EICR Codes Explained: C1, C2, C3 and FI (Real Examples)

Quick answer

An EICR uses four classification codes. C1 means danger is present right now and someone could be injured — the inspector should make it safe before leaving. C2 means potentially dangerous and needs urgent remedial work. FI means something needs further investigation without delay. Any C1, C2 or FI makes the report Unsatisfactory, and in England a landlord must complete the remedial work within 28 days (or sooner if the report says so) under the 2020 Regulations. C3 is only a recommendation — a report with nothing worse than C3s is still Satisfactory and there is no legal obligation to act on it.

I've been inspecting and testing installations for 18 years, mostly in food factories where a duff EICR gets picked apart by auditors, insurers and the client's own engineers. This page is written for both sides of the report: the landlord or homeowner who's just been handed one and wants to know what they actually have to do, and the newly qualified spark trying to code observations without getting shouted at. Same information, honestly presented, for both.

The four codes at a glance

Code	Wording on the report	What it really means	Report outcome
C1	Danger present. Risk of injury. Immediate remedial action required	Someone could be hurt today. Made safe on the spot	Unsatisfactory
C2	Potentially dangerous. Urgent remedial action required	One fault away from danger. Fix it promptly	Unsatisfactory
C3	Improvement recommended	Not to current standards, but not dangerous	Satisfactory (if nothing worse)
FI	Further investigation required without delay	Inspector found something they couldn't fully diagnose	Unsatisfactory

There is no "C4", and there hasn't been since the old Periodic Inspection Report was replaced by the EICR in 2012. If you're looking at a document with codes 1 to 4 on it, it's ancient — get a current EICR done.

C1: danger present

A C1 is the inspector saying "somebody could touch something live, or this could start a fire, before I've even driven off". The expectation — and it's in the industry guidance, not just my opinion — is that the inspector makes the danger safe there and then with the client's permission, or at minimum isolates it and issues a written danger notification before leaving site.

Real examples of C1 from my own reports:

• Exposed live parts. A cracked socket front with the line terminal visible, a missing blank in a consumer unit leaving busbar accessible, a pendant hanging off with bare conductors at head height.
• Incorrect polarity where an accessory or fitting has line and neutral (or worse, line and earth) reversed, leaving exposed metalwork live.
• Live conductive parts. A metal light switch or sink reading 230 V to earth because a fault has energised it and there's no effective earth path to clear it.
• Heat-damaged accessories still in service — a browned, cracked socket that's clearly been cooking, still feeding a tumble dryer.

If your report has a C1 on it, don't negotiate, don't get a second opinion first, don't wait for three quotes. Get it made safe today. Everything else on this page is admin; a C1 is the reason the inspection exists.

C2: potentially dangerous

C2 is the workhorse code and the one most arguments are about. The logic is: the defect isn't dangerous at this exact moment, but a single foreseeable event — a fault, damage, contact during normal use — turns it dangerous. "One fault to danger" is the mental test I give apprentices.

Typical, defensible C2s:

• No RCD protection on socket outlets that can reasonably be expected to supply equipment outdoors — the classic being kitchen or hallway sockets in a house with a garden, where someone will inevitably plug in a mower or hedge trimmer. BS 7671 (Regulation 411.3.3) has required 30 mA RCD protection for general-use sockets since 2008, and the absence of it in a rented dwelling is the single most common reason reports come back Unsatisfactory.
• No RCD protection in a bath or shower room — a location where wet skin and reduced body resistance make a shock far more likely to be fatal.
• Missing circuit protective conductor on a lighting circuit that's had metal switches or Class I fittings added. Common in older houses with two-core lighting cables and somebody's "upgraded" brass switch plates.
• Broken ring final circuit conductor confirmed by end-to-end tests — part of the ring is now an overloaded radial on a 32 A device.
• Borrowed neutrals between circuits — a genuine hazard to the next electrician who isolates one circuit and gets a belt off the neutral of another.
• No main protective bonding to gas or water where extraneous-conductive-parts are present.
• Badly deteriorated rubber-insulated (VIR) wiring that crumbles when disturbed. Depending on condition this can climb to C1.

