EICR Codes Explained: What C1, C2, C3 and FI Really Mean

You've had your Electrical Installation Condition Report (EICR) done and the result has landed on your desk full of codes — C1, C2, C3, FI — and an overall verdict of "satisfactory" or "unsatisfactory". If that means very little to you, you're not alone. This guide explains exactly what each EICR code means, what makes a report fail, and what remedial work each one calls for.

What an EICR code is

When a qualified electrician inspects a property's fixed wiring against [BS 7671](/electrician-doncaster/) (the 18th Edition Wiring Regulations), every defect they find is recorded as an observation with a classification code. The code tells you how serious the issue is and how urgently it needs dealing with. There are four codes you'll see on a UK EICR:

• **C1** — Danger present
• **C2** — Potentially dangerous
• **C3** — Improvement recommended
• **FI** — Further investigation required

The overall report outcome — satisfactory or unsatisfactory — is decided entirely by which of these codes appear. Understanding them is the difference between panicking over a harmless note and ignoring something genuinely dangerous.

C1 — Danger present

A C1 means there is a risk of injury right now. Someone could be electrocuted or the installation could cause a fire in its current state. This is the most serious code on the report.

Typical C1 findings include exposed live conductors, a socket or accessory with live parts accessible to touch, or incorrect polarity that energises something that should be earthed. When an electrician finds a C1, they should make it safe immediately — often by isolating the affected circuit before they even leave — and the issue must be put right without delay.

A single C1 makes the whole report unsatisfactory. There's no negotiating with a C1: it gets fixed first.

C2 — Potentially dangerous

A C2 means the fault is not an immediate danger today, but it could become dangerous under fault conditions — for example, if something else fails, or if someone touches the wrong thing at the wrong time. C2s are the most common reason a report is marked unsatisfactory.

Common C2 observations include:

• No RCD protection on circuits that need it (sockets, cables buried in walls)
• Inadequate or missing earthing and bonding
• An old re-wireable (rewireable fuse) consumer unit with no protective devices
• Damaged cable insulation or accessories
• Borrowed neutrals between circuits

Like a C1, any C2 makes the report unsatisfactory and requires remedial action. Many C2s are cleared by a [consumer unit upgrade](/consumer-unit-upgrades/) to a modern board with RCBOs (devices that combine overload and earth-fault protection on each circuit), or by correcting earthing and bonding.

C3 — Improvement recommended

A C3 is the one that confuses people most. It means the installation isn't dangerous and isn't a failure — but it doesn't meet the current standard, and bringing it up to date would improve safety. C3 items are recommendations, not requirements.

Examples include the absence of RCD protection on a circuit where it wasn't required when the property was built, or older-style accessories that work perfectly well but predate current guidance. Importantly:

> A report with only C3 codes is still satisfactory.

You don't have to act on C3 items to be compliant, but they're worth considering — especially during a rewire, a board change, or other works when the cost of upgrading is marginal. Many landlords and homeowners choose to clear C3s simply for peace of mind.

FI — Further investigation required

An FI code means the inspector found something that needs deeper investigation before its risk can be classified. It's not a verdict — it's a flag that something couldn't be fully assessed on the day, perhaps because a circuit couldn't be safely tested or a reading was unexpected.

An FI code makes a report unsatisfactory, because the safety of that part of the installation is unknown until it's checked. Resolving an FI usually means a return visit for targeted [electrical fault finding](/electrical-fault-finding/) to trace the issue, after which it's re-coded as C1, C2, C3 or cleared entirely.

What makes a report "unsatisfactory"

Here's the simple rule. A report is marked unsatisfactory if it contains any C1, C2 or FI code. It is satisfactory only if it contains no C1, C2 or FI codes — C3 codes on their own don't fail it.

| Codes present | Outcome | |---|---| | C1 (any) | Unsatisfactory | | C2 (any) | Unsatisfactory | | FI (any) | Unsatisfactory | | C3 only | Satisfactory | | No codes | Satisfactory |

An unsatisfactory result doesn't mean the property is uninhabitable — it means specific things need putting right. For landlords, the remedial work must be completed within 28 days (or sooner if stated), with written confirmation issued afterwards.

What remedial work typically involves

The right fix depends entirely on what was coded. In practice, the most common remedial jobs we carry out after an unsatisfactory EICR in the Doncaster area are:

• **Consumer unit upgrade.** Swapping an old fuse board for a modern RCBO board clears a cluster of C2s in one visit and is often the single most cost-effective fix.
• **Earthing and bonding upgrades.** Adding or correcting main protective bonding to gas and water services, and improving earthing arrangements.
• **Repairing damaged accessories and cabling.** Replacing cracked sockets, scorched fittings or perished insulation.
• **Adding RCD protection.** Bringing circuits in line with current shock-protection requirements.
• **Targeted fault finding.** Tracing and resolving anything flagged FI before re-coding it.

After remedial work, you should receive documentation confirming the work was done and, where appropriate, that affected circuits now comply. Notifiable work falls under Part P of the Building Regulations, so it should be carried out and certified by a registered electrician.

Get your codes explained — and fixed — properly

If you're holding an unsatisfactory EICR and aren't sure what it's telling you, we'll walk you through it line by line, explain which codes genuinely need action, and quote clearly for any remedial work. No scare tactics, no padded job sheets. For a sense of what inspections and follow-up work cost, see our [EICR cost guide](/eicr-cost/).

AMP Pro Electrical is NICEIC and NAPIT registered and based in Armthorpe, DN3, covering Doncaster and the wider South Yorkshire area. Call us on 0333 577 5464 or [get in touch](/contact/) for a free, no-obligation look at your report and a straight answer on what needs doing.