"17 edition"consumer units still being sold.

Andy, why are you picking on TT installations? Have you a statistic that says that they cause deaths, and in how many cases is this due to RCD failure and how many due to some fault which you have yet to describe? Setting up a straw man is a common way used by troublemakers and charletons to show that the straw man is a problem, whereas such is not required if a real problem is identified. It is common in USA politics. I would be most interested to see the data, which is always missing with such arguments. I was not specifically talking about TT, just any installation, it is true that there could be special problems with certain faults on TT systems, which have never been as robust as TN-S or properly working TNC-S.


Moving on to other ground, I do not really see why there is a significant difference between a type A and B in price, except that quantities may be smaller for Bs. They are undoubtedly electronic (as is the type AC I was testing recently) but this is not really a difference affecting price much. Volume electronics is very cheap to manufacture, the price paid is hardly related to the costs, for example Apple products and the cash mountain. The design of a DC sensitive RCD is not difficult anyway, although it probably would not have a transformer, just some precision electronics, perhaps some Hall sensors and coreless coils. The chip to do this would cost perhaps 20p in million quantities, and you could have it in less than a year. Seeing the problems smart meters have had, it is fairly obvious that the industry involved does not have the Engineers or technology available for such development work in what they consider an alien area. Certainly until they have the right product at the right price we should not change BS7671, there is no data that it is necessary or economic. I can just see all those EICRs saying code 1 for "the wrong type" of RCDs, based on the same "what if" statements unsupported by evidence.

Andy, why are you picking on TT installations? Have you a statistic that says that they cause deaths, and in how many cases is this due to RCD failure and how many due to some fault which you have yet to describe? Setting up a straw man is a common way used by troublemakers and charletons to show that the straw man is a problem, whereas such is not required if a real problem is identified. It is common in USA politics. I would be most interested to see the data, which is always missing with such arguments. I was not specifically talking about TT, just any installation, it is true that there could be special problems with certain faults on TT systems, which have never been as robust as TN-S or properly working TNC-S.


Moving on to other ground, I do not really see why there is a significant difference between a type A and B in price, except that quantities may be smaller for Bs. They are undoubtedly electronic (as is the type AC I was testing recently) but this is not really a difference affecting price much. Volume electronics is very cheap to manufacture, the price paid is hardly related to the costs, for example Apple products and the cash mountain. The design of a DC sensitive RCD is not difficult anyway, although it probably would not have a transformer, just some precision electronics, perhaps some Hall sensors and coreless coils. The chip to do this would cost perhaps 20p in million quantities, and you could have it in less than a year. Seeing the problems smart meters have had, it is fairly obvious that the industry involved does not have the Engineers or technology available for such development work in what they consider an alien area. Certainly until they have the right product at the right price we should not change BS7671, there is no data that it is necessary or economic. I can just see all those EICRs saying code 1 for "the wrong type" of RCDs, based on the same "what if" statements unsupported by evidence.