For landlords: a C2 means the report is Unsatisfactory and the 28-day clock is running (more below). For homeowners: no law compels you, but you're one fault away from the reason the code exists. I'd treat a C2 as this-month work, not someday work.

C3: improvement recommended

C3 means "this doesn't meet the current edition of BS 7671, but it isn't dangerous". This is where a lot of unnecessary panic — and, frankly, a lot of unnecessary selling — happens. A C3 does not fail the report. An installation full of C3s and nothing else is Satisfactory.

Honest C3 examples:

• A plastic consumer unit in good condition. The requirement for non-combustible (in practice, steel) enclosures in dwellings arrived with Amendment 3 and is now Regulation 421.1.201, but existing plastic boards that are undamaged, properly terminated and not showing thermal distress are a C3, not a C2. An inspector coding a healthy plastic board C2 to sell you a board change is coding for their wallet, not your safety.
• No RCD protection on lighting circuits. Required on new work under the 18th Edition; on an existing install it's an improvement recommendation.
• Old wiring colours (red/black). Strictly, old colours on their own aren't even a defect — installations wired before harmonisation are still perfectly compliant with the edition they were built to, and colour tells you nothing about condition. Where both old and new colours exist in the same installation, the missing warning notice at the board is the C3, not the cable colours. Any inspector coding "old colours" as C2 needs to show you which regulation they think is being breached, because there isn't one.
• No supplementary bonding in a bathroom where the circuits are RCD-protected and main bonding is in place — the current regs allow omission in that case, so at most this is a note, and where conditions aren't fully met it's typically C3.
• Missing circuit chart or labelling at the distribution board.

FI: further investigation required

FI is the honest code. It means the inspector found evidence of a problem but couldn't diagnose it within the agreed extent and limitations of the inspection. Examples: ring circuit readings that don't add up and need the ring broken down to trace; an RCD that won't reset with everything disconnected; signs of an undocumented alteration disappearing into a boxed-in ceiling; a Zs reading wildly higher than expected with no obvious cause (see our guide to maximum Zs values for why that matters).

An FI makes the report Unsatisfactory, and rightly so — "I don't know what's going on in that circuit" is not a safe end state. For landlords in England, further investigation is explicitly caught by the 2020 Regulations on the same 28-day footing as remedial work. Budget for the investigation and be aware it may then generate its own C1/C2 findings.

What landlords are legally required to do

For privately rented homes in England, the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 apply. In plain terms:

Obligation	Timeframe
Have a valid EICR by a qualified and competent person	At least every 5 years (or sooner if the report specifies)
Give a copy to existing tenants	Within 28 days of the inspection
Give a copy to new tenants	Before they occupy
Give a copy to the local authority	Within 7 days of a written request
Complete remedial work / further investigation for C1, C2 or FI	Within 28 days, or any shorter period stated on the report
Obtain written confirmation the work is done, and supply it to tenants and the local authority	Within 28 days of completing the work

Local authorities can serve remedial notices, arrange the work themselves and recover costs, and impose financial penalties of up to £30,000 per breach. That last figure concentrates minds: a C2 that would cost half a day's labour to fix is not the thing to gamble a five-figure penalty on.

Two points landlords regularly get wrong. First, C3s carry no legal obligation — you can hand a Satisfactory report with a page of C3s straight to your agent and you're done, though knocking off cheap C3s during other work is rarely a bad investment. Second, the written confirmation of remedial work matters as much as the work itself: get the electrician's certificate or signed confirmation and file it with the EICR, because that paper trail is what you'll produce if the council or your insurer ever asks.

Scotland has required 5-yearly EICRs in private rented housing since 2015, and Wales brought in an equivalent requirement under the Renting Homes (Wales) Act 2022. The coding system is identical UK-wide because it comes from BS 7671, not housing law.

