There seems to be a repeating mantra throughout the youtube presentation which becomes irksome if you listen for long enough. It seems that we just adopt, or rather 'harmonize' without question and then defer the responsibility for decision making back to CENELEC rather than think it through and act for ourselves.
How is it that we allow the tail to wag the dog? Isn't it time that we departed from harmonization and went our own way?
Comments welcome
Graham, why would it be remiss of us not to give consideration to bad science? Why should we slavishly adopt something which is of dubious merit? You keep returning to the RCD analogy - it smacks of obfuscation - the science behind RCDs and their ensuing benefits is clear. The 'science', or rather 'pseudo-science' behind the reasoning which has pushed the mandating of the installation of afdds not so much.
Indeed! This is a bad analogy, with a completely different risk profile. Unlike a house fire, the consequences of a fire at 30'000ft means that you cannot just walk out of the front door to escape, Same with any fire at sea, whether it be a submerged vessel or a surface one.
Over the last 20 years or so, I have had great success running a succession of 2nd hand cats acqured from the blue cross, typically for the last 5-8 years of their lives, when original owners can no longer look after them for one or other reason, and they all come with paperwork that verifies they are fully functional apart from the procreation features.
Once expired they can be buried in the garden with due ceremony, some tears and a little straw, where they will decompose. I have yet to bother to check and see if I am supposed to register this with any higher authority.
None as far as I know has been CE marked anywhere, although they have all been 'chipped', allowing me to program the cat flaps to match and keep both wild and neighbours animals out. So far however we have not had any mice in the house not any arc initiated fires we were not expecting, (*) so despite the lack of a CE mark they must be doing some good.
Mike.
(*) that choice of wording is deliberate
Most is MIL spec and that is quite variable (MIL-C-27500). See e.g. https://www.ryanelectronics.com/products/m27500-wire-specification-breakdown/
The issue is the insulation and its properties. An aromatic polymide known as Kapton was commonly used up to and beyond the 1990's (for a list of aircraft which used it, see https://www.interconnect-wiring.com/blog/aircraft-kaptontm-insulated-wire/ I don't know whether the list is complete). With age,iIt tends to build carbon conductive stripes on the inside, presumably with some release of hydrogen, and then when it gets cracked an arc through the crack explodes the wire. There are some FAA videos from the 1990's showing this (I can't put my finger on one at the moment).
I can't claim to be expert on the signals generated in chewed cables but I'd have thought B suffices. If it's any better than A ..... I don't have stats, and I don't think the ZVEI has them (the electrician's professional society in Germany).
As for the cat, done. But in a competition between a cat and a marten, I would favour the marten. My neighbour on the one side had at one point three cats (one wild) and a marten. The local marten is with the neighbours on my other side (at least, the one I've seen).
have you tried testing an AFCI for anything other than it's RCD function ? The real bone of contention is that they are not demonstrated to do any good.
Nope, I haven't. I will buy the observation that alu+Kapton is a different kettle of fish than copper(+whatever).
However, when I ran the standards group performing a risk analysis for the process of charging electric vehicles for the German electrotechnical standards organisation, there were a number of highly-regarded wiring experts (such as people from Mennekes who designed the Type 2 plug which is standard in Europe). They were quite insistent on Type B RCDs, especially for public charging stations and free-standing boxes with unconstrained runs of cable, because of the potential for physical abuse, including by critturs (a charging cable does have somewhat of an all-you-can-eat aspect about it). I deferred to them then and would do so now. But of course that is no technical argument to counter yours.
And a type B for a charging system that puts DC signals on the CPC and a test loop as a cable plugged in detection, and does so always, by design, is a very good idea. Unless there are other measures to avoid escaping DC from blinding a normal RCD, it is actually possible single fault.. That is not the same as any 'normal' domestic load, where there is no DC signalling used to decide if it is safe to power the cable up or not.
Mike.
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