EICR Codes C1, C2, C3 and FI: What They Mean and How Fast to Act

An Electrical Installation Condition Report (EICR) is the report written after an existing electrical installation is inspected and tested, and it gives each problem it finds a code. The code decides two things: whether the report is satisfactory, and how quickly the work needs doing.

One of those codes, FI, changed this year: Amendment 4 to the wiring regulations, which every new EICR must now follow, changed what an FI does to a report. This guide covers what each code means, what changed, and the deadlines landlords in England work to. It is not a substitute for the standard, an inspector's judgement or legal advice.

Which version applies

The current version is BS 7671:2018+A4:2026. It is Amendment 4 to the 18th Edition, not a new edition. The IET and BSI published it on 15 April 2026, when it could first be used. The previous version, BS 7671:2018+A2:2022+A3:2024, was withdrawn on 15 October 2026, after which Amendment 4 must be used. The IET publishes model forms for Amendment 4, including the EICR.

When you read a report, check which version it was written to, because FI means something different either side of Amendment 4.

C1: danger present

C1 is the most serious code: danger is present, and it needs dealing with straight away.

C2: potentially dangerous

A C2 means an item is potentially dangerous. It needs urgent remedial action.

Like a C1, a C2 means the overall condition must be reported as unsatisfactory, on reports written to Amendment 3 and to Amendment 4.

C3: improvement recommended

A C3 means improvement is recommended. On an Amendment 4 report it is advisory and does not affect the overall assessment, so a C3 never makes the report unsatisfactory, though the IET says it should still be given due consideration.

FI: further investigation

FI is the code whose effect Amendment 4 changed.

• On reports to Amendment 2 or 3, FI read "Further investigation required without delay". The item was recorded in the observations, and the installation was marked unsatisfactory.
• On reports to Amendment 4, FI reads "Further investigation is advised". C3 and FI are now advisory codes, listed apart from C1 and C2. Neither affects the overall assessment, so an FI no longer makes an EICR unsatisfactory.

FI is only for a potential safety issue that could not be fully determined because of the extent or limitations of the inspection. The IET says it should not be necessary to use FI in the majority of circumstances, and that it is often misused. It gives two examples that should be coded, not marked FI: an unidentified circuit, and an insulation resistance reading below 1 MΩ.

How fast to act

• C1: immediately.
• C2: urgently.
• C3: consider it.
• FI: investigate. If you are a landlord in England, see the next section.

The 28-day rule for landlords in England

Landlords in England must have the fixed electrical installation inspected and tested at least every 5 years, or sooner if the last report sets an earlier date, and get a report that gives the results and the date of the next inspection.

If the report shows that further investigative or remedial work is needed, the landlord must have it carried out by a qualified person within 28 days, starting with the date of the inspection, or within any shorter period the report specifies. A C1 or C2 calls for remedial action, so treat it as falling under this rule. The regulations were amended from November 2025, so check the current text for what a landlord can rely on if the work genuinely cannot be done in time.

The duty applies where the report requires further investigative work, and Amendment 4 now calls FI advisory, so as of October 2026 it is not clear whether an FI on an Amendment 4 report still starts the 28-day clock. Until the government says, the safe course is to investigate an FI within 28 days, and a landlord unsure of their position should take advice.

Social housing

The rules now cover social landlords too. SI 2025/1043, in force from 1 November 2025, extended the regulations to social housing and renamed them the Electrical Safety Standards in the Private Rented Sector and Social Rented Sector (England) Regulations 2020. They apply to social tenancies granted on or after 1 December 2025. For older social tenancies they apply from 1 May 2026, and the first inspection and test must take place before 1 November 2026.

Social landlords must also have the electrical equipment they provide under a tenancy inspected and tested at least every 5 years (in-service inspection and testing, often called PAT testing). Private landlords in England have no equivalent duty under these regulations.

Recording codes in Field Forge

Field Forge's compliance forms and inspections include an EICR template, one of 18 UK templates that install in one click:

• Each observation records its code (C1, C2, C3 or FI), the location or circuit, and whether the item is acceptable for continued use. Engineers fill it in on the phone, and it comes to the office for approval before the customer is sent the report. The template's FI option and its help text still use the older wording, "Further investigation required", so change both to "Further investigation is advised" before you use it.
• When the office approves the report, Field Forge offers to raise its failed items as corrective actions, with an owner, a due date and reminders. Pick the EICR code and Field Forge sets a deadline that cannot be moved later: the next day for a C1, and 28 days for a C2 or an FI, counted from when you raise the action.
• The legal 28 days start with the inspection day itself, so even an action raised that day gets a Field Forge deadline one day after the legal last day. Approve the report and raise its actions on the day of the inspection, treat the day before the date shown as the last day, and if the report sets a shorter period, set the action's due date to match it.

Sources

• Mythbuster 13: the four amendments to the rumour mill, IET Wiring Matters, April 2026
• Further investigation, IET Wiring Matters, July 2026
• BS 7671:2018+A4:2026 model Electrical Installation Condition Report, IET
• The Electrical Safety Standards in the Private Rented Sector and Social Rented Sector (England) Regulations 2020, regulation 3, legislation.gov.uk
• SI 2025/1043, which extended the regulations to social housing, legislation.gov.uk, and its explanatory memorandum