EICR Codes C1, C2, C3 & FI Explained: Which Ones Fail (UK)

Quick answer: An EICR uses four classification codes. C1: danger present (immediate risk, make safe now). C2: potentially dangerous (urgent remedial action). C3: improvement recommended (advisory only; the one code that does not cause a fail). FI: further investigation. Any C1 or C2 makes the report unsatisfactory; an FI did too on forms up to Amendment 3, but not on the Amendment 4 forms in use from 15 October 2026; for English rentals, that starts a 28-day clock to complete remedial work under the Electrical Safety Standards Regulations 2020, with penalties up to £30,000.

Update, October 2026: BS 7671:2018+A4:2026 becomes the only current edition on 15 October 2026. On its EICR form the observations are split into two parts: C1 and C2 decide the outcome, while C3 and FI do not, and FI now reads "further investigation is advised" rather than "required without delay". The 2020 Regulations' 28-day rule has not changed, so treat an FI as something to resolve within 28 days whichever form it is on. Separately, from 1 October 2026 anyone carrying out periodic inspection and testing for a certified business needs a Level 3 inspection and testing qualification. Details in Amendment 4 and the Level 3 rule.

Coming for every English landlord: the Renters’ Rights Act’s PRS Database will require this certificate to be registered per property before you can market or let. See what landlords must register.

The four EICR codes, precisely

C1: danger present

A C1 is the report's red card: the inspector has found something that could injure someone now. Classic C1 findings: accessible live parts (broken socket faces, missing blanks in the consumer unit), incorrect polarity, or conductive parts made live by a fault. Good practice, set out in the industry's Best Practice Guide 4, is for the inspector to make the danger safe immediately and tell the duty holder in writing. If your report carries a C1, treat the installation as unsafe until the remedial work is done.

C2: potentially dangerous

A C2 is the most common cause of an unsatisfactory report. Nothing is dangerous at the moment of inspection, but a single fault or misuse could make it so. Typical C2s: no earthing to exposed metalwork, absence of RCD protection where required for sockets or bathroom circuits, badly deteriorated wiring insulation, or signs of thermal damage in the consumer unit. C2s are why "it's all been working fine for years" is not a defence. The point is what happens when something else goes wrong.

C3: improvement recommended (not a fail)

C3 records that a part of the installation does not meet the current edition of BS 7671 but presents no danger. Older but sound installations collect C3s naturally: wiring colours, older consumer unit enclosures, absence of supplementary bonding where modern rules would want it. A report containing only C3 observations is satisfactory. Whether to act on C3s is a judgement call: during other works, upgrading is often cheap; the observations also give you a ready-made improvement plan for the next rewire.

FI: further investigation required

FI means the inspector found something they could not fully assess within the agreed extent of the inspection (for example, an unexpected reading that needs exploratory work). On forms to Amendment 3 and earlier, FI rendered the report unsatisfactory. On Amendment 4 forms, used for reports from 15 October 2026, it sits in Part 2 of the observations with C3 and does not change the outcome; the IET's stated reason is that FI was being misused, and that fault-finding is remedial work, not part of the inspection. For English rentals the 2020 Regulations still require further investigative work the report requires to be done within 28 days, so the practical advice is unchanged: investigate within 28 days, and the result either clears the issue or converts it into a coded defect.

Pass or fail: when is an EICR satisfactory?

The report concludes either satisfactory or unsatisfactory. On Amendment 4 forms (from 15 October 2026) only C1 and C2 observations make it unsatisfactory; on Amendment 3 and earlier forms an FI did as well. There is no numerical score, and the number of C3s is irrelevant to the outcome. An unsatisfactory report is not a prohibition on using the installation. It is a finding that remedial work is required, on a legal clock if you are a landlord.

UK landlord legal duties

In England, the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 require:

• an EICR at least every 5 years (or sooner if the report specifies)
• a copy to existing tenants within 28 days of the inspection, and to new tenants before occupation
• a copy to the local authority within 7 days of a request
• for C1, C2 or FI: remedial work or investigation completed within 28 days (or the shorter period the report states), with written confirmation supplied to tenants and the local authority within 28 days of completion

Local authorities can fine up to £30,000 per breach and arrange remedial work themselves in default. The certificate is also part of the standard lettings compliance file alongside the gas safety certificate and EPC: the set the PRS Database will require you to register per property, and a natural fit for a landlord's property logbook.

The 28-day rule in practice

The clock starts at the date of the inspection, not the date the paperwork reaches you. Chase your electrician for the report immediately. If the report specifies a shorter period for a serious defect, that shorter period is the legal deadline. Keep the completion certificate or minor works certificate from the remedial visit: the written confirmation you must serve on tenants comes from the person who did the work.

Common findings by code

• C1: broken socket or switch plates exposing live parts; missing consumer-unit blanks; live conductors accessible in junction boxes; incorrect polarity.
• C2: no RCD protection to socket circuits or bathrooms; missing or disconnected main protective bonding to gas/water; damaged flexes and deteriorated insulation; DIY additions with unprotected cable runs; signs of overheating at terminations.
• C3: old wiring colours; no RCD on lighting circuits; plastic consumer unit in a non-escape location; absence of supplementary bonding in an older bathroom where disconnection times are otherwise met.

Frequently asked questions

What does a C1 code on an EICR mean?

C1 means danger is present: an immediate risk of injury, such as exposed live conductors. The electrician should make it safe before leaving, and the report is unsatisfactory until the defect is fixed.

What does a C2 code on an EICR mean?

C2 means potentially dangerous: no immediate risk at the moment of inspection, but a fault that could become dangerous, for example a missing earth connection. Urgent remedial action is required and the report is unsatisfactory.

Is a C3 code a fail on an EICR?

No. C3 means improvement recommended: the installation does not meet current wiring regulations but is not dangerous. A report with only C3 observations is still satisfactory. Fixing C3 items is optional.

Does an FI code still fail an EICR?

On an Amendment 4 form, no: only C1 and C2 make the outcome unsatisfactory, and FI means further investigation is advised. On Amendment 3 and earlier forms an FI made the report unsatisfactory. In England the 28-day rule for required further investigation is unchanged, so resolve an FI within 28 days either way.

How long do landlords have to fix EICR faults?

In England, remedial work for C1, C2 and FI codes must be completed within 28 days, or sooner if the report specifies. The landlord must then obtain written confirmation and supply it to the tenant and, if requested, the local authority within 28 days of completion.

Related guides

• EICR changes October 2026: Amendment 4 and the Level 3 inspector rule
• Consumer unit replacement: certificates and building regs
• The PRS Database: what landlords must register
• Property logbook for landlords
• Scottish landlord records (EICRs are 5-yearly there too)

Reviewed by Jamie Dawson, Editor of Logbook.co.uk, the independent home of the UK logbook. Logbook.co.uk is not a logbook provider and has no commercial relationship with any provider. Corrections: corrections@logbook.co.uk