The £1300 AFDD consumer unit

For example, how does the price of a basic CU compare with a window? Yes, just one window.


A typical 4ft by 4ft with fanlight and casement, with locking handles is perhaps 150- 200 ex works. We are no longer talking single glazing and putty for dwellings, that would still be still cheap, but infra-red reflecting coatings and inert gas filling are rather more  complex to organise.


And against this, how long does it last ? - at this rate of regs changes we'll be lucky if the consumer unit  lasts 10 or 20 years. Nearly all windows have a guarantee of at least 10 years, and well made ones may be twice that, and to be honest we'd be very suprised  if it did not last for 30, and replacement glazing units are very much still available in pretty much all sizes ever made


Also there is considerably more raw material in a window. Do not be fooled by apparent complexity of the CU, electronics can be assembled un-touched by human hand, and injection moulded plastics are pennies, once the moulds are made at perhaps 100K for hard tooling - so making a lot of the same is the most cost effective way.

 I agree that the expectation of a £50 quid CU is unrealistic, but I think expecting folk to fork out hundreds for an update that adds little to the house safety is also misplaced, and folk will keep the old stuff going for longer. There are plenty of BS3036 hot wire fuses still giving good service, and some still will be in 2040 at this rate.

M

Mike

It comes down to who owns the patents and how much they are going to charge for licences; and if they are prepared to let anyone else have access to their designs.

I don't have any qualms about fitting AFDD-free consumer units because I don't believe they offer anything by the way of life-saving enhancement - unlike a RCD/RCBO..


They are just bells and whistles for those who can afford to pay the extra.. To use a car analogy, the Standard L model V's the Ghia option. One comes with everything you need to drive safely, but the more expensive one gets you a posh interior and built-in radio. Nice to have, but the radio won't make your car any safer than one without..

Patents Sparkingchip? There is nothing to patent in any of these items, the designs have been around for far too long. All these things are quite cheap to manufacture as Mike says. Do you have any idea of the cost of the parts of even a high-tech item like the latest iPhone is? Probably about the same as a simple CU retail. The margins on the phones etc. are huge, as you can see from the cash piles of companies like Intel and Apple. I can buy a cheap double glazed window 1m square from a trade supplier for £40-50, not the finest and standard sizes only but I would still expect 50 years life. The Wooden windows in my house were generally fine90 years old, just a huge job to paint, so I had them changed for very expensive Everest ones, which are nothing like as good as they used to be. They have all the features like low emissivity glass and very good locks, Argon in the double glazing etc. but still, the only real change is that they don't need painting!


I suggest that an RCBO cost less than £2 ex. factory (in China), if I buy a sensible quantity perhaps 500k. There is nothing in there which costs very much. An AFDD contains a computer, well in volume these cost 25p! The surge protection VDRs are also cheap, you cannot look at the price of one-off and say it should be half, in volume, it is more like 10% or less.


However, my own objections are largely technical and performance related, as I am sure you will have gathered. If one could say "this device which costs this much, will prevent you from having ANY fires", then I would be on firm ground and the consumer could choose, of course, backed by a guarantee (which would cost little if the performance could be proved). However, we are now in the land of untestable performance and wild claims which can easily be disproved by experiment, and mandates in installation regulations. This is a crazy situation. We have lightning protection which might work, but not if the spike is bigger than a minor disturbance, with a seriously reactive method of earthing, working against a very low impedance source (the mains supply), which means that spike clipping will be marginal at best. In a real installation, it is unlikely that any of these devices could clip an 8/20 spike (the test standard) with a current of a couple of kA and limit the voltage to 4kV, because of the connection inductance and earth resistance. This is a peak power of 8MJ, roughly the same kinetic energy as a car has moving at 100 m/sec stopping dead. Not a lot left of that! Perhaps I am being unfair and these lightning spikes are much smaller and of much less energy, in which case why do I need these devices? The LV directive says that electronics must withstand 4kV low energy spikes, so what am I protecting, perhaps slightly bigger spikes but not much bigger! The incidence of such is not clear or documented, just some arbitrary amount of LV line above ground depending on the area living density. This seems to be aimed at induced current from nearby ground strikes, but have you ever had one near you? Again only high exposed trees usually suffer, and there are few of these in Lincolnshire although there are a lot of overhead lines, so a lot of surge protection.

Whilst in some cases surge protection may be useful Graham, the regulations take this to being a requirement and specifically state that this is lightning protection. The specification for its fitting is entirely based on lightning strikes. Were your devices suffering from such spikes or other causes? I know and have measured many mains spikes, but the cause is usually other things, so why not come clean and simply say surge protection may be useful in some circumstances? The cost-benefit analysis should be up to the consumer, not some remote manufacturer or regulation committee who have no idea of the likelihood or cost of any damage. It might well be a good idea for a data centre, but for Mrs Bloggs who has two LED lights, probably not worthwhile. The energy from switching spikes and similar is very low compared with lightning, and may often be entirely satisfactorily removed with very simple and cheap VDRs. Live conductor to Earth protection is rather different to L-N protection, simpler and effective for preventing damage to connected semiconductors, particularly in with the mains supply impedance being raised with some small series inductors, except in extreme cases. The regulations seem to have a fascination with the line-Earth voltage which is only seen by any attached EMC suppression components. I don't doubt that some equipment is occasionally damaged, or at least fails, but deciding the exact cause is often very difficult.

I was still on AFDD, those are covered by patents aren’t they?

An internet search for “AFDD patent” throws up lots of hits.


Such as:

https://new.siemens.com/global/en/products/energy/low-voltage/components/sentron-protection-devices/arc-fault-detection-devices.html

Try this Andy

They have tried to patent a whole variety of things, most of which are simply to try and stop anyone else with ideas. This is common for big companies because they have unlimited budgets. Having been on the other end of this, I would like to see a requirement for patents to have to be shown practical in implementation by demonstration. That is quite a high barrier for inventors, but the whole process is very unfair to small companies anyway.

https://worldwide.espacenet.com/patent/search/family/056092923/publication/US2020326365A1?q=Siemens%20Arc%20fault%20detection%20device&queryLang=en%3Ade%3Afr