[assuming you are talking about my immersion CU, and that the question is real rather than rhetorical!] ... the present day 'domestic usual' - i.e. 6kA, and there are two of them (and nothing else). They cannot, of course protect against faults arising in the cable we have been discussing, since they are downstream of that cable.
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Right; we're on the same page, then!
Indeed, hopefully the PEFC would not be greater than the breaking capacity of the MCBs, but that's hardly a sound (or compliant!) basis for design, is it?
In terms of regaining wallspace, would there be any reason not to use DIN rail mounted fuseholders & switches in a suitable enclosure ?
I wouldn't call it selfish - rather, very reasonable and commercially sensible, and if I saw the situation as "the DNO supplying equipment to protect customer wiring" then I would be saying exactly the same as you. However, I'm not suggesting that the DNO should supply anything that they don't have to supply for their own reasons (their fuse) and nor am I suggesting that they should be expected to take responsibility for anything that happens downstream of their meter.
The argument I'm putting forward is essentially independent of the length of the tails, so theoretically requires no limit. The more I think about this, the more I suspect that (as you have hinted) this may be more about lawyers and litigation than engineering sense. It's probably not helped by confusion (certainly on the part of much of the public, and possibly also the law) as to the ownership of the meter tails. Except in the minority of cases in which the DNO supplies a meter with a built in isolator, the fact that the DNO seals the connection at one end might strengthen the feeling (perhaps even in law) that they are the property (and responsibility) of the DNO. However, even given that, I wouldn't have thought that it would be beyond the capabilities of lawyers to produce contracts (and if necessary support them in Courts) which made it very clear that, provided only that they provided an electricity supply which 'did what it said on the tin', the DNO was responsible for nothing beyond their meter.
Thanks for your interest and suggestion. You presumably don't mean 6A - did you mean to type 60A?
I have several of the big MEM switch-fuses, which have probably been in service for about 30 years. They are appear visually to be in perfect condition and never show any signs of any warmth at all - the only problem is their size.
63A actually - no I didn't really mean 6A
This one was faulty - and burning up
I think someone applied my IR thermometer to it and got some frightening reading. Once the contacts get hot enough, they lose their spring and the problem gets worse - the smell was gave it away.Fair enough, but that is just an 'internal' matter caused by Balkanisation of the electrical supply process, and is of no real concern to the customer, who is merely concerned about where his/her 'ownership' and responsibility starts, regardless of who (one organisation or many) bear responsible for the rest!
Yes, I can imagine that, in reality, it could easily produce more problems than it solves - but it might help people and, in particular courts, to understand who 'owns' (and is responsible for) the tails. If I bought, and became owner of, a hosepipe, but the supplier padlocked one end of it to my front gate, so that I was not free to do with it as I wished, a court might well question the extent to which I had become the 'owner' - maybe a bit like owning a Leasehold!
'You' (the DNO) shouldn't really feel uncomfortable since, as you keep saying, that cable is the problem/responsibility of the consumer, not the DNO.
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