C1: danger present
Something could hurt someone right now, like live parts you can touch on a broken socket or a damaged fitting. We make it safe before we leave, with your say-so, usually by disconnecting the circuit or the fitting until it can be repaired properly.
C2: potentially dangerous
Not an immediate danger, but something that could become one, for example if a fault developed. It needs putting right urgently, and the report counts as failed until it is.
C3: improvement recommended
Not dangerous, but not up to today's standard. Older installations often pick up a few C3s for things that were fine when they were fitted. A C3 on its own doesn't fail the report. It's worth planning for, not panicking about.
FI: further investigation
Something we couldn't fully check during the inspection needs looking into, like a circuit that couldn't be traced or a test result that needs a closer look. Like a C1 or C2, it makes the report unsatisfactory until it's been looked into.
Pass or fail
The report is satisfactory if it has no C1, C2 or FI codes. Any one of them makes it unsatisfactory. Once the work is done and re-tested, you get confirmation that the installation is now satisfactory.
If you're a landlord
In England, an unsatisfactory report means the remedial work, or the further investigation, has to be done within 28 days of the inspection, or sooner if the report says so. You then need to give written confirmation that it's done to your tenants and the local council within 28 days of the work.
