Hi
I've invested on a EICR Codebreaker Via Napit earlier this year and had the previous version for 17th Edition which is a Good bit of Kit to add to your tool bag, I'm sure NICEIC & other Bodies have their own versions for members or non members
So regarding C2 or C3, 2nd floor flat you probably wont dangling a extension lead out your window to clean your car, but ground floor & 1st floor its likely as i've seen it so many times, so on 1st Floor & ground Floor, I Code C2, BS 7671 522.6.202, sockets which can be used outdoors
Also no cables with no mechanical protection ie. not in steel conduit ot the likes of, in stud walls or cables buried in walls less than 50mm as most solid walls are 100mm so either side will be still venerable for a cable to be penetrated by a nail or rouge Screw by others C2, BS 7671 411.3.3
I don't look for making extra work for a EICR's or extra money for the sake of it etc, but safety of the Property and Safety Life, as you can not put a cost to someone life, so to clients to spend a few hundreds to get up to date as RCD's are life savers regarding age of installation, I always recommend on a inspection to upgrade any issues to bring installation to a good standard RCD's or RCBO's to future proof for now and btw this is just my opinion & 90% of my clients & Landlords & Landladies will also agree.
As I also do work for Local Governments & Authorities they now have started to replace D.B.'s when tenants leave their properties if any additional circuits needed all D.B. to have RCBO's and S.P. as standards to meet 18th Edition
Kind Regards
Tony Jelade Electrical Services