Have read a previous trail on RDS tripping but electrical storms were not mentioned. My house is rural with an overhead mains supply. There is one 100mA RCD plus eight MCB. Whenever we are away (or at home) the RCD will trip if there is a nearby thunderstorm. Just our house, not a general power outage. If we are on holiday, freezer and heating system stops so are at risk for poisonous food and/or frozen house pipes.
You obviously didn't read the right one, since in at least one of them I reported (again, rural with overhead supply) that I used to have RCDs tripping all over the place whenever there was lightning anywhere near my home. However, that all seemed to stop a few years back, and the only explanation I can think of is that they must have found a wave of improving the 'filtering out' of lightning-induced spikes on their network
Is it a) Possible to fit a much less sensitive RCD or ...
A
different RCD might, by chance, be less sensitive to lightning, but one which was 'less sensitive' by design would not be acceptable (would not do its job). The RCD you have is already not sensitive enough to provide protection to persons against electric shock.
b) get an electrician to fit a bypass of the RCD circuit to be activated when we are away. Legal? The 8 MCB could continue with short circuit protection? ... My understanding is that the RCD is to prevent human electrocution, so this would not matter when the house is empty (ignoring a possible burglar human rights issue?)
It would certainly be unwise, almost certainly non-compliant with regulations under any circumstances, and certainly non-compliant (and dangerous) if, as seems probably the case, you have 'TT' earthing - apart from anything else there would always be the danger that you could easily forget to remove the 'bypass' when the house was occupied.
As for the purpose/function of the RCD, one purpose is, as you say, to reduce the risk of certain types of electric shock being fatal - so, as you imply, only relevant when the house is occupied. However, the 100mA RCD you have (presumably because you have a 'TT' earthing system) is not adequate for that purpose - to protect persons you would require more sensitive (30mA) one(s). In addition, if, as seems likely (from the fact that you have a 100mA RCD) your house has a "TT" earthing system (i.e. you have your own earth rod), then the RCD is essential to provide protection against 'live-earth' faults/shorts (which could cause fires, even when house was unoccupied), since MCBs are not usually capable of providing such protection in TT installations.
If you do have a TT installation, it's hard to think of a solution (other than trying a different RCD, just in case it is less sensitive to lightning, or maybe some sort of 'surge/spike protector. but I'm not convinced that necessarily would solve your problem). If it weren't TT, then you could discuss with your electrician the possibility of running crucial things (e.g. freezer, heating controls) off dedicated non-RCD-protected circuits.
Kind Regards, John
in order for it to operate.