The common coding arguments (and where I land)

Every electricians' forum has a weekly punch-up about coding. The recurring ones:

• Plastic consumer unit: C3. Damaged, scorched or poorly terminated: C2 territory on those findings, not the plastic itself.
• No RCD on sockets: C2 in any dwelling where outdoor use of plugged-in equipment is plausible — which in a rental with any outside space is essentially always. A genuinely enclosed flat with no outdoor access is where reasonable inspectors sometimes argue C3. Code it C2 in rentals and you'll never struggle to defend it.
• No RCD on lighting: C3. Coding it C2 on an ordinary domestic install is over-coding.
• Old colours: not a defect. Missing dual-colour notice: C3.
• Undersized main bonding (e.g. old 6 mm² where 10 mm² is now standard): usually C3 if it's present, connected and sound. Absent altogether with extraneous parts present: C2.
• "Coding to fail": it exists. Some firms use cheap EICRs as a sales funnel for board changes and rewires. If a report is a wall of C2s with no regulation references and a quote stapled to it, pay a genuinely independent inspector for a second opinion before spending thousands.

For new electricians: how to code with confidence

The classification codes come from the model forms in BS 7671, but the book deliberately doesn't tell you how to code individual defects — that's engineering judgement, and judgement needs calibrating. Three things fixed my coding early on:

1. Work from published guidance, not forum folklore. Electrical Safety First's Best Practice Guide 4 is the free industry reference for EICR coding, and the NAPIT EICR Codebreakers book is the best few quid you'll spend as a new inspector — hundreds of photographed defects with an agreed code and reasoning for each. When a landlord challenges your C2, "here's the industry guidance" ends the argument in a way "because I said so" never will.
2. Know the inspection process cold. IET Guidance Note 3 covers inspection and testing methodology, sampling, and extent and limitations — which is where most defensibility problems actually start. A code you can't tie to an observation, and an observation you can't tie to what you actually inspected, is worthless.
3. Trust your instruments, then record everything. A calibrated multifunction tester — I run a Megger MFT1741+ and we've compared the current field in our multifunction tester guide — plus a photo of every C1 and C2 on your phone. One code per observation, a regulation reference where one exists, and never the cowardly "C2/C3". Pick one and stand behind it.

And code as if the installation's next user knows nothing. That tenant will use the garden socket for the strimmer. Their kid will pull the cracked faceplate. If the realistic worst case injures someone, it's not a C3.

For landlords who want a basic sanity check between inspections: a plug-in tester with an RCD test button such as the Martindale EZ650 will flag missing earths, reversed polarity and a non-tripping RCD in seconds. It is in no way a substitute for an EICR — it can't see inside a single joint or junction box — but it catches the obvious stuff before your tenant does.

FAQ

Is a C3 a fail? No. C3 is "improvement recommended". A report containing only C3 observations is Satisfactory, and for landlords there is no legal requirement to act on C3s — though cheap ones are often worth doing anyway.

How long do I have to fix a C2? In an English rental, 28 days from the inspection, or a shorter period if the inspector has specified one on the report — then written confirmation of the work to tenants and (if they asked for the report) the local authority within 28 days of completion. For your own home there's no statutory deadline, but treat a C2 as urgent: the code literally means "potentially dangerous".

Does an Unsatisfactory EICR mean the property needs a rewire? Almost never. Most Unsatisfactory reports are resolved with targeted remedial work — adding RCD protection, replacing damaged accessories, correcting a specific circuit fault. Be suspicious of anyone who jumps straight from a handful of C2s to "full rewire".

Can an inspector give a code for something that was compliant when it was installed? Yes, and it confuses everyone. An EICR assesses the installation against the current edition of BS 7671, so older work can attract codes even though it was fine when fitted. The safeguard is that non-compliance with the current regs is not automatically dangerous — that's exactly the distinction between C3 and C2, and it's where inspector judgement earns its fee.

Who can carry out an EICR? The English regulations require a "qualified and competent person". In practice that means an electrician with inspection and testing qualifications, current calibrated instruments and, usually, membership of a scheme such as NICEIC or NAPIT — ask for evidence of all three, because the competence of the inspector is the difference between the best answer on the internet and a wall of copy-pasted C2s.