EICR Codes Explained: C1, C2, C3 and FI

If you have ever looked at an Electrical Installation Condition Report, better known as an EICR, you will have spotted little codes next to the observations. C1, C2, C3, and sometimes FI. They can look a bit like a secret language, but the idea behind them is simple.

Each code is just the electrician's shorthand for how serious a problem is, and how quickly it needs sorting. This guide explains what each one means in plain English, what you should do if you see it on your report, and how the codes decide whether your installation passes or fails. Whether you are a landlord, a homeowner, or an electrician who wants a clear way to explain the codes to a customer, this covers what you need to know.

Here is the whole thing at a glance, then we will go through each code properly.

What the codes are for

An EICR is a health check for the fixed wiring in a building. An electrician inspects and tests the installation, then writes down anything that is not right. Rather than describe how dangerous each issue is in a long paragraph, they use a short code. That way, anyone reading the report can see at a glance which problems need urgent attention and which are simply worth improving.

There are four codes you will come across. Three of them (C1, C2 and C3) grade how serious a fault is. The fourth (FI) is a bit different, and we will get to it. Let us take them one at a time.

C1: Danger present

C1 means danger present. In plain terms, someone could get an electric shock, a burn, or start a fire right now, just from using the installation as normal. It is the most serious code, and the rarest to see on a well kept property.

A C1 is not something to leave for later. A good electrician will make the danger safe there and then if they can, for example by isolating a circuit or making a live part impossible to touch, and they will note that on the report. But making it safe on the day is a temporary fix. The proper repair still needs doing.

Things that typically get a C1:

• Live parts you can touch, such as a broken socket or light fitting with the wiring exposed.
• A cable with its inner conductors showing.
• A wiring mistake that leaves metalwork, like a boiler case or a light switch plate, live.

C2: Potentially dangerous

C2 means potentially dangerous. The installation is not going to hurt anyone this second, but it could, if something else goes wrong. Maybe a fault develops, or a cable gets damaged, or someone touches two things at the same time. It is a genuine risk, just not an immediate one.

C2 issues need putting right quickly. For rented homes in England, the rule is that C1 and C2 work must be done within 28 days of the report, unless the electrician gives a shorter time. For your own home there is no legal clock, but a C2 is still worth fixing promptly, because the whole point of the code is that the safety net is missing.

Things that typically get a C2:

• No earthing or bonding where it is needed, so metalwork could become live under a fault.
• A circuit with no protective (earth) conductor.
• Damaged cable insulation that is not live and exposed today, but could become a hazard.

C3: Improvement recommended

C3 means improvement recommended. This is the code people worry about the most and need to the least. A C3 is not dangerous. The installation is safe to keep using. It simply means something could be better, usually because the standards have moved on since the installation was first put in.

You do not have to act on a C3. It is a suggestion, not an instruction. Sorting it is often a good idea when you next have electrical work done, but the choice is yours.

Here is the part that matters most: a C3 on its own does not fail the report. A report with only C3 observations is still Satisfactory. So if your EICR came back with a handful of C3s and nothing else, that is a pass.

Things that typically get a C3:

• No RCD protection on older socket circuits that were fine under the rules at the time they were installed.
• A missing circuit chart or labelling at the consumer unit.
• An older style of consumer unit that met an earlier standard.

FI: Further investigation

FI means further investigation. This one is different from the others, because it does not describe a fault at all. It means the electrician found something they could not fully assess on the day, and it needs a closer look before anyone can say whether it is a problem.

Maybe a circuit behaved oddly during testing. Maybe there are signs of past overheating with no obvious cause. Maybe part of the wiring is hidden behind a fixed panel or built in furniture and could not be reached. Rather than guess, the electrician flags it for investigation.

An FI should be followed up without delay. Once someone looks properly, it might turn out to be a C1, a C2, a C3, or nothing at all. Because the safety of the installation cannot be confirmed while the question is open, an FI makes the overall report Unsatisfactory until it has been investigated.

Does your report pass or fail?

At the bottom of every EICR is a single word that matters more than any other: Satisfactory or Unsatisfactory. It tells you whether the installation is safe to keep using or whether it needs work first.

The rule is simple:

• If the report has any C1, C2 or FI, it is Unsatisfactory. Something needs putting right, or looking into, before it can be signed off as safe.
• If the report has only C3 observations, or none at all, it is Satisfactory.

So a whole list of C3s will not fail your report, but a single C1, C2 or FI will. If you are ever unsure why a report came back Unsatisfactory, look for those three codes and it will usually be clear.

What to do if your report has codes

Here is the short version of what each code asks of you.

• C1: act immediately. The danger should be made safe on the day, and the repair booked as soon as possible.
• C2: repair soon, and within 28 days if the home is rented in England.
• C3: optional. Improve it when convenient, no rush.
• FI: arrange the further investigation without delay, then act on whatever it finds.

Once any C1 or C2 work is done, ask the electrician for written confirmation that the installation is now safe. If the property is rented, you also need to give a copy of that confirmation to your tenant, and to the local authority if they have asked for it, within 28 days. Keeping those documents together saves a lot of stress later.

Common questions

Does a C3 mean I failed my EICR?

No. A C3 is Improvement Recommended, and a report with only C3s is still Satisfactory. It is a pass with a few suggestions attached.

What is the real difference between a C2 and a C3?

A C2 could hurt someone if a fault develops, so it has to be fixed. A C3 is safe as it stands and is only a recommendation. The line between the two is about whether there is a real risk of injury, not just an old fashioned way of doing things.

Can I ignore a C2 if the installation seems fine?

No. A C2 means the risk is there even if nothing has gone wrong yet. It is the missing safety net that matters, and the report stays Unsatisfactory until it is dealt with.

Two electricians gave the same issue different codes. Who is right?

It happens. Coding involves judgement, and honest electricians occasionally disagree on borderline cases, usually around C2 versus C3. The industry reference points are BS 7671 and the guidance from Electrical Safety First, and a clear written observation explaining the reasoning is worth more than the code on its own.

A note for electricians

If you carry out EICRs, consistent coding is what keeps your reports credible. The trickiest calls are almost always the C2 versus C3 ones, and the honest answer is that you will not always agree with the next person. When you are unsure, lean on the wording in BS 7671 and the Electrical Safety First best practice guide, and write the observation so the customer understands the why, not just the letter and number.

It also helps to keep the description plain. A homeowner who reads "no RCD protection to socket outlets, improvement recommended" understands their report a lot better than one who just sees "C3". The clearer the wording, the fewer worried phone calls you get afterwards.