Since BS 7671 is not law but can be used in a court of law, hard to say any regulation has to be legally followed, specially since it says in the intro to BS7671 that wiring complying to a previous edition is not necessary dangerous.
The main problem with RCD's is the changes in 2008 allowing reduced bonding if RCD's are used. So we can find where bonding has been removed, but the RCD has not been fitted.
The other problem is where a rule has been clarified, and it has been pointed out, how people have been interpreting the rules wrong. I have never heard of an electrician returning to change an installation when he realises he has made an error reading the rule book, I am sure there are some, but very few.
As to how far back one can go, not sure, reading 13th edition, it would seem not having an earth to a ceiling light was permitted, but not a wall light, as to not fit the earth they had to be "mounted at such a height that they cannot readily be touched and are out of reach of earthed metal." Now my parent's house, had wall lights without an earth, but can't really ask the builder to correct something done in 1956.
I consider an EICR should be done every 10 years, so after 10 years faults should have been highlighted. But every installation shall be divided into circuits, but does a RCD form a circuit? An assembly of electrical equipment supplied from the same origin and protected against overcurrent by the same protective device(s). Well it the current goes over a set amount to earth, the RCD trips, so I would say it is an overcurrent device.
So (iii) take account of danger that may arise from the failure of a single circuit such as a lighting circuit
(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced
by equipment in normal operation, both question the whole idea of having only 2 RCD's and has done since 2008, this is not a new rule, use of emergency torches can remove the danger, but the normal operation means no more than 9 mA (30%) leakage with a 30 mA RCD, since equipment can have a 3.5 mA leakage, after which a plug and socket is not allowed, to put lights on same RCD as sockets, or to have multi socket circuits on the same RCD, would seem not to comply since 2008.
So are we returning to swap twin RCD consumer units for all RCBO, well we are not without being paid to do it, even if it seems it never did comply.
However, with a caravan we have one RCD for all, and no real way around it, so if we can do it with a caravan why not with a house? Well some caravans do have 12 volt lighting, and gas cooking, so not relying on 230 volts, and the same applies by fitting some emergency torches, so is that all we need to do?
When I had a RCBO trip, which would not simply reset, I was thankful to having all RCBO's I could leave it until morning to sort out, and the homeowner can select what he wants, I have an UPS for central heating and freezers, it is my call, what I have.
Where the problem arises is with rental accommodation, is it acceptable to call the letting agent if a RCD trips? I was surprised that a plumber had to attend to adjust the ball cock in a toilet, it is something I would do without thinking about it, so fit all RCBO's and likely if there is a problem, it is not considered as an emergency, but only two RCD's and the landlord has call out fees.
I can see arguments both ways, so where do we draw the line?
