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ARE WE THE MEAT IN THE SANDWICH?

John Peckham
I know I am old grumpy and cynical as my wife tells me that every day! 


However am I right in thinking that BS 7671 and LV installation design requirements are having to compensate for problems in the DNO supplies to building and at the other end poor quality appliances. It appears to me we are having to compensate for other people's failings.


For example having to compensate for DNOs not maintaining their supplies in good working order, I am thinking hear about PEN failures, although their is a statutory duty (ESQCR) to do so. At the other end poor quality appliances susceptible  to transients, counterfieght goods from the Far East and generally not fit for purpose e.g a certain make of fridge freezers, washing machines and tumble driers.


Surely us LV piggy in the middle has become the meat in the sandwich?


Discuss? 


JP


PS where has the smell checker function gone on this forum?
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  • 0
    The purpose of regulations and standards is not to sell new products to customers, by forcing new products which they do not need onto them. That is exactly what is happening with surge protection and AFDDs. It happened with PME too, because it was supposedly cheaper and the saving would be given to the customer. Now the poor network condition is being used to force the customer to take precautions because of the network problems.


    The problem we are having is very simple: All these "nice to have" products are put into BS7671 as requirements, and due to other factors we must implement then in all new installations whether the customer wants or can afford them or not. A secondary problem is that the prices being charged are simply rip-off, an AFDD probably costs a few quid to manufacture (and sells relatively reasonably in the USA, say £20) yet here is ten times the price. It may be claimed that this is development cost, but very little is required to simply reproduce the American product, and there is little reason to start from square one anyway. The same applies to surge protectors, they are simple, have been available in all sizes for a long time, and are overpriced and not designed to fail cleanly so need external bits and pieces.


    The next point is that neither of these products has any pedigree, although AFDDs have been in the USA "Code" for at least 10 years. Our own tests show that AFDDs are not good at detecting ANY known real faults, although they can be induced to trip with a test jig which has little comparison to reality. To get an arc, a material (Carbon) which we do not use in installations has to be used as one of the electrodes, as otherwise, it is virtually impossible to strike an arc between copper electrodes. The second point is that an AFDD does nothing with an RCD protected T&E cable because any fault will trip the RCD long before the AFDD, and domestics have RCDs everywhere! I have covered surge protection elsewhere, the susceptibility of electronics is basically bad design, good electronics is very robust indeed.


    Overall it is doubtful that we need either of these products, in a free market they would fail very quickly.
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  • 0
    The purpose of regulations and standards is not to sell new products to customers, by forcing new products which they do not need onto them. That is exactly what is happening with surge protection and AFDDs. It happened with PME too, because it was supposedly cheaper and the saving would be given to the customer. Now the poor network condition is being used to force the customer to take precautions because of the network problems.


    The problem we are having is very simple: All these "nice to have" products are put into BS7671 as requirements, and due to other factors we must implement then in all new installations whether the customer wants or can afford them or not. A secondary problem is that the prices being charged are simply rip-off, an AFDD probably costs a few quid to manufacture (and sells relatively reasonably in the USA, say £20) yet here is ten times the price. It may be claimed that this is development cost, but very little is required to simply reproduce the American product, and there is little reason to start from square one anyway. The same applies to surge protectors, they are simple, have been available in all sizes for a long time, and are overpriced and not designed to fail cleanly so need external bits and pieces.


    The next point is that neither of these products has any pedigree, although AFDDs have been in the USA "Code" for at least 10 years. Our own tests show that AFDDs are not good at detecting ANY known real faults, although they can be induced to trip with a test jig which has little comparison to reality. To get an arc, a material (Carbon) which we do not use in installations has to be used as one of the electrodes, as otherwise, it is virtually impossible to strike an arc between copper electrodes. The second point is that an AFDD does nothing with an RCD protected T&E cable because any fault will trip the RCD long before the AFDD, and domestics have RCDs everywhere! I have covered surge protection elsewhere, the susceptibility of electronics is basically bad design, good electronics is very robust indeed.


    Overall it is doubtful that we need either of these products, in a free market they would fail very quickly.
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