EICR codes explained: C1, C2, C3 and FI

C1: danger present

C1 means there is a risk of injury now: exposed live parts someone could touch, for example, or a socket with its cover broken off. The inspector should tell you straight away and, with your agreement, make it safe on the spot, usually by isolating the circuit. Any C1 makes the report unsatisfactory, and the fix is urgent.

C2: potentially dangerous

C2 means something is not dangerous at this moment but could become so if a fault develops. Missing main bonding to the gas pipe, or sockets that could supply equipment outdoors without RCD protection, are typical. A C2 also makes the report unsatisfactory and needs remedial work. For a landlord, that means within 28 days or a shorter period set on the report.

C3: improvement recommended

C3 marks something that does not meet the current edition of the wiring rules but is not dangerous, such as an older plastic consumer unit in good condition or missing circuit labels. It does not make a report unsatisfactory. The government guidance for landlords says a C3 does not require remedial work, although acting on it improves safety.

FI: further investigation

FI is used when the inspector has seen a possible safety issue but could not fully assess it within the limits of the inspection. The IET stresses that it should be used rarely, and not as a substitute for coding a fault that can be identified, such as an unidentified circuit or a low insulation reading.

Amendment 4 to BS 7671, published on 15 April 2026, changed the wording to "further investigation is advised" and, like C3, an FI no longer makes a report unsatisfactory by itself. The landlord rules have not caught up with that change: the government guidance, written in November 2025, still says that where an inspector identifies further investigative work, the landlord must make sure it is carried out within 28 days. Treat an FI on a rented property as a job to book.

What makes a report satisfactory or unsatisfactory

On reports written to Amendment 4, the observations are split into two parts: C1 and C2 in the first, C3 and FI in the second. Any entry in the first part makes the report unsatisfactory. If the first part is empty, the report is satisfactory, whatever sits in the second.

Reports written before and after April 2026

Amendment 4 became the only current version of BS 7671 on 15 October 2026, when the previous edition was withdrawn. A report written earlier on the older form may show an unsatisfactory result because of an FI alone. It stays valid for the period stated on it; the change does not make anyone redo a report.