EICR Observation Codes Explained
A complete guide to C1, C2, C3, and FI observation codes. Real examples, classification criteria, and how to write clear observations that stand up to scrutiny. For UK electricians.
| Code | Meaning | Action required | EICR outcome |
|---|---|---|---|
| C1 | Danger Present | Immediate | Unsatisfactory |
| C2 | Potentially Dangerous | Urgent | Unsatisfactory |
| C3 | Improvement Recommended | Advisory | Satisfactory |
| FI | Further Investigation | Without delay | Unsatisfactory |
What Are EICR Observation Codes?
Observation codes are the classification system used on an Electrical Installation Condition Report (EICR) to communicate the severity of any defects, departures from the standard, or safety issues found during an inspection. Every time an inspector identifies something that departs from BS 7671 or represents a defect, they record it as an observation and assign one of four classification codes: C1, C2, C3, or FI.
The coding system was introduced to provide a consistent, standardised method for classifying observations across the industry. Before the current system, different inspectors and different scheme providers used different terminology, making it difficult for property owners and other stakeholders to understand the severity of identified issues. The current C1, C2, C3, FI system — as defined in GN3 Table 3.5 (IET Guidance Note 3, 9th edition) and required by Regulation 3.11 of that guidance — provides a common language that is understood across the UK electrical industry. Scheme providers including NAPIT, NICEIC and ELECSA audit completed EICRs against the definitions in Table 3.5.
The observation codes are used during the periodic inspection of existing installations (producing an EICR). They are not used on Electrical Installation Certificates (EICs), which cover new installations. On an EIC, any non-compliance should be rectified before the certificate is issued, so there is no need for classification codes. The EICR, by contrast, reports on the condition of an installation as found, which may include defects of varying severity. Preparing for your C&G 2391-52 inspection and testing qualification gives you the knowledge to code observations consistently and correctly.
Understanding when and how to apply each code is one of the most important skills an inspector can develop. Incorrect coding undermines the credibility of the report, can cause unnecessary alarm to property owners, or — more dangerously — can understate a genuine safety risk. This guide covers each code in detail with real-world examples.
C1 — Danger Present
Risk of injury. Immediate remedial action required.
A C1 code indicates that there is an immediate danger of injury to persons or livestock. This is the most serious classification and requires immediate action. When a C1 observation is identified, the inspector must advise the person responsible for the installation immediately, and the danger should be removed or made safe before the inspector leaves the premises if at all possible.
C1 observations are relatively rare on well-maintained installations, but when they occur, they represent genuine dangers that could cause electric shock, burns, or fire. The inspector should document the danger clearly, advise the responsible person in writing, and record on the report that the responsible person has been informed.
C1 Examples
- Exposed live parts — live conductors accessible to touch, such as a damaged socket outlet with exposed terminals, or a missing blanking plate on a consumer unit revealing live busbars.
- Absent earthing — the main earthing conductor is disconnected or missing entirely, leaving the entire installation without an earth path. Any earth fault would not be cleared by the protective devices.
- Severely damaged distribution board — a consumer unit with fire damage, melted components, or structural failure that exposes live conductors or compromises the enclosure rating.
- Overloaded circuits with visible damage — cables showing signs of overheating (discoloured insulation, burnt smell), combined with undersized protection or missing protection, presenting an immediate fire risk.
- Metalwork at a dangerous potential — extraneous-conductive-parts (such as metal pipework or structural steelwork) found to be live to touch due to a wiring fault or absent bonding.
C2 — Potentially Dangerous
Risk of injury may arise. Urgent remedial action required.
A C2 code indicates that whilst there may not be an immediate danger at the time of the inspection, a risk of injury could arise under certain foreseeable conditions. The defect requires urgent remedial action to prevent it from becoming dangerous. C2 is the most commonly debated classification code because it requires the inspector to make a professional judgement about the likelihood of danger occurring.
The distinction between C2 and C1 is immediacy. A C1 is dangerous right now — someone could be injured at this moment. A C2 is not immediately dangerous but could become so. For example, missing RCD protection on a socket circuit is not immediately dangerous (the circuit may be working fine), but if an earth fault occurs and there is no RCD to clear it quickly, injury could result.
C2 Examples
- Inadequate bonding — main bonding conductors to water and gas services missing, undersized, or not properly connected. Under a fault condition, this could result in a dangerous potential difference between services.
- Missing RCD protection — socket outlet circuits accessible to the public or in locations with increased risk (bathrooms, kitchens, external areas) without 30mA RCD protection as required by the current edition of BS 7671.
- Undersized cables — circuit cables with a current-carrying capacity lower than the rating of the protective device, meaning the cable could overheat before the device operates.
- Lack of discrimination — protective devices configured such that a fault on one circuit causes a higher-level device to operate, disconnecting multiple circuits unnecessarily and potentially affecting safety services.
