The regulations are not retrospective, but that’s a very misleading statement in the context of EICRs. An EICR is carried out using the current version of BS7671 as a reference. It doesn’t matter when the installation was installed or last inspected. I would very much except a 1992 installation to receive multiple C2s and an unsatisfactory report.
Code 4 = does not comply with current edition for new installation has been removed from the EICR as was seen as being misleading, the code C2 means potential dangerous and is not linked to BS7671.
Every edition I have seen of the wiring regulations gives a date after which any thing DESIGNED after must comply, so an installation designed in 1992 has to comply with original 16th Edition. However it uses words like "does not necessarily" as if some building regulations or CENELEC harmonization document requires a change then even if it complies with the edition in force when designed, there may have been other changes which don't allow the continued use.
Over the years earth bonding has changed many times, I remember metal window frames being bonded at one point, and I have only a couple of copies of the regulations so even if I wanted I could not check if an earth is required on the lights of a 1965 house, we all know with that one it was 1966 when the rule changed, but I can't produce a copy of the wiring regulations to show in 1965 you don't need an earth.
So it is just as well looking as potential dangerous not does not comply. However although the regulations may say manufacturers instructions should be taken into account not followed blindly, since we in the main have no idea why a boiler manufacturer states it needs to be protected by a type A RCD at 30 mA we have really no option but to note lack of RCD, as to if code C2 or C3 I would agree not cut and dried, but be it solar panels, or electric car charging point today the requirements are getting complex, so the inspector on going around the home seeing an inverter drive washing machine, inverter drive freezer, solar panels and electric car charging point could in theory issue a code C2 even when a 30 mA type AC RCD is fitted.
I think that would be going OTT, but in real terms to be sure nothing which a manufacturer says needs RCD protection is in the home is near impossible, and with lack of bonding or a TT supply clearly a C2, but for rest I would say C3.
Don't get me wrong I think all homes should have RCD protection, what we are doing is looking at the English not what should be done, but with a TN installation with all bonding in place, and no fixed equipment which asks for RCD protection then can't see how it can be a C2.
The Electricity Safety Quality and Continuity Regulations 2002 said:
“consumer’s installation” means the electric lines situated upon the consumer’s side of the supply terminals together with any equipment permanently connected or intended to be permanently connected thereto on that side;
is the problem "intended to be permanently connected" will to my mind include washing machine, tumble drier, freezer, fridge freezer, extractor fans, showers, immersion heater, and central heating boiler. And I think it would be rare that one of those did not say it needs RCD protection.
So I can say not retrospective, which is true, but likely some thing will mean there needs to be RCD protection. I see
701.411.3.3 Additional protection by RCDs
Additional protection shall be provided for all circuits of the location, by the use of one or more RCDs having the characteristics specified in Regulation 415.1.1.
NOTE: See also Regulations 314.1(iv) and 531.2.4 concerning the avoidance of unwanted tripping.
quoted many times however not sure I would want to quote any regulation, as then it makes it look as if following the current regulations as if a new build, and if cured by not fitting a RCD but bonding instead, then there could still be a potential danger due to electric car charging or solar panels.