C1, C2, C3: what your EICR codes actually mean... and when a "fail" isn't dangerous

You've had your EICR back, it says "unsatisfactory" in bold, and there's a list of jobs with letters and numbers next to them. And somewhere in the back of your mind is the thought most landlords have: is this electrician telling me the truth, or drumming up work?

Fair question. So here's what the codes actually mean, which are a real fail, and how to spot a careful inspection from a padded one.

The four codes, in plain English

Every observation on an EICR gets one of four codes:

C1... danger present. Someone could get hurt right now. Think exposed live parts. A decent inspector will often make a C1 safe before leaving the property. This is the serious one.
C2... potentially dangerous. Not an immediate risk today, but it could become one, so it needs putting right. This is the code landlords argue about most... more on that below.
C3... improvement recommended. Not dangerous. A "you could do better" note, not a fault. A C3 on its own does not fail your report.
FI... further investigation. The inspector found something that needs a closer look before it can be coded properly. Not a fail in itself, but it can't just be ignored.

What actually makes a report "unsatisfactory"

This is the bit worth getting straight: a report is marked unsatisfactory only if it has a C1, a C2, or an FI. A report with nothing but C3s is satisfactory... you've passed. So if yours came back "unsatisfactory" and every item is a C3, something's been coded wrong, and you're within your rights to ask why.

The C2-versus-C3 argument... where I'll be straight with you

Here's the honest bit. The line between C2 and C3 is a judgement call, and reasonable, competent electricians genuinely do land on different sides of it. The classic one is an older consumer unit with no RCD protection: one inspector calls it C3 (improvement), another calls it C2 (potentially dangerous, so a fail). Both can defend their view.

The problem is that a C2 turns a pass into a fail... and a fail means work. So when someone's borderline calls all seem to land on C2, and the quote to fix them is sitting right underneath, you'd be forgiven for raising an eyebrow.

My rule is simple: if something is genuinely advisory rather than dangerous, I'll tell you it's a C3 and I'll tell you why. And if you've got a report from another firm that you're not sure about, I'm happy to read it over and give you a straight second opinion. If they were right, I'll say so.

What you legally have to do

For anything coded C1, C2 or FI, you must get the remedial work done within 28 days of the inspection (or sooner if the report says so), then get written confirmation it's sorted. C3s are optional... worth doing, but no legal deadline. Miss the real duties and the penalty now runs up to £40,000 per breach, so the codes that matter are worth getting right... which is another reason a coding you can trust matters.

Slough's rental stock and where the codes land

A lot of what I see failing round here is predictable from the housing: the ex-council flats and terraces still carrying an old board with no RCD, the Victorian conversions where decades of "tidying up" have left borrowed neutrals. None of it is a reason to panic... it's just where the C2s tend to sit, and knowing that helps me tell a genuine one from a lazy one.

Want a second opinion?

I'm a NAPIT-registered electrician based in Slough, and I do EICRs and remedials across the Thames Valley. If you want an inspection that codes things honestly, or a straight read on a report another firm gave you, see my inspection and testing page or get in touch for a free, no-obligation quote. If it's your fuse box that's the sticking point, my fuse box replacement page explains when a board really does need doing... and when it doesn't.