an EICR in Cardiff?

Gabe Electrical carries out electrical inspections and remedial work for homeowners, landlords and businesses throughout Cardiff and the surrounding areas. You can speak directly with the electrician carrying out the inspection and receive a clear explanation of any observations recorded.

For advice or a quotation, visit our EICR and electrical testing service page or contact Gabe Electrical.

Authoritative guidance

The classification descriptions and 2026 FI update in this guide are based on current guidance from NICEIC, the NICEIC Amendment 4 summary and the IET’s explanation of the Amendment 4 changes to FI. Classification always depends on the installation observed and the competent inspector’s professional judgement.