Each safety observation on an Electrical Installation Condition Report (EICR) gets one classification code. The code tells the person who ordered the report how urgently something needs doing. The codes come from the model EICR in BS 7671. The industry reference for applying them is Electrical Safety First's Best Practice Guide 4 (BPG4), produced with input from bodies including the IET, NICEIC and NAPIT. Issue 7.4, dated August 2026, takes account of BS 7671:2018+A4:2026.
The four codes
Danger present
People using the installation are at risk now, so remedial action is needed immediately. Where it's practicable, make it safe on discovery with the client's agreement, and tell them straight away in writing.
Potentially dangerous
It isn't dangerous at the moment of inspection, but a fault or some other foreseeable event would turn it into an immediate danger. Remedial action is urgent.
Improvement recommended
Not a source of immediate or potential danger, but putting it right would make the installation safer. It is advisory.
Further investigation
You found a possible safety issue you couldn't classify within the agreed extent and limitations. The A4:2026 form says further investigation is advised.
Give each observation one code only. If more than one could apply, BPG4 says use the most serious.
How the codes decide the overall result
Under A4:2026 the rule is simple. Any C1 or C2 observation makes the overall assessment unsatisfactory. C3 and FI observations are advisory and don't change it. The A4 model form now splits the observations section in two: one list for C1 and C2 items, which drive the outcome, and a separate list for C3 and FI items, which don't. BPG4 adds that with no C1 or C2 observations it wouldn't be reasonable to call an installation unsatisfactory.
That is a change for FI. The notes on the A2:2022 model form told inspectors to mark an FI observation as unsatisfactory, and the code read as further investigation required without delay. The IET says A4 separated FI and C3 from C1 and C2 to make it clear they don't lead to an unsatisfactory outcome.
Typical examples of each code
These are paraphrased from the tables in BPG4 Issue 7.4. They aren't exhaustive, and the person signing the report is responsible for its content. BPG4 expects you to be able to justify any departure from it.
| Code | Examples |
|---|---|
| C1 | Live parts that can be touched: a missing circuit-breaker with no blank fitted, a badly damaged accessory, or conductors with missing or damaged insulation. Metalwork made live by a fault. Incorrect polarity at the origin. |
| C2 | No reliable means of earthing, or a gas, oil or water pipe used as the earth. No effective main bonding to metal pipes or other extraneous-conductive-parts entering the building. A socket-outlet with no earth. No RCD for sockets likely to supply equipment used outdoors, or for a socket circuit in a room with a bath or shower. Zs too high for the device to disconnect in the time required when it was installed, with no RCD on the circuit. A borrowed neutral, a broken ring or a ring cross-connected with another circuit. Insulation resistance below 1 MΩ to earth. Connections showing signs of overheating. |
| C3 | No RCD for a socket that is unlikely to supply outdoor equipment and doesn't serve a bathroom. No RCD on lighting circuits in a home. Cables less than 50 mm deep in a wall with no RCD and no other protection. A Type AC RCD where a Type A is needed. A plastic consumer unit, not in a non-combustible enclosure, under a wooden staircase or on the only escape route. No AFDD in an HMO, a high-rise residential building, purpose-built student accommodation or a care home. |
Findings that don't take a code
Issue 7.4 names three kinds of finding that shouldn't be coded:
- Observations worth mentioning that aren't non-compliances, such as a consumer unit fitted high up, or no AFDDs in an ordinary house.
- Non-compliances only: departures from BS 7671 that don't give rise to danger and needn't be recorded, such as old cable colours, or a plastic consumer unit that isn't under stairs or on an escape route.
- Myths: things that aren't non-compliances at all, such as rewireable fuses that still protect the circuit properly, circuit-breakers to BS 3871, or sockets without switches.
Using FI properly
Periodic inspection isn't fault-finding. BPG4 says that in a domestic installation you should generally be able to code every observation without further investigation. FI is for a potential safety issue that the agreed extent or limitations stopped you getting to the bottom of.
The IET gives two examples of FI used wrongly. An unidentified circuit breaches Regulation 514.8.1, so code it: tracing the circuit is remedial work. An insulation resistance reading below 1 MΩ fails Table 64, so code it: finding the cause is fault-finding.
Writing observations that hold up
- Describe what you found, not the repair. Price the remedial work on a separate quote.
- Write for the person who ordered the report, in plain language, with the schedule reference. Photographs can be attached.
- Record faults on the distributor's or supplier's intake equipment, but don't let them decide the outcome unless live parts are accessible. Advise the client to report dangerous intake equipment urgently; BPG4 points to the 105 number.
- Make the recommended date for the next inspection conditional on C1 items being fixed immediately and C2 items urgently.
- An installation built to an earlier edition isn't unsafe simply because it doesn't meet the current one.
Codes on rented homes
In England, the government's guidance for landlords says C1 and C2 observations need remedial work, C3s don't have to be acted on, and FI items must be investigated. That guidance dates from November 2025, before A4:2026 made FI advisory, so describe any FI precisely. Our guide to landlord EICRs in England covers the deadlines.