EICR codes explained: what C1, C2, C3 and FI actually mean

Published 12 March 2026 · updated 11 June 2026 · SparkCerts guides for UK electricians

Every electrical installation condition report ends in a string of codes, and those codes decide whether the report is satisfactory, what the landlord has to pay for, and what you as the inspector are putting your signature against. The wording in BS 7671 is precise, so it is worth being precise about what each one means.

The four EICR codes

C1: danger present

C1 is the code you hope you never have to write. Exposed live parts at accessible height, a damaged accessory with live conductors touchable, conductive parts that have become live. The duty under a C1 goes beyond the paperwork: you make the danger safe before leaving site, even if that means isolating the circuit and telling the customer it stays off. Note the action you took on the report.

C2: potentially dangerous

C2 covers the faults where nobody is being hurt at this minute, yet one foreseeable event would change that. The classics: no earth at a Class I light fitting, a shower circuit without RCD protection where the regs and risk demand it, undersized tails, signs of thermal damage at a consumer unit. C2 makes the whole report unsatisfactory, and on a rental property that starts a legal clock.

C3: improvement recommended

C3 is for installations that were compliant when installed and have simply been overtaken by the regs. Older wiring colours, a consumer unit in combustible material that predates Amendment 3, no RCD on a socket circuit that a risk assessment can live with. A report full of C3s can still be satisfactory. Resist the temptation to inflate a C3 to a C2 to force work; assessors read reports, and so do other electricians.

FI: further investigation

FI is the honest code for the things an inspection could not get to the bottom of within the agreed extent and limitations: an unexpected reading you could not chase down, an inaccessible junction box you have reason to distrust. FI makes the report unsatisfactory until someone investigates, so use it when it is genuinely warranted rather than as a hedge.

What landlords have to do about each code

Under the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020, a rental property needs an EICR at least every five years. If the report contains C1, C2 or FI, the landlord must complete the remedial or investigative work within 28 days, or sooner if the report says so, and supply written confirmation to the tenant and, if asked, the local authority. C3 items carry no legal obligation.

How common faults are usually coded

Context always decides the final code, but most inspectors land in the same place on the everyday observations. This is how the common ones tend to fall on a domestic installation, and it answers most of the "is this a C2 or a C3" questions before they start.

Treat that as a starting point, not a lookup table to hide behind. A C3 plastic board with scorch marks around the main switch is a C2, and a missing bond on a property with a plastic incoming water main may not need bonding at all.

C2 or C3: the call that gets argued

The line between potentially dangerous and improvement recommended is where complaints, scheme assessments and the occasional county court claim live. You are not expected to decide it alone. Electrical Safety First publishes Best Practice Guide 4 on the classification of observations, and NAPIT's Codebreakers does the same job in booklet form. They exist precisely so two competent inspectors reach the same code on the same fault, and naming the guide you followed in your notes is a strong position if the coding is ever challenged.

Two pressures distort coding in opposite directions. One is upcoding a C3 to a C2 to manufacture remedial work, common where the inspection is a loss leader for the repair quote. The other is downcoding a C2 to a C3 to keep a landlord or agent happy and the report satisfactory. Both are the same failure: coding to an outcome rather than to the danger. Assessors read reports, landlords change electricians, and the signature on the report is yours either way.

What an unsatisfactory outcome actually triggers

One C1, C2 or FI makes the overall assessment unsatisfactory, and on a private rental that starts the clock described in our guide to landlord EICR requirements: the remedial work must be completed within 28 days, with written confirmation to the tenant and, on request, the council. A C1 carries an extra duty on the day, because danger is present: make it safe before you leave, even if that means isolating the circuit and noting the action on the report.

Coding consistently is what protects you

The grey areas between C2 and C3 are where complaints and scheme assessments live. Two habits help. First, code against the danger, the regulation number, and what you actually observed, written on the report in plain words. Second, keep your reports somewhere you can find them in five years, because the next inspector, the landlord's agent, or an assessor may ask what you saw and why you coded it that way.

Common questions

Is a C3 a fail on an EICR?

No. C3 means improvement recommended. The installation can still be reported as satisfactory with C3 items on it. Only C1, C2 and FI make a report unsatisfactory.

Does a landlord have to fix a C3?

Not by law. The Electrical Safety Standards regulations require remedial work for C1, C2 and FI within 28 days. C3 is a recommendation, though fixing cheap C3 items is often worth it while the electrician is there.

What is the difference between C1 and C2?

C1 means danger is present right now and people are at risk; it needs immediate action. C2 means the danger is not present at this moment, but a fault sequence could realistically make it dangerous, so it is potentially dangerous and still makes the report unsatisfactory.

Is no RCD a C2 or C3?

Usually C2 where current regulations expect RCD protection and ordinary people use the circuit: socket outlets, cables buried less than 50mm in a wall without mechanical protection, and circuits in a bathroom. It can be C3 on an older installation where a documented assessment supports leaving it, but the common and defensible code for a domestic socket circuit with no RCD is C2.

Is a plastic consumer unit a C2 or C3?

A combustible consumer unit on its own is normally C3. Non-combustible enclosures became the requirement with Amendment 3 in 2016, so a plastic board fitted before that was compliant when installed. It moves to C2 if there is evidence of overheating, loose or arcing connections, or other aggravating factors.

How many C2s make an EICR fail?

One. A single C1, C2 or FI anywhere in the installation makes the overall assessment unsatisfactory. There is no points total and no safe number of C2s.

Can you let a property with a C3 on the EICR?

Yes. C3 is improvement recommended and does not make the report unsatisfactory, so a rental can be let with C3 items outstanding. Only C1, C2 and FI carry the legal duty to remedy within 28 days.