An Electrical Installation Condition Report (EICR) can run to many pages of test results, but most people who receive one go straight to two things: the overall outcome, satisfactory or unsatisfactory, and the list of observations with their codes. Those codes, C1, C2, C3 and FI, determine what you must do next, how quickly and, for landlords, what the law requires.
The codes are also changing in an important way. BS 7671:2018+A4:2026 (Amendment 4 to the IET Wiring Regulations) changes how FI affects the overall outcome, and from 15 October 2026 EICRs must be carried out to Amendment 4. This guide explains what each code means, how inspectors decide which to use, how the FI change affects you and the practical steps to take once your report arrives.
Key takeaways
- C1 means danger is present; C2 means potentially dangerous. Either makes the report unsatisfactory.
- C3 means improvement recommended and does not make the report unsatisfactory on its own.
- Under Amendment 4, FI (further investigation advised) no longer makes the report unsatisfactory, whereas under Amendment 3 it did.
- Private landlords in England must complete remedial or investigative work required by the report within 28 days, or sooner if the report says so.
- Coding is a risk-based professional judgement. Each code should be justified by reference to a requirement of BS 7671.
What an EICR is actually telling you
An EICR records the condition of an existing electrical installation at the time of inspection. It is produced by a competent person using the model forms in Appendix 6 of BS 7671, and it answers one central question: is the installation safe for continued use?
It is important to understand what the report is not. It is not a check that the installation meets the current edition of the Wiring Regulations in every respect. Most buildings were wired to earlier editions, and an installation can be perfectly safe even though it would not be installed the same way today. The coding system exists to separate genuine safety issues from differences that simply reflect when the installation was built.
For more on how EICRs are planned and priced for commercial buildings, see our complete guide to EICRs for commercial properties.
The four codes at a glance
| Code | Meaning | Effect on outcome | Typical response |
|---|---|---|---|
| C1 | Danger present. Risk of injury. Immediate remedial action required. | Unsatisfactory | Made safe before the inspector leaves, then permanently repaired |
| C2 | Potentially dangerous. Urgent remedial action required. | Unsatisfactory | Repair as a matter of urgency |
| C3 | Improvement recommended. | Does not affect outcome | Consider, prioritise and plan |
| FI | Further investigation advised (Amendment 4 wording). | Does not affect outcome under A4; unsatisfactory under A3 | Arrange the investigation and act on what it finds |
C1: danger present
A C1 is the most serious code. It means there is a risk of injury now: a single event, such as someone touching an accessible part, could cause electric shock or fire. Typical examples include exposed live conductors, a damaged accessory with live parts accessible, or missing covers on a distribution board that expose live parts to people who could reach them.
When an inspector finds a C1, they should not simply write it down and leave. They should tell the person responsible immediately and, with that person’s agreement, make the situation safe, for example by isolating the affected circuit or fitting a temporary barrier. Many contractors also issue a separate dangerous condition notice to record the risk and the action taken.
Warning: If you decline to allow a C1 defect to be isolated or made safe, the risk and the responsibility remain with you. Make sure a permanent repair is arranged quickly and that nobody uses the affected equipment in the meantime.
C2: potentially dangerous
A C2 means the defect is not immediately dangerous, but it would become dangerous if something else happened, such as a second fault or a foreseeable action by a user. Put simply, a C1 needs one event to cause harm; a C2 needs a series of events.
Common examples include the absence of main protective bonding to incoming services, earth fault loop impedance values too high for the protective device to disconnect in the required time, and the lack of RCD protection for socket-outlets that could reasonably be expected to supply portable equipment used outdoors. A C2 should be treated as urgent: it is the code that most often turns a report unsatisfactory, and it represents a real safety gap even if nothing has happened yet.
C3: improvement recommended
A C3 records something that does not meet the current edition of BS 7671 but presents little or no potential for danger in its current circumstances. Older installations commonly attract C3s for things like general-purpose socket-outlets without RCD protection, where they were installed to an earlier edition that did not require it and there is no outdoor use, or incomplete circuit identification at a distribution board.
A report with only C3 observations can still be satisfactory. The government’s guidance for rented homes confirms that landlords are not obliged to carry out C3 improvements, although doing so would improve safety. For commercial duty holders, C3s are a useful input into longer-term planning. Grouping them into a programme of upgrades, for example alongside a distribution board replacement or refurbishment, is usually more efficient than addressing them one by one.
FI: further investigation, and the Amendment 4 change
FI is used when the inspector has seen something that suggests a problem, but the extent or limitations of the inspection mean they cannot identify the cause or confirm whether it is dangerous. An example might be test results that indicate an issue on a circuit whose wiring cannot be fully accessed during the agreed inspection.
What changes under Amendment 4
BS 7671:2018+A4:2026 was published on 15 April 2026, and Amendment 3 is withdrawn on 15 October 2026. NICEIC’s summary of Amendment 4 highlights several changes to the EICR:
- observations are split into two parts, with C1 and C2 in one and C3 and FI in the other;
- only C1 and C2 observations make the report unsatisfactory;
- the FI wording changes from further investigation “required without delay” to further investigation “advised”.
Under Amendment 3 and earlier, an FI made the overall outcome unsatisfactory. Under Amendment 4 it does not. During the transition period, the meaning of an FI therefore depends on which edition the report was produced to, so check the edition reference on the report.