- Zs exceeding maximum permitted value — the measured earth fault loop impedance for a circuit exceeds the value tabulated in BS 7671 for the protective device, meaning the device may not disconnect within the required time during an earth fault.
C3 — Improvement Recommended
Does not comply with current standard. Not dangerous. Improvement recommended.
A C3 code indicates that a part of the installation does not comply with the current edition of BS 7671 but is not considered dangerous. These are typically features that were acceptable under the regulations in force when the installation was originally carried out, but do not meet the requirements of the current 18th Edition. The inspector recommends improvement but acknowledges that there is no immediate safety risk.
C3 observations do not make the EICR Unsatisfactory. A report with only C3 codes (and no C1, C2, or FI codes) is classified as Satisfactory. This is an important distinction because it means the installation is safe for continued use, even though improvements would bring it closer to the current standard.
C3 is sometimes misunderstood by property owners, who may see "Improvement Recommended" and assume the work must be done. It is the inspector's role to explain that C3 items are advisory, not mandatory, and that the installation remains safe. However, the property owner should be encouraged to consider the improvements, particularly if they plan to carry out other electrical work in the future.
C3 Examples
- No RCD protection on older installations — socket circuits installed before the requirement for RCD protection was introduced. Not required at the time of installation and not considered dangerous, but RCD protection would improve safety.
- Label deficiencies — circuit labels on the distribution board that are faded, incomplete, or do not match the actual circuit arrangement. Not dangerous, but clear labelling is important for safe working.
- Accessibility issues — the consumer unit is located in a position that makes it difficult to access in an emergency, such as behind stored items or at an awkward height. The current regulations require the means of switching off to be readily accessible.
- Older wiring colours — the installation uses red/black wiring colours from the previous standard rather than the current brown/blue harmonised colours. Not dangerous in itself, but re-identification with coloured sleeving would aid safe working.
- Supplementary bonding no longer required — supplementary equipotential bonding in a bathroom that is no longer required under the current regulations (where all circuits are RCD protected and disconnection times are met), but is still in place. C3 recommends no action is needed but notes the observation for the record.
FI — Further Investigation
Further investigation required without delay.
An FI code indicates that the inspector was unable to fully assess a part of the installation during the inspection, and further investigation is needed before a definitive classification can be given. FI is not a classification of severity like C1, C2, or C3 — it is an acknowledgement that more work is required to determine the condition of a specific aspect of the installation.
FI must always be accompanied by a clear explanation of why further investigation is needed and what additional work is required. Simply writing "Further investigation required" without context is poor practice and will likely be challenged by scheme providers or clients. The description should explain what the inspector could not access or test, why they could not do so, and what specific investigation or testing is recommended.
FI is sometimes perceived as a "cop-out" code — a way for inspectors to avoid making a difficult classification decision. This perception is wrong. FI serves a genuine and important purpose: it prevents inspectors from guessing about things they cannot see or verify. Coding something as Satisfactory when you have not actually been able to inspect it is far more dangerous than honestly recording that further investigation is needed.
FI Examples
- Inaccessible wiring — cables concealed in walls, floors, or ceilings that cannot be inspected or tested without invasive work. For example, the inspector suspects that cables routed through a ceiling void may be in contact with thermal insulation but cannot access the void to verify.
- Buried cables of unknown route — cables identified entering or leaving an accessory plate that disappear into a solid wall or floor and their route and condition cannot be determined without opening up the structure.
- Suspected issues behind plasterwork — signs of previous water ingress or discolouration around an electrical accessory suggesting possible damage to concealed wiring, but the extent cannot be determined without removing the plaster.
- Inconsistent test results — test readings that do not match expected values and the cause cannot be determined during the inspection. For example, an unusually high R1+R2 value on a circuit that may indicate a loose connection at a point that cannot be accessed during the current visit.
- Locked or occupied areas — parts of the installation in rooms or areas that were locked or in use during the inspection and could not be accessed. The FI should specify which areas and what testing is required when access is available.
How to Write Good Observation Descriptions
The quality of your observation descriptions directly affects the usefulness of the EICR. A good observation is specific, actionable, and references the relevant regulation. A poor observation is vague, ambiguous, and leaves the reader unsure of what was found or what needs to be done.
Every observation should answer three questions: What was found? Where was it found? Which regulation does it relate to? For example, instead of writing "Bonding inadequate", write "Main protective bonding conductor to incoming water service is absent. Regulation 544.1.2 requires the main protective bonding connection to any extraneous-conductive-part to be made as near as practicable to the point of entry." The second version tells the reader exactly what the problem is, where it is, and which regulation requires it to be addressed.
For FI observations, also explain why further investigation is needed and what specific work is recommended. Instead of "Further investigation required to ceiling void", write "Cables entering ceiling void above first-floor landing could not be inspected as no access hatch is present. Recommend access hatch be installed to permit inspection of cable routing and condition, particularly in relation to thermal insulation contact (Regulation 523.9)."
