EICR Codes Explained: C1, C2, C3 and FI
What each code means, what action is required, and how the overall outcome is determined. Includes an interactive observation coding tool based on Best Practice Guide 4.
What are EICR codes?
Every observation recorded on an Electrical Installation Condition Report (EICR) is classified using one of four standard codes.
The code tells you — and any future inspector — how serious the observation is, what action is required, and how it affects the overall outcome of the report.
The four codes are C1, C2, C3 and FI. This guide and helper use Electrical Safety First Best Practice Guide 4 Issue 7.4 (August 2026), updated to BS 7671:2018+A4:2026, with outcome guidance from the IET On-Site Guide, Ninth Edition (2026).
An EICR should be a safety report, not a wish list of upgrades. If you are comparing advertised prices, our guide to cheap EICR Leicester explains what can happen after a low-cost inspection.
| Code | Meaning | Report outcome | Action required |
|---|---|---|---|
| C1 | Danger present | Unsatisfactory | Immediate remedial action |
| C2 | Potentially dangerous | Unsatisfactory | Urgent remedial action |
| C3 | Improvement recommended | Does not by itself make the report Unsatisfactory | Improvement recommended |
| FI | Further investigation is advised | Does not by itself make the report Unsatisfactory | Investigate as soon as possible |
Danger Present
Immediate action required — report outcome: Unsatisfactory
A C1 observation means there is an immediate risk of electric shock or fire. The installation or affected circuit must be made safe without delay.
Any EICR containing a C1 observation is automatically classified as Unsatisfactory.
Typical C1 examples
- Live parts directly accessible — exposed conductors, missing consumer unit covers
- Severe overheating or fire damage where live parts are accessible or the installation is unsafe to leave energised
- Exposed-conductive-parts confirmed live
- Incorrect polarity at the origin of the installation
- Damaged accessory or enclosure with live parts directly accessible
Potentially Dangerous
Urgent remedial work required — report outcome: Unsatisfactory
A C2 observation means the defect is not an immediate danger in current conditions but could become dangerous if left unaddressed.
Any EICR containing a C2 observation is classified as Unsatisfactory until the defect is rectified and the installation re-verified.
Typical C2 examples
- Confirmed absence of an effective means of earthing
- RCD or RCBO failing to operate correctly under test
- Socket-outlet other than SELV or a shaver socket-outlet less than 2.5 m horizontally from the boundary of bathroom Zone 1
- Incorrect polarity at a final circuit, equipment or accessory
- Absence of additional protection by RCD for a circuit supplying a socket-outlet in a location containing a bath or shower
- Absence of supplementary bonding where required in a location containing a bath or shower, when the conditions permitting omission are not satisfied
- Absence of main protective bonding to a confirmed extraneous-conductive-part
- Cross-sectional area of the earthing conductor does not satisfy the adiabatic requirements of Regulation 543.1.1
- Confirmed insulation resistance below 1 MΩ between live conductors connected together and Earth, from a valid assessment of the installation
- Earth fault loop impedance too high for the prescribed disconnection time, with no RCD providing the required fault protection
- Damaged accessory with live parts not directly accessible but protection compromised
- Borrowed neutral
- Ring final circuit conductor discontinuity or cross-connection
Improvement Recommended
Not a failure — report can still be Satisfactory
A C3 observation is not a failure. It means the installation does not fully comply with current requirements but is not considered dangerous.
An EICR containing only C3 observations can still be issued as Satisfactory.
C3 is commonly applied to older installations that were installed correctly to the standards of the time but do not meet every current requirement.
Typical C3 examples
- No additional RCD protection for a socket-outlet unlikely to supply mobile equipment outdoors, not serving a bath or shower location, and whose use is not considered potentially dangerous
- Type AC RCD installed where Type A is now required (default BPG4 position)
- Absence of a Surge Protective Device (SPD) where required by Regulation 443.4.1 (a) & (c)
- No RCD additional protection for cables concealed at less than 50 mm depth without an earthed metallic covering, earthed metal enclosure or mechanical protection against penetration
- Absence of additional RCD protection for bathroom circuits other than socket-outlet circuits, where satisfactory supplementary bonding is present
- Main protective bonding connection to gas, water or other installation pipe inaccessible for inspection, testing and maintenance, with adequacy checked by continuity testing
- Combustible consumer unit or similar switchgear, not inside a non-combustible enclosure, under a wooden staircase or within the sole route of escape
- Absence of circuit identification labels
- No CPC in a lighting circuit having only Class II or all-insulated equipment unlikely to be replaced by Class I equipment
- Wiring not adequately supported against collapse in a fire (general circuits)
Further Investigation Is Advised
Investigate as soon as possible — does not by itself make the report Unsatisfactory
FI is used where inspection or testing has identified a potential safety issue, but the inspector cannot determine the appropriate Classification Code without further investigation because of the extent or limitations of the inspection.