FI is not a substitute for proper inspection
The IET’s Wiring Matters article on further investigation stresses that FI is not a fault-finding exercise and should not be necessary in most circumstances. It gives examples where FI is the wrong choice: an unidentified circuit is a non-compliance in its own right and should be given a classification code, and an insulation resistance below 1 MΩ should be classified rather than investigated further, because tracing its cause is fault-finding.
Tip: If a report contains several FIs, ask the contractor why the matters could not be resolved during the inspection. Good planning, including agreed access, isolations and time on site, should keep FIs to a minimum.
Amendment 4 introduces a range of other changes too. Our article on BS 7671 amendments gives the wider picture.
How inspectors decide which code to use
Coding is a professional judgement, not a lookup table. The same defect can justify different codes depending on the environment and who uses the installation. An exposed live part in a home or a public area is likely to be a C1, while a similar defect in a locked switch room accessible only to skilled persons may be coded differently. The Electrical Contractors’ Association’s guidance on EICR coding sets out a simple decision process: is there an immediate danger (C1)? If not, could a fault or foreseeable event make it dangerous (C2)? If not, it is a C3 at most.
Several principles help keep coding consistent:
- every coded observation should be linked to a requirement of BS 7671, not to personal preference;
- defects against other standards, such as emergency lighting under BS 5266, should be reported separately rather than coded on the EICR;
- over-coding causes unnecessary cost and disruption, while under-coding leaves real risks unaddressed, and neither should be influenced by client pressure;
- industry guidance, including Electrical Safety First’s Best Practice Guide 4, gives examples of typical codes for common situations in dwellings, which many inspectors use as a reference point.
What landlords and duty holders must do
Private and social landlords in England
The Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 require landlords to have the installation inspected and tested at least every five years. Where the report shows that remedial work or further investigation is required, the landlord must have it carried out by a qualified person within 28 days, or within any shorter period the report specifies. They must then give written confirmation of the completed work, together with the report, to the tenant and to the local authority within 28 days of completion. The requirements have been extended to social housing, with a phased introduction during 2025 and 2026, as set out in the government guidance linked above.
Commercial premises and other duty holders
Outside rented housing there is no fixed statutory deadline, but the Electricity at Work Regulations 1989 require systems to be maintained so as to prevent danger, so far as is reasonably practicable. In practice, C1s need immediate action, C2s should be resolved urgently and FIs should be investigated promptly. Insurers, landlords and auditors will often ask for evidence that this has happened.
Closing out the report
Once remedial work is complete, keep the original EICR alongside the certificates for the work, such as an Electrical Installation Certificate or a Minor Electrical Installation Works Certificate. Together they show that the defects identified have been dealt with.
Checking and challenging an EICR
Most reports are accurate and fair, but it is reasonable to question one that seems unclear. Use this checklist when reviewing a report:
- Check the edition of BS 7671 the report was produced to, especially for any FI codes.
- Confirm the extent and limitations section reflects what was agreed, and note anything not inspected.
- Make sure every observation states its location and the circuit or equipment affected.
- Ask for the BS 7671 regulation each C1 and C2 relates to, if it is not obvious.
- Check that the recommended date for the next inspection is reasonable for the type of premises.
- Obtain itemised quotations for remedial work so you can see which costs relate to which code.
- If in doubt, ask for a second opinion from another registered contractor before committing to major work.
How JKS London can help
JKS London is an NICEIC approved contractor, carrying out periodic inspection and testing to BS 7671 for commercial, public sector, retirement living and residential clients since 2004. Our reports are clear about what was inspected, what we found and why each observation was coded as it was, and we can quote for and complete any remedial work, issuing the right certification when it is done.
Find out more about our electrical compliance services, get an instant estimate with our EICR cost calculator, book a commercial EICR online, or contact us to talk through a report you have already received.
Frequently asked questions
Does a C3 mean my EICR has failed?
No. A C3 means improvement is recommended. It does not on its own make the report unsatisfactory, and there is no legal requirement under the private rented sector regulations to carry out C3 improvements, although doing so may improve safety.
Can the electrician who found the defects also fix them?
Yes, and it is often efficient because they already understand the installation. You are free to use any competent contractor for remedial work, and you should receive appropriate certification for the work carried out.
What happens to my EICR after remedial work is done?
The original report stays on file. The contractor issues a certificate for the remedial work, such as an Electrical Installation Certificate or Minor Electrical Installation Works Certificate, which together with the EICR shows the installation is now satisfactory. Private landlords must also provide written confirmation of the completed work.
Why did a different electrician code the same defect differently?
Coding is a matter of professional judgement based on the circumstances, so some variation is normal. Codes should, however, be justified against a requirement of BS 7671, and industry guidance exists to promote consistency. If two reports differ significantly, ask each inspector to explain their reasoning.
Is an EICR a legal requirement for commercial premises?
There is no specific statute requiring an EICR for commercial premises, but the Electricity at Work Regulations 1989 require electrical systems to be maintained to prevent danger. Periodic inspection and testing is the recognised way of demonstrating that, and insurers and landlords commonly require it.
Written by the JKS London technical team. NICEIC-approved engineers and compliance specialists maintaining airports, retirement villages, commercial and public-sector buildings since 2004. This guide is general information — for advice on your premises book a free site visit.
