EICR Fault Codes Explained: C1, C2, C3, FI

What Is an EICR?

An Electrical Installation Condition Report (EICR) is the formal document produced after a periodic inspection of an existing electrical installation. It assesses the condition of the fixed wiring, accessories, and protective devices against the current edition of BS 7671 (IET Wiring Regulations).

Instead of a simple pass or fail, an EICR uses a standardised coding system to classify each observation. Understanding these codes is critical for electricians, landlords, property managers, and facilities teams who need to know what each finding means and what must be done about it.

The Four EICR Fault Codes

BS 7671 recognises four codes: C1, C2, C3, and FI. Every observation on an EICR must be assigned one of these codes. The first three indicate the severity of a confirmed defect. FI indicates that a suspected issue needs more investigation.

C1 — Danger Present

A C1 (Danger Present) code means there is an immediate, undeniable risk of electric shock, thermal burns, or electrical fire. Anyone using the installation could be harmed at any moment — not just under fault conditions, but during normal use.

When a C1 is identified, the inspecting electrician has a duty of care under the Electricity at Work Regulations 1989 to make the installation safe before leaving the premises. This usually means isolating the affected circuit and physically locking it off or removing the fuse, then clearly labelling it as out of service.

Real examples of C1 faults

• Exposed live conductors: Damaged cabling where copper conductors are visible and touchable. Missing blanking plates on a consumer unit that expose the live busbar.
• Overheating and arcing: Melted insulation, scorched socket faces, or visible signs of arcing inside switches and junction boxes.
• Missing main earthing: The main earthing conductor is completely broken or disconnected. In a fault, the metal enclosure of equipment could become live at full mains voltage.
• Dangerously oversized fuse or MCB: A 32A breaker protecting a 1.0 mm² lighting circuit. The cable will overheat and can catch fire before the breaker trips.

EICR outcome with a C1: Unsatisfactory. The circuit(s) affected must be isolated immediately and repaired before normal use can resume.

C2 — Potentially Dangerous

A C2 (Potentially Dangerous) code identifies a condition that could become dangerous under fault conditions or with foreseeable misuse. The risk is not immediate, but it is real and must be addressed urgently.

C2 codes make the EICR Unsatisfactory. While you may be able to continue using the installation in the short term — unlike a C1 where the circuit is isolated — the issues must be rectified as soon as possible. For landlords, a C2 means the property cannot be considered compliant with the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020.

Real examples of C2 faults

• Missing RCD protection on socket circuits: A socket outlet that could reasonably be expected to supply outdoor equipment (e.g. a garden shed or power tool) without residual current device (RCD) protection. BS 7671 requires RCD protection for all socket outlets rated up to 32A.
• Cracked accessories: A socket faceplate with a crack that allows moisture ingress or exposes internal parts, even if conductors are not currently exposed.
• Inadequate supplementary bonding: Missing cross-bonding to metal pipework in a bathroom or kitchen with an existing installation that relies on it for safety.
• Damaged cable sheath: External or buried cable where the outer sheath is split or degraded, leaving the inner insulation vulnerable to moisture and mechanical damage.
• Sockets positioned unsafely: A socket outlet installed too close to a water source, such as directly above a sink without proper splash protection.

EICR outcome with a C2: Unsatisfactory. Urgent remedial action required. The installation can be used with caution until repairs are completed, unless the inspecting electrician advises otherwise.

C3 — Improvement Recommended

A C3 (Improvement Recommended) code indicates that an observation does not comply with the current edition of BS 7671, but is not considered dangerous. These are advisory findings where the installation met the Wiring Regulations in force at the time of its original installation but falls short of the latest standards.

If your EICR contains only C3 codes (and no C1, C2, or FI codes), the overall report is Satisfactory. Landlords are not legally compelled to fix C3 items, but addressing them reduces long-term risk and shows proactive safety management.

Real examples of C3 faults

• Old cable colours: Red and black sheathing instead of the modern brown and blue harmonised colours. The installation is still safe, but it does not meet the current colour-coding standard.
• Missing circuit chart: No labelling inside the consumer unit or distribution board identifying which circuit each MCB or fuse protects.
• Absence of RCD protection on buried cables: Cables concealed in a wall at a depth of less than 50 mm without RCD protection — but in a location where mechanical damage is very unlikely.
• Minor cosmetic damage: A small chip in a plastic faceplate that does not expose internal parts or reduce the ingress protection rating.
• Older consumer unit type: A rewireable fuse box or an all-rewireable-fuse consumer unit that, while still functional, does not meet current fire safety recommendations.