Poor Observations
- "Bonding inadequate"
- "RCD not working properly"
- "Some circuits need attention"
- "Old wiring"
- "Further investigation required"
Good Observations
- "Main bonding to water service absent. Reg 544.1.2."
- "RCD serving kitchen sockets tripped during test at 22 mA. Rated residual current 30 mA. Replace RCD — device operating below rated tripping threshold."
- "Circuit 7 (first-floor ring) — Zs measured 2.15 ohms, max permitted 1.37 ohms for B32. Reg 411.3.2."
- "Red/black wiring colours present throughout. Not re-identified with sleeving/markers. C3 — Reg 514 (identification of conductors)."
- "Cables in loft void laid directly on thermal insulation. Access limited — FI to determine extent. Reg 523.9."
Overall Assessment: Satisfactory vs Unsatisfactory
The overall assessment on an EICR is a binary judgement: Satisfactory or Unsatisfactory. The rule is straightforward.
Satisfactory
The installation is safe for continued use. No C1, C2, or FI observations are present. There may be C3 observations (improvement recommended), but no items that represent a current or potential danger and no areas requiring further investigation. The person responsible can continue to use the installation with confidence.
Unsatisfactory
One or more C1, C2, or FI observations are present. The installation is either currently dangerous (C1), potentially dangerous (C2), or could not be fully assessed (FI). Remedial action or further investigation is required. The person responsible must arrange for the identified defects to be corrected or investigated by a competent person, and confirmation of completion should be obtained.
An important point often overlooked is the treatment of FI observations in relation to the overall assessment. An FI observation makes the report Unsatisfactory. This is because the inspector could not fully determine the condition of part of the installation, and the installation cannot be confirmed as safe until that investigation is completed. FI observations must be actioned without delay so that the area in question can be properly assessed and the appropriate classification (C1, C2, C3, or no defect) can be determined.
The Landlord's Duty When Observations Are Raised
Under the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020, landlords have specific legal obligations when an EICR raises observations. Understanding these obligations is important for both inspectors (who need to communicate them to landlords) and landlords (who need to act on them).
When the EICR identifies observations requiring urgent action (any C1, C2, or FI code), the landlord must ensure that investigative or remedial work is completed within 28 days of the inspection date, or within any shorter period specified by the inspector on the report. For C1 (Danger Present) observations, inspectors often specify a shorter period — in some cases, immediate action is required before the premises can be safely occupied.
After the remedial work is completed, the landlord must obtain written confirmation from a qualified person that the work has been done to a satisfactory standard. This confirmation must be provided to the local housing authority within 28 days of the remedial work being completed if requested. The landlord must also supply a copy of the report (and any confirmation of remedial work) to the tenants within 28 days.
Failure to comply with these requirements can result in local authority enforcement action, including civil penalties of up to 30,000 pounds per breach, remedial action notices requiring specific work to be carried out, and in extreme cases, the local authority may arrange for the work to be done and recover costs from the landlord. These are significant consequences, and inspectors should ensure landlords understand their obligations when handing over an Unsatisfactory EICR.
Common Mistakes Inspectors Make When Coding Observations
Even experienced inspectors make coding errors. Recognising these common mistakes helps you avoid them and produce more accurate, defensible reports.
Over-coding with C2 when C3 is appropriate
Some inspectors code everything as C2 "to be safe." This makes every report Unsatisfactory and devalues the coding system. If a feature was compliant when installed and does not present a risk, it is C3, not C2. Consider the actual risk, not just the departure from the current standard.
Under-coding with C3 when C2 is warranted
The opposite mistake: coding a genuine safety issue as C3 to avoid making the report Unsatisfactory. This is dangerous and can expose the inspector to liability. If there is a real risk of injury, it must be coded C2 (or C1) regardless of the consequences for the overall assessment.
Using FI to avoid difficult decisions
FI should only be used when you genuinely cannot assess something, not when you are unsure about the correct classification. If you can see a defect and assess its severity, code it. FI is for situations where you cannot physically see or test the item in question.
Vague observation descriptions
Writing "bonding inadequate" or "needs attention" without specifying what, where, and which regulation. Every observation should be specific enough that another competent person could read it and understand exactly what was found and what needs to be done.
Inconsistent coding within the same report
Coding the same type of defect as C2 on one circuit and C3 on another without a clear reason. If missing RCD protection on the kitchen circuit is C2, it should be C2 on the bathroom circuit as well. Consistency demonstrates professional judgement.
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Frequently Asked Questions About Observation Codes
Does a single C1, C2, or FI observation make the entire EICR unsatisfactory?
What is the difference between C2 and C3?
When should I use an FI code instead of a classification code?
How long does a landlord have to fix C1, C2, and FI observations?
How do I code the absence of an AFDD or 30 mA RCD on lighting circuits under A4:2026?
Can I change an observation code after the EICR has been issued?
What is the most common C2 observation found on domestic EICRs?
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