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Topic Title: Meter Tails
Topic Summary: XLPE Tails
Created On: 09 February 2013 07:50 AM
Status: Post and Reply
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 09 February 2013 07:50 AM
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statter

Posts: 126
Joined: 06 February 2013

With the price of copper I was wondering why we dont see more use of 90 degree insulation which would allow tails to be 16mm2 rather than 25mm2 ? This would save a third of the copper and have plenty of margin on a 100A fuse for most installations.

I imagine that DNOs / meter companies might query this to start with but I dont see any technical objection. What am I missing?
 09 February 2013 08:39 AM
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Jaymack

Posts: 4639
Joined: 07 April 2004

Originally posted by: statter
With the price of copper I was wondering why we dont see more use of 90 degree insulation which would allow tails to be 16mm2 rather than 25mm2 ? This would save a third of the copper and have plenty of margin on a 100A fuse for most installations.

Velkommen to a virgin poster! The sharp bend for "90 degree" wouldn't be so kosher!

Seriously though, the equipment would also require a rating of 90°C

I imagine that DNOs / meter companies might query this to start with but I dont see any technical objection. What am I missing?

Sorry, couldn't resist - experience?

Regards
 09 February 2013 09:02 AM
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broadgage

Posts: 1293
Joined: 07 August 2007

I dont like the idea of running cables at 90 degrees in an uncontrolled domestic enviroment due to the risks of overheating if articles are stored against them, as is often the case,or if someone later encloses them.

And how hot would they get at 140 amps which the cut out fuse will pass for hours.
 09 February 2013 09:55 AM
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alancapon

Posts: 5766
Joined: 27 December 2005

Originally posted by: statter
. . . I imagine that DNOs / meter companies might query this to start with but I dont see any technical objection. What am I missing?

As Jaymack has already said, finding a CU rated for 90° would be interesting, plus you would not be able to have T&Es touching the tails, which could also be a challenge. Finally, as the DNO's fuse is protecting the tails from the meter to your CU (unless you have long tails, in which case it is to your overcurrent protection), they have a say in their size and construction.

Regards,

Alan.
 09 February 2013 11:30 AM
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UKPN

Posts: 510
Joined: 17 January 2012

more importantly, the meter connection.

Regards
 10 February 2013 09:06 AM
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statter

Posts: 126
Joined: 06 February 2013

..... looks like a can of worms - probably why its not done. I haven't got a copy of the relevant BSs so cant see the temperature limitations on the individual MCBs, Isolators etc ditto for the meter.

I imagine a sustained 140A would destroy most 100A rated consumer units even with 25mm2 tails.

Thanks for the responses.
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