EICR outcome with only C3 codes: Satisfactory. No urgent action required, but the recommendations should be considered during future refurbishment or upgrade work.

FI — Further Investigation

An FI (Further Investigation) code is different from C1–C3. It does not confirm a specific defect. Instead, it records that the inspector found evidence of a possible underlying issue that could not be fully assessed during the inspection.

An EICR is a sample-based visual and testing inspection. The inspector cannot open every joint, lift every floorboard, or trace every buried cable. When the inspector sees signs that something may be wrong — but cannot reach, test, or confirm the scope of the problem — they mark it FI.

An FI code makes the EICR Unsatisfactory, just like C1 and C2. The property owner must arrange further investigation (often involving destructive access or more detailed testing) to determine whether a C1, C2, or C3 defect exists behind the inaccessible area.

Real examples of FI findings

• Inaccessible junction boxes: A junction box that has been buried under plaster or floorboards. The inspector cannot verify that the connections inside are sound.
• Suspected borrowed neutral: A lighting circuit where testing suggests a neutral conductor is shared between two different circuits, but the inspector cannot trace the wiring route without lifting floors.
• Partial wiring evidence: A socket that tests correctly but is fed from an unknown source — possibly an older spur or sub-main that was never documented.
• Incomplete bonding verification: The inspector suspects supplementary bonding in a bathroom may be incomplete but a tiled wall prevents full inspection.
• Sample-restricted findings: In a large commercial installation where only a representative sample of circuits was tested, an FI may mark a circuit type that needs 100% inspection before it can be cleared.

EICR outcome with an FI: Unsatisfactory until further investigation is completed and the hidden area is proven safe.

How Codes Affect the Overall EICR Outcome

The presence of one or more codes determines the final verdict:

Printable EICR Fault Code Cheat Sheet

Print this cheat sheet and keep it with your inspection kit. It covers the four codes, their definitions, typical examples, and what each means for the EICR outcome.

EICR Frequency Requirements

How often an EICR is needed depends on the type of property and its use. The table below shows typical intervals based on current regulations and industry guidance:

Who Can Issue an EICR?

An EICR must be carried out by a competent person. In practice, this means a qualified electrician registered with a recognised scheme provider such as the NICEIC, NAPIT, STROMA, or ELECSA. The inspector must hold a current BS 7671 qualification (18th Edition or later) and have the testing equipment to perform the required inspections and measurements.

What Happens After an Unsatisfactory EICR?

If your EICR comes back Unsatisfactory (C1, C2, or FI present):

1. Immediate danger (C1): The inspecting electrician isolates the affected circuit and records the action taken on the report.
2. Urgent repairs (C2): You have a duty to arrange remedial work as soon as possible. For rented properties, the landlord must act within 28 days (or sooner if the inspector specifies).
3. Further investigation (FI): You must instruct the electrician to investigate and resolve the FI items. This may involve lifting floorboards, opening walls, or additional testing.
4. Re-inspection: Once remedial work is complete, a re-inspection or partial re-test is carried out, and the previously identified faults are cleared.

The final EICR document, showing all codes and the remedial actions taken, must be retained. For landlords, this is part of the required documentation under the Electrical Safety Standards Regulations.

Common Misunderstandings About EICR Codes

"C3 means the property is unsafe." No. A C3 on its own does not make the EICR Unsatisfactory. Many properties built before 2018 will have C3 observations purely because the regulations have been updated. That does not mean the wiring is dangerous.

"FI is the same as C2." Not quite. A C2 is a concluded finding. FI means the inspector actively cannot reach a conclusion without more access. An FI may become C1, C2, C3, or nothing at all once investigated.

"An EICR is just a paperwork exercise." An EICR involves physical testing — earth fault loop impedance, insulation resistance, polarity, RCD trip times, and visual inspection. It is not a desktop exercise.

Use InspectionReport for Your EICR Documentation

Once you have your EICR results, you need a clear, professional way to document the findings and communicate them to clients, tenants, or regulators. InspectionReport lets you upload your inspection photos, add notes for each finding, and export a formatted PDF report with severity coding — ready for your client file.

Related Resources

• EICR Electrical Installation Condition Report Checklist — A complete checklist template for conducting EICR inspections.
• Electrical Inspection Report (NFPA 70B) — For US-based electrical inspection reporting.
• Free AI Hazard Identifier — Upload a photo and let AI highlight visible safety hazards.

Frequently Asked Questions