I think the RCD has moved on. I have posted
this link before and it details how the modern RCD is able to hold in with spikes.
There is also the auto resetting RCD
which although expensive does address the problems of unattended and other situations where the occupants can't re-set the RCD.
The problem with losing clocks and recording information has also been redressed and my Sky box of course can't record when there is no power but it does remember what was programmed in and will still auto record on next event.
Using cheap and/or old technology equipment there is a problem. But over last 10 years I think every alarm clock has battery back-up.
The problem as I see it is 314.1 Every installation shall be divided into circuits, as necessary, to:
(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced
It is very easy to write the regulation but in real terms as electricians we have no idea of what the house holder will plug in. So we consider that two RCD's will allow a 15ma leakage on each circuit which we consider ample. Then we find the house full of IT equipment and each item is leaking just a little bit so the trips are right on the edge.
In a commercial situation we change the RCD for an Isolator and fit RCBO's it costs maybe £100 but that is nothing in the grand scheme of things. No Part P to worry about we just get on and do it.
However in the Domestic even though the occupant is working from home and doing exactly the same as in the commercial situation there are two extra problems.
1) The work is paid for out of a private guys pocket who is not gaining from the money he has to pay out.
2) The LABC want their cut from the work done so that £100 becomes £200 for exactly the same job.
So in the domestic the occupier is looking to move the blame and cost of up-grade. He reads that the regulations say it should be designed not to trip and wants the electrician to return and correct it FOC.
So if an electrician has fitted just one RCD to cover whole house we would say fair enough he should have fitted two. But when two are fitted who's fault is it that it is tripping? Even with one RCD in a flat no bigger than a caravan should we really be blaming the designer who did the job with hands tied behind his back not having a clue what equipment will be installed?
As to heating controls again likely battery is dead or very old. I have needed to renew batteries in the past in both heating controls and intruder alarms in both cases the owner seems to think they will last for ever.
