Flexible 'tails'

It sounds like the ones they are taking out are the ones that aren't your responsibility anyway.  I assume that they haven't established that the terminals in the cut out or in the meter are rated for the use of flexible tails.

If there's an isolator, then the tails from that to the consumer unit are your responsibility to terminate correctly.

Is this with or without crimps? ;-)

If the replacements are rigid, how do they fit them?

By referring to 'flexible' you do realise I'm referring to 19 strand as opposed to 7 strand cable.

I presume the "flexible" ones are 19-strand vs the traditional 7-strand ones.

While the 19-stand ones are easier to use and most likely fit more reliably into cage-clamp terminals found in most CUs these days, they don't necessarily do as well in the twin screw tunnel terminals (still usual on the DNO/meter side of things)- as the thinner strands are more likely to escape the screws. Ferruling in theory should help, but that in a way makes it a single strand - which the terminals probably haven't been tested for either.

   - Andy.

I don't know what the difference in overall diameter is between the two variants but the 19 strand definitely fills the barrel on a 100A credit meter, there's no way the terminal screws are going to squirrel their way past the strands. As for fitting ferrules, you'll never get one to fit in the barrel both types of cable are a snug fit in a 100A meter.

I wonder if Eon are worried about a stray whisker short circuit problem, either real or imagined.

Certainly in other parts of the world such cables do get used in all sorts of terminals with no significant issues at all when competently installed.  For cage clamp terminals and things that don't appreciate the tail wagging the dog, its actually better.

Equally a well ventilated 16mm cable works on a 100A fuse as well, with no issues, but it does not stop folk in the UK  insisting on changing to 25mm, then finding it a tight fit ;-) We are not always in step with the rest...

It may be as simple as 'not what our instructions said' and very little thought beyond that.

Mike.

1 strand out of 19 hardly counts as a whisker in my world. I did ask the e.on chappy what was the reason given for the removal but he didn't know only that they'd been instructed to do so.

1 strand out of 19 hardly counts as a whisker in my world. 

Agree, its pretty noticeable in this cable type in my world too, but maybe the risk assessors are thinking of the problems you sometimes get with stranded cables in smaller sizes, and imagining that it scales, when really it does not.

M.

Well, I did wonder, but perhaps better terms would be, "stranded" and, "fine stranded" or even, "extra fine stranded". Please forgive me for failing to give a reference, but IIRC, they are in BS 7671 somewhere.

grahamro said:

I'll keep using flexible 'tails' untiil I'm told oficially a reason not to

To be clear, whilst often advertised as such, e.g. https://www.cef.co.uk/catalogue/products/4626461-25mm-flexible-double-insulated-meter-tail-pack-1m, 19-strand tails are in fact Class 2 stranded circular conductors. BS EN 60228 only specifies the minimum number of strands for Class 2 conductors, being 7 for 25 sq mm and 35 sq mm csa. Whilst for Class 5 flexible conductors BS EN 60228 specifies only a maximum diameter of wires, this would lead to a minimum of around 190 strands for 25 sq mm csa and 266 strands for 35 sq mm csa.

What's the issue, can they be used without special preparation?

Well, that depends on what the terminal manufacturer has designed and tested for ... if it's the minimum in a standard, perhaps not.