Does a C3 observation make an EICR "unsatisfactory"?

No. Only C1 ("Danger present") and C2 ("Potentially dangerous") observations make the overall EICR assessment "unsatisfactory". An EICR with only C3 observations remains "satisfactory" overall — the responsible person is informed of recommended improvements but no urgent or remedial action is required.

Can I assign C3 to a defect that's borderline C2?

No. The code follows the evidence: if the condition is potentially dangerous it is C2, and calling it C3 to keep the report satisfactory misreports the installation.

How long does a landlord have to address a C3?

The Electrical Safety Standards in the Private Rented Sector and Social Rented Sector (England) Regulations 2020 require remedial work on C1 and C2 observations, and any further investigation the report calls for (FI), within 28 days. C3 observations are recommendations, not legal requirements — the landlord may choose to address them at the next maintenance opportunity, at the next EICR, when refurbishing, or not at all. The inspector should still record the C3 clearly so the responsible person can make an informed decision.

Is "no AFDD" automatically a C3 under A4:2026?

It depends on the location. Since A2:2022, Regulation 421.1.7 requires AFDDs on single-phase socket-outlet circuits up to 32 A in high rise residential buildings, HMOs, purpose-built student accommodation and care homes, and recommends them elsewhere; Section 710 prohibits them in medical locations of group 0, 1 and 2 and on medical IT systems. Where AFDDs are recommended but not required, absence is typically a C3 in the existing installation context. Where they are required and missing, the classification is C2 because the protection deficiency creates potential danger.

Should pre-2008 plastic consumer units be C2 or C3?

It depends on context. Regulation 421.1.201 mandates non-combustible consumer units in domestic premises (introduced January 2016 in BS 7671:2008+A3). For a plastic consumer unit installed pre-2016: in a normal owner-occupied dwelling away from an escape route, C3 is generally appropriate. In an HMO, in an escape route, under a wooden staircase, or with visible heat damage / signs of arcing, C2 becomes the correct classification because the combustibility presents potential danger in that specific context. Document the rationale either way.

Can I list a C3 observation in Section K alongside C1/C2 observations?

Yes — all observations regardless of classification are recorded in Section K of the EICR. Each gets a single classification code. The overall assessment is "unsatisfactory" if any C1 or C2 is present. C3 and FI observations are advisory under the A4:2026 model form, so a report with only C3 or FI observations is "satisfactory."

Do I need to take photos of C3 observations?

Industry good practice but not BS 7671-mandated. Photos help the responsible person understand the recommendation and make commissioning decisions easier later. They also protect the inspector if the classification is later disputed. Every modern digital EICR app supports per-observation photos — use them for C3s as well as C1/C2s.

EICR OBSERVATION CODE

EICR Code C3 — Improvement Recommended

C3 means the installation departs from current BS 7671 — but neither danger nor potential danger is present. Unlike C1 and C2, a C3 does NOT make the EICR "unsatisfactory". This guide explains the exact decision boundary, the most common C3 observations on UK reports, and how to write a C3 that the responsible person will actually act on.

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9 min readUpdated 2026-10-28Andrew Moore, Founder of Elec-Mate

Written and reviewed by Andrew Moore, founder of Elec-Mate, against BS 7671:2018+A4:2026, IET Guidance Note 3 and the IET On-Site Guide.

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The short answer

What does C3 mean on an EICR?

C3 means "Improvement recommended". Part of the installation does not meet the current edition of BS 7671 but is not dangerous, for example an older plastic consumer unit or Type AC RCDs. A C3 does not make the report unsatisfactory, and landlords are not legally required to fix it, though it is worth doing when other work is done.

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Key takeaways

01C3 means "Improvement recommended." The installation departs from current BS 7671 but does not create danger or potential danger — neither C1 nor C2 applies.
02C3 observations do NOT make the overall EICR assessment "unsatisfactory". A report with only C3 observations remains "satisfactory" overall.
03C3 is only for conditions that are not dangerous. If the evidence shows potential danger the code is C2, whatever the commercial pressure to keep a report satisfactory.
04Common C3 territory: work that met the edition in force when installed but not the current one, such as a pre-2016 plastic consumer unit away from an escape route, missing socket RCD protection where no socket could serve equipment outdoors, Type AC RCDs, or no AFDDs where they are only recommended.
05A well-written C3 still recommends specific improvement work — vague "could be improved" notes have no remedial value and undermine the report.
06C3 observations don't trigger the 28-day PRS Regs remedial window in rented properties — but a landlord may still choose to address them at the next maintenance opportunity.

