C2 or C3? Making consistent EICR coding decisions
Two competent inspectors can look at the same installation and produce different reports. The gap is almost always at the C2 and C3 boundary, and it is the difference between a satisfactory report and a landlord facing 28 days of remedial work.
Updated 2026-09-30
What each code actually means
The codes describe risk, not age and not preference. Getting that straight removes most of the disagreement.
- · C1 — danger present, risk of injury now. Immediate action required, and you tell the person responsible before you leave
- · C2 — potentially dangerous. Safe as it stands, but a foreseeable fault or event would make it dangerous
- · C3 — improvement recommended. Not dangerous and no fault would make it so, but it falls short of current standards
- · FI — further investigation required. You cannot determine the risk without more work
The question that decides it
Ask: is there a single foreseeable failure or event that turns this observation into a danger? If yes, it is a C2. If the installation would still be safe after that event, it is a C3.
A missing earth at a metal light switch is a C2 — one insulation failure makes the faceplate live. No RCD on a lighting circuit in a modern house is a C3 — nothing about it becomes dangerous without a separate fault, and the circuit complied when installed.
Worked examples at the boundary
These are the cases that generate the most argument between inspectors and contractors.
- · No RCD on a socket circuit likely to supply outdoor equipment: C2
- · No RCD on an internal socket circuit in an unoccupied commercial unit: C3, sometimes C2 depending on use
- · Plastic consumer unit in a domestic property, otherwise sound: C3
- · Plastic consumer unit with signs of heat damage at the terminals: C1 or C2 depending on severity
- · Missing supplementary bonding in a bathroom with no RCD protection: C2
- · Missing supplementary bonding in a bathroom where all circuits are 30 mA RCD protected and main bonding is present: C3
- · Cables buried less than 50 mm in a wall without mechanical protection or RCD: C2
- · No circuit identification or schedule at the board: C3
- · Exposed live conductors at a damaged accessory: C1
Age is not a code
An installation is inspected against the standard in force when it was installed, with current requirements used to judge safety. Something that was compliant in 1998 and remains safe is not automatically a C3, and it is certainly not a C2.
Writing 'does not comply with BS 7671:2018+A4:2026' against every rewireable fuse in a functioning installation inflates the report and damages trust in the profession.
What over-coding costs everybody
Coding a C3 as a C2 makes the report unsatisfactory. Under the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 that starts a 28-day remedial clock, and a landlord who does not comply faces penalties of up to £30,000.
It also invites a second opinion, and a report that is overturned follows you. Under-coding is worse still: if somebody is injured by something you saw and coded C3, you will be asked to justify it.
Using FI properly
FI is not a way to avoid a decision. It is for genuine cases where you cannot establish the risk — a circuit you could not test because it serves equipment that must not be switched off, or evidence of concealed damage you cannot access.
Under Amendment 4, FI is handled as an advisory outcome on the model forms, but any installation with an outstanding FI cannot be regarded as satisfactory until the investigation is complete.
Evidence and consistency
Photograph every observation. A picture attached to the report removes almost all argument about whether the code was justified, and Amendment 4 explicitly anticipates photographic and thermal imaging evidence being attached.
Write the observation in plain language, state the risk, and cite the regulation. 'No RCD protection to socket-outlets likely to supply equipment outdoors, risk of electric shock, Regulation 411.3.3' tells the reader everything. 'No RCD' does not.