Further investigation should be carried out as soon as possible to obtain the information necessary to determine the appropriate classification.
An FI observation on its own does not make an EICR Unsatisfactory. An Unsatisfactory outcome results from the presence of a C1 or C2 observation.
In domestic and similar installations, FI should be relatively uncommon. Best Practice Guide 4 Issue 7.4 gives no standard FI examples for these installations because it should generally be possible to assign C1, C2 or C3, or record an appropriate limitation.
Inaccessibility alone does not justify FI. An inaccessible area may be an agreed or operational limitation; where main protective bonding adequacy can be established by continuity testing, an inaccessible connection is a C3 example.
What is R1+R2 on an EICR?
R1+R2 is a continuity test carried out during EICR testing on each circuit. The result is used to calculate the earth fault loop impedance (Zs) for the circuit. R1+R2 is a test result, not a code.
How EICR outcomes are determined
The overall outcome of an EICR is either Satisfactory or Unsatisfactory. Any C1 and/or C2 observation makes the report Unsatisfactory. C3 only, FI only, or C3 and FI together without C1 or C2 do not lead to an Unsatisfactory outcome; the report may remain Satisfactory. FI still calls for investigation as soon as possible.
Select an observation to explore
This tool covers the most common EICR observations across domestic and light commercial installations. It uses Electrical Safety First Best Practice Guide 4 Issue 7.4 as its primary classification guidance. Not every possible observation is included — where an observation is not listed, or where the tool indicates further assessment is needed, inspector judgement and reference to BS 7671 and BPG4 apply.
EICR Observation Code Helper
Select a category and observation above to see the likely code and suggested wording.
Frequently asked questions
No — and it is important to be clear about this. This tool provides guidance based on Best Practice Guide 4 Issue 7.4. It helps you explore likely coding for common observations, but it does not know the specific details of the installation in front of you, the results of your tests, or the conditions present at the time of inspection. Final classification of every observation always remains the responsibility of the qualified and competent inspector. No tool, checklist or software can substitute for professional judgement, experience, and thorough inspection and testing.
No. The material alone does not make an EICR Unsatisfactory. Best Practice Guide 4 Issue 7.4 gives C3 where a combustible consumer unit or similar switchgear (for example, plastic) is not inside a non-combustible enclosure and is under a wooden staircase or within the sole route of escape. Elsewhere, with no other defect, this is NC only (a non-compliance), not normally recorded as an EICR observation. Damage, overheating, missing blanks and other defects must be assessed separately. See also: PRS 2025 EICR update guide.
Best Practice Guide 4 Issue 7.4 classifies a Type AC RCD installed where Type A is required as C3, and that is the default position used by this tool. Final classification remains the inspector's judgement. A Type AC RCD provides residual current protection but does not detect pulsating DC residual currents. Best Practice Guide 4 Issue 7.4 classifies this departure as C3.
No. Main protective bonding is only required to extraneous-conductive-parts — parts that introduce a potential from outside the installation into the building. Not all metallic services, sinks, baths or pipework qualify as extraneous-conductive-parts. For example, a metallic sink connected only to plastic pipework does not introduce an external potential and is therefore not an extraneous-conductive-part requiring main bonding. Automatically coding the absence of bonding to such parts is incorrect and can mislead clients. Before applying any bonding code, the inspector must confirm the nature of the service or part in question.
Because the risk presented by a defect often depends on the specific circumstances of the installation and the condition of the installation at the time of inspection. This is at the heart of Best Practice Guide 4 Issue 7.4 — the defect is coded, and the code reflects the actual risk presented, not a blanket rule. For example, a damaged outdoor accessory presents an immediate danger (C1) if live parts are directly accessible through the damage, but a significant risk requiring urgent attention (C2) if the enclosure is damaged but live parts remain inaccessible. This is why the tool asks conditional questions for certain observations — the same fault can present very different levels of risk in different scenarios.
Best Practice Guide 4 (BPG4) is a guidance document produced by Electrical Safety First in collaboration with industry bodies including the ECA, NAPIT, NICEIC and others. It provides guidance to help inspectors apply consistent and appropriate coding to EICR observations. BPG4 encourages a defect-based, risk-assessed approach to coding rather than blanket rules based on age or materials. It uses the C1, C2, C3 and FI code system defined by BS 7671 and the model forms. This tool uses Electrical Safety First Best Practice Guide 4 Issue 7.4, updated to BS 7671:2018+A4:2026, as its primary classification-code guidance. BPG4 supports inspection decisions; it is not itself BS 7671. See also: our EICR information hub and landlord EICR information.
Real EICR findings from recent inspections
The photos below are from actual EICR inspections carried out in Leicester and surrounding areas. Each illustrates a type of observation that appears regularly during domestic inspections.
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