01 · EICR Observation Code

What C3 Means

C3 is defined as "Improvement recommended." The classification applies where an observed condition departs from the current edition of BS 7671 in a way that an improvement would address, but the departure does not create danger or potential danger.

C3 keeps the EICR "satisfactory"

Unlike C1 and C2, a C3 observation does not change the overall report assessment. An EICR with only C3 observations is recorded as "satisfactory" — the responsible person is informed of potential improvements but no urgent action is required.

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02 · EICR Observation Code

The C3 Decision Rule (Strict)

The decision is simpler than it looks: decide whether the condition is dangerous before deciding how serious it is.

C3 only when there is no danger

C3 ("Improvement recommended") is for departures from the current edition that are not dangerous now and would not become dangerous under foreseeable conditions. If the evidence points to danger present, the code is C1; to potential danger, C2.

This is to stop commercial pressure (or politeness) from softening serious findings into reassuring "improvement" recommendations. Every inspector encounters the temptation: "the report looks better with no C2s." Downgrading a potentially dangerous condition to C3 misreports the installation.

03 · EICR Observation Code

Genuine C3 Observations

Conditions where C3 is the correct classification — improvement is genuinely recommended but no danger, present or potential, exists:

Wiring installed under a previous edition of BS 7671 that remains safe, but uses now-superseded methods (e.g. older colour codes in industrial wiring where a clear ID label is present and circuits are functional).
A consumer unit with spare ways but no AFDD where AFDDs are recommended (not required) under A4:2026.
Type AC RCDs serving circuits that may carry DC residual current. Regulation 531.3.3 now limits Type AC to fixed equipment with no DC component, so Type A is the improvement.
Missing 30 mA RCD protection on socket-outlets in an older installation where no socket could reasonably supply equipment outdoors (Regulation 411.3.3).
A pre-2016 plastic consumer unit in good condition, away from an escape route (Regulation 421.1.201 is not retrospective).

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04 · EICR Observation Code

NOT C3 — These Are C2

These observations are sometimes mis-classified as C3 but should be C2 because the condition is potentially dangerous, not merely a "departure from current standards":

Missing main protective bonding to extraneous-conductive-parts — C2 (potentially dangerous under fault conditions), not C3.
Plastic consumer unit in HMO escape route — C2 (combustibility / Regulation 421.1.201 with HMO context), not C3.
Missing RCD on a socket-outlet that could reasonably supply equipment outdoors — C2 (Regulation 411.3.3), not C3.
Damaged but contained cable sheath — C2 (degraded protection, foreseeable progression to exposed conductors), not C3.
Borrowed neutral across separate final circuits — C2 (potential for unexpected energisation during isolation), not C3.

The downgrade temptation

If you find yourself reaching for C3 to "keep the report satisfactory," the chances are high that the evidence supports C2. Ask whether the condition could become dangerous under foreseeable conditions; if it could, it is C2.

05 · EICR Observation Code

How to Write a C3 That Gets Acted On

C3 observations don't trigger the legal remedial timeline that C1/C2 trigger — so the responsible person can choose to ignore them. A well-written C3 helps them make an informed decision rather than dismissing the recommendation:

State the specific BS 7671:2018+A4:2026 regulation the installation departs from.
Describe the practical benefit of the improvement (e.g., "fitting a Type A RCD would extend protection against DC fault current components from modern electronic loads").
Note the typical timeline for addressing the improvement (e.g., "at the next scheduled maintenance opportunity, or sooner if the consumer unit is replaced for any other reason").
Avoid vague language like "this could be improved" — name the specific improvement.
Where the C3 relates to a pre-A4 installation, note that the previous edition was complied with at the time of installation — this avoids implying the original installer was non-compliant.

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