C1 means danger is present and the installation must be made safe immediately. C2 means potentially dangerous and needs urgent repair. C3 means improvement is recommended but not required. Any C1 or C2 makes an EICR unsatisfactory, a report with only C3s can still be satisfactory, and since BS 7671 Amendment 4 an FI on its own does not make it unsatisfactory either.
Getting an EICR report back and seeing a code you do not recognise next to a finding is a common moment of confusion. An EICR does not simply pass or fail. Instead, anything an electrician finds during the inspection is recorded against a specific classification code, and what that code is determines how urgently it needs sorting out. Here is what each one actually means.
The Classification Codes, in Order of Seriousness
| Code | Meaning | Effect on the report | What happens next |
|---|---|---|---|
| C1 | Danger present | Unsatisfactory | Made safe on the spot, before the electrician leaves |
| C2 | Potentially dangerous | Unsatisfactory | Urgent repair; landlords have 28 days |
| C3 | Improvement recommended | Can still be satisfactory | Worth planning in, not urgent |
| FI | Further investigation needed | Depends on what the investigation finds | Arrange the investigation; landlords have 28 days |
C1: Danger Present
This is the most serious classification. It means there is a risk of injury right now, for example exposed live parts that could be touched, or a fault that presents an immediate fire or shock risk. When a competent electrician identifies a C1 during an inspection, standard practice is to make the installation safe on the spot, before leaving the property, even if that means isolating a circuit temporarily until proper repairs can be scheduled.
C2: Potentially Dangerous
A C2 means a defect that does not present an immediate danger but could become one, often because a safety feature that should be in place is missing or not working correctly. A common example is a socket likely to be used for equipment outdoors, such as a lawnmower or pressure washer, with no RCD (residual current device) protection. An RCD cuts the power in a fraction of a second if current leaks to earth, which is what protects you if a cable gets damaged outside. The socket might work perfectly well day to day, but without that protection a single fault could give a serious shock. C2 items need urgent attention but do not usually require work on the same visit. Missing main bonding to the gas and water pipes is normally coded C2 as well, and our guide to gas and water bonding explains what is required.
C3: Improvement Recommended
A C3 is the least serious code. It flags something that does not meet current wiring regulations but was often acceptable under older standards at the time it was installed, and does not present a safety risk in itself. A report with only C3 observations can still be issued as satisfactory. Many C3 findings relate to things like ordinary indoor sockets in an older installation that have no RCD protection, or a plastic consumer unit fitted under a wooden staircase or on the only way out of the property. Plastic units haven't been allowed in new home installations since 2016, but one fitted anywhere else doesn't get a code at all.
FI: Further Investigation
Occasionally an inspector cannot fully assess something without additional intrusive work, for example if a cable run is concealed in a way that cannot be tested without opening up a wall. This is flagged as FI. Since the 2026 update to the wiring regulations (BS 7671 Amendment 4), an FI means further investigation is advised, and on its own it does not make the report unsatisfactory.
How Codes Affect the Overall Result
The report itself is marked either satisfactory or unsatisfactory. Any C1 or C2 code makes the report unsatisfactory until the relevant work is completed and the installation is retested. A report with only C3 or FI observations, and no C1 or C2, can be issued as satisfactory, though it is still worth addressing C3 items over time rather than letting them accumulate.
What Remedial Work Involves After an Unsatisfactory EICR
An EICR with a C1 or C2 is often described as a "failed EICR". Remedial work is the repair that clears those codes. The most common remedial jobs are:
- Replacing cracked, scorched or loose sockets, switches and fittings
- Adding RCD protection, which often means a consumer unit replacement
- Fitting or upgrading main bonding to the gas and water pipes
- Tightening or remaking loose and overheating connections
- Correcting reversed polarity or missing earths on individual points
- Investigating and repairing faults flagged as FI
You do not need a whole new EICR afterwards. The electrician who does the work issues a Minor Works Certificate for repairs to existing circuits, or an Electrical Installation Certificate if a new consumer unit or circuit is fitted, and that paperwork together with the original report shows the defects have been put right. Our guide to electrical certificates explained covers each document. The remedial work does not have to be done by the electrician who carried out the inspection, so ask for an itemised quote that lists each code it clears.
What Landlords Specifically Need to Do
If you are a landlord and your EICR comes back with a C1 or C2, the regulations require the relevant work to be carried out within 28 days of the inspection, or sooner if the report specifies a shorter period, and GOV.UK's guidance says any FI items must be investigated in the same window. Within 28 days of the work being finished, you then need to send written confirmation from the electrician to both your tenant and the local council, whether or not the council has asked for it. We cover the full set of legal obligations, including deadlines and penalties, in our guide to the landlord electrical safety certificate.
When a Repeated C2 Points to a Bigger Job
Occasionally, an installation comes back with multiple C2 findings across several circuits, or the same category of fault keeps appearing on successive inspections. When that happens, it is often a sign that the underlying wiring has reached the end of its useful life, and patching individual faults one at a time is not the most cost-effective route. In that situation, it is worth discussing whether a partial or full rewire makes more sense than repeated remedial visits. Our guide on full rewire versus partial rewire covers how to weigh that decision.
Getting the Work Done
Whatever code your report comes back with, the priority is getting an accurate, honest assessment from someone who explains clearly what was found and why. Our team carries out EICR inspections across Tunbridge Wells and Kent, and where the scope allows, we can complete C1 and C2 remedial work on the same visit so your certificate can be issued without unnecessary delay. For prices and timings, see our guides to EICR costs in Tunbridge Wells and Kent and how long an EICR takes. Find out more about the full inspection process on our EICR and electrical testing page, or get in touch for a free quote.