Firstly I have stated on here before that I consider it should be a requirement for UK TT systems to have an up front TD RCD so that there is not reliance on a single device. IMO the chance of two RCD's failing is beyond remote.
Secondly I can see the point of going to considerable legnths to get a low Ra on large and complex installs....on the typical small TT install usually discussed on this forum,I cant.
Thirdly I resent my professionalism being called into question when I am at the very least complying with british standards,and in fact exceeding them by advocating the use of more than one RCD.
Surely your not saying/implying that BS 7671 needs it's present standing on TT systems amending?? ....But then again you must be, if you feel the need to have more than just the one RCD on a TTsystem!! So you don't seem to want to trust a 200 ohm Ra and a single RCD either... I've never suggested that one should go to considerable lengths on a domestic installation. What i have tried to put forward is how to gain a better TT Ra value. I certainly dismiss the idea of an electrician whacking in a short thin rod willy nilly and having him call it a TT system, that's just a complete farce!!!
I do not have an attidude that sucks.....I dont try,as you put it,because what you insist is essential is a waste of time.I dont waste my time or my clients money. My point exactly you don't even bother to Try!! So you really don't know if your wasting you time or not!! In this threads case, if the OP has a 20 ohm value from a single rod (assumed single rod) then surely extending that rod isn't going to be a waste of time or money, even if he then extended it to a third rod (3m) as he could well be close to a sub 1 ohm value.... Telling the guy to not even bother trying is well out of order here!!!
Fourthly if you can give an actual instance of an incident on a UK TT system which would have been prevented by a lower Ra then please do so....( I recall you were asked for this on another thread by IQ and failed to come up with anything then).
As i remember, it was about RCDs and if i had any proof of a RCD failure causing a death!! And no i don't, ...but then nor does IQ have proof that it hasn't. Lack of a report isn't in my world, proof of anything!! Unlike some here, ...i'm not surrounded by various forms or papers or reports and statistics, i come on here with nothing in front or around me!! I rely on my education, my knowledge and most of all, my experience...
Going back to what your now asking '' if can give an actual instance of an incident on a UK TT system which would have been prevented by a lower Ra then please do so...'' Again no i can't, ....but then i shouldn't have to, as one would expect their electrician to at the very least, TRY to get a decent Ra if he is installing a TT system on their behalf!!
