Choosing an EICR code is not a matter of matching every defect to a memorised list. The inspector must assess the condition found, the credible route to harm and the effectiveness of the protective measures.
For an inspection carried out now, the assessment basis is BS 7671:2018+A4:2026. That does not mean every older installation must be upgraded automatically. The note in Chapter 65 recognises that compliance with an earlier edition does not necessarily make an installation unsafe for continued use.
What each EICR classification means
The classification descriptions appear in the guidance accompanying the model Electrical Installation Condition Report:
| Code | Meaning | Required response | Effect on report |
|---|---|---|---|
| C1 | Danger present | Immediate remedial action required | Unsatisfactory |
| C2 | Potentially dangerous | Urgent remedial action required | Unsatisfactory |
| FI | Further investigation required without delay | Investigate promptly to establish whether danger exists | Unsatisfactory |
| C3 | Improvement recommended | Improvement would enhance safety | Satisfactory if no C1, C2 or FI exists |
Regulation 653.1 requires a report to be provided following periodic inspection and testing. The report records the extent of the work, its limitations, test results, observations and the overall assessment.
“C1 is dangerous right now.”
That is a useful starting point, but coding still requires engineering judgement. The classification must follow the actual risk, not a convenient label or the age of the equipment.
For a broader revision summary, see EICR Coding Explained: C1, C2, C3 and FI.
C1: danger is already present
C1 applies where someone can encounter danger in the installation’s present condition. Typical examples include:
- accessible live conductors
- missing consumer-unit blanks that permit access to live parts
- a broken accessory exposing live parts
- an unenclosed live connector block within reach
- severe damage leaving energised conductor material accessible
Immediate action is required. The inspector should warn the person responsible clearly and in writing. If authorised, competent and able to do so safely, the danger may be removed by isolating the affected circuit or making the condition safe. A C1 must never be left merely as a line on a report without the danger being communicated.
The “one action” mnemonic — one touch leads directly to injury — can help candidates visualise C1, but it is not a formal classification rule. The real question is whether danger is present now.
C2: a credible fault or event would create danger
C2 describes a condition that is not immediately dangerous but could become dangerous under reasonably foreseeable circumstances. Examples may include:
- an unearthed metallic accessory that could become live following an insulation fault
- inadequate fault protection where the required disconnection time may not be achieved
- absence of required 30 mA RCD additional protection where the circumstances create a credible shock risk
- damaged wiring with basic insulation exposed and vulnerable to further damage
- serious thermal damage that has not yet exposed live parts
The inspector must evaluate the entire protective arrangement. A measured Zs above the relevant maximum in Table 41.2, 41.3, 41.4 or 41.5 cannot be coded sensibly without confirming the protective device, required disconnection time, conductor arrangement and any RCD protection.
The “two things must happen” idea is another teaching aid, not a BS 7671 test. Some C2 conditions involve one foreseeable event; others involve several. Code according to the potential danger, not the number of imagined steps.
For the relationship between Ze, Zs and fault-current measurements, read Ze, Zs, PFC and PSCC: What Each Test Measures and Where.
FI: uncertainty about potential danger, not unfinished work
FI is frequently misused as a holding code. It is appropriate only when:
- potential danger is reasonably suspected;
- the inspection could not establish its safety significance; and
- investigation is required without delay.
A low insulation-resistance result might justify FI where connected equipment or inaccessible wiring prevents the inspector from establishing the cause and risk within the agreed periodic inspection. Similarly, an abnormal protective-conductor result may require investigation where the circuit arrangement cannot be confirmed.
However, FI is not a substitute for a known C2. If the measurements already show that fault protection is ineffective, the inspector has enough information to classify the danger. Nor should FI be entered simply because the inspection was under-priced or time ran out.
Periodic inspection identifies and classifies conditions. Fault-finding and remedial work may be a separate contract, but the initial inspection must still include the work reasonably necessary to reach a defensible assessment.
C3: improvement would enhance safety
C3 applies where improvement is recommended but the condition is not dangerous or potentially dangerous and does not require investigation without delay.
A common example is a serviceable plastic consumer unit in domestic premises. Regulation 421.1.201 now requires consumer-unit enclosures and similar switchgear assemblies in domestic premises to be manufactured from non-combustible material or enclosed in a non-combustible cabinet. A plastic unit installed under an earlier edition is not automatically unsafe; in otherwise satisfactory condition, it will normally attract C3.
That changes if there is overheating, damage, accessible live material or another defect. The code follows the condition found, not the word “plastic”.
Other possible C3 observations include wiring exposed to an external influence for which its sheathing is unsuitable, before deterioration has created potential danger. Once cracking, exposed insulation or loss of protection is present, a higher classification may be justified.
Use the model EICR schedule as a checklist
The IET model EICR includes a Schedule of Inspections whose entries point towards relevant BS 7671 requirements. It should be used systematically so that protective measures, earthing, bonding, distribution equipment, circuits and accessories are not overlooked.
Regulation 651.2 requires periodic inspection to be supplemented by appropriate testing. The schedule is therefore more than an office form completed from memory: it is the structure for the inspection.
Record observations precisely. “Does not comply” is weak. A useful entry identifies:
- the location and circuit
- the condition found
- the relevant requirement
- the danger or loss of protection
- the classification allocated
Coding does not change the safe test sequence
Where tests are needed to establish an observation, the sequence remains safety-critical. Appropriate Chapter 64 tests are applied during periodic inspection through Regulation 651.2.
After safe isolation, carry out dead tests before live tests. Continuity under Regulation 643.2 comes before insulation-resistance testing under Regulation 643.3. Polarity is confirmed before energisation, and live measurements are then undertaken only where necessary and under controlled conditions.
The practical order is:
- safely isolate and prove dead;
- carry out protective-conductor continuity testing;
- carry out insulation-resistance testing;
- confirm polarity;
- restore the installation safely;
- undertake necessary live tests, including loop impedance, RCD operation and prospective fault current.
GS38-compliant voltage indicators and proving units support safe isolation, while the Electricity at Work Regulations 1989 govern the precautions required to prevent danger. Never perform a live test merely to fill a certificate box when the same conclusion can be reached safely by another method. The safe isolation and GS38 guide explains the prove–test–prove procedure.
Limitations are not observation codes
A limitation records an agreed or unavoidable part of the installation that was not inspected or tested. Regulation 651.1 requires the extent and limitations of the periodic inspection to be agreed with the person ordering the work and recorded.
Valid examples might include:
- fixed machinery preventing access
- an inaccessible high-bay installation where suitable access was excluded from the agreed scope
- areas that cannot be entered safely
- circuits that cannot be isolated because of an agreed critical service
“Could not be bothered to move furniture” is not a defensible limitation. Nor can a limitation be used after a suspicious result to avoid deciding whether further investigation is required.
A satisfactory assessment applies only to the installation within the recorded extent. Extensive limitations materially reduce what the client can rely upon.
What happens after an unsatisfactory EICR
C1, C2 and FI observations make the report unsatisfactory. Remedial work should then be verified and documented appropriately.
An EIC may be required for work covered by Regulation 644.1, while an MEIWC may be appropriate under Regulation 644.4.201 for an addition or alteration to an existing circuit. The distinction is covered in EIC, Minor Works or EICR: Which Document Do You Issue?.
The original EICR does not automatically become satisfactory. It remains a record of the installation on the inspection date. Evidence of completed remedial work can be attached or referenced, and a complete repeat EICR is not necessarily required unless the client, insurer or scope of the work calls for one.
How 2391 Prep Fits Into This
The 2391 Inspection & Testing Pro app covers EICR classifications in its Certification and Reporting material, alongside inspection procedures, test-result interpretation, earth fault loop impedance and prospective fault current.
It includes 556 practice questions across 7 subject areas, 4 working calculators, 15 quick reference cards and 6 field tools.
The City & Guilds 2391-52 exam contains 60 questions, allows 120 minutes and has a 75% pass mark. It is an OPEN BOOK exam, so practise locating Part 6 requirements, the Chapter 65 note, maximum Zs tables and model-form guidance quickly rather than relying only on memorised example codes.
