Meter tails

[jas0n]

Hi,

 recently I had installed a 25mm swa of a 80amp isolation switch which was terminated into an adaptable box then into a Henley block. 

Of my Henley block I was going to be distributing to 2 cu's. At the moment I was going to use 25mm tails but after thinking about this I was wondering would there be an issue with using 16mm tails?

 

[ProDave]

Hi,

 recently I had installed a 25mm swa of a 80amp isolation switch which was terminated into an adaptable box then into a Henley block.

Of my Henley block I was going to be distributing to 2 cu's. At the moment I was going to use 25mm tails but after thinking about this I was wondering would there be an issue with using 16mm tails?

What do the tables in the regs say about current carrying capacity of 16mm singles in free air (clipped direct)? looks okay to me with 80A ocpd.
 

 

[Evans Electric]

16mm in free air  , as Dave says , and now me too , sounds good .

Do you not have any current rating tables ,?  Sorry but I had to ask. 

 

[Rob_the_rich]

16mm armoured clipped direct looks ok to me instead of the 25mm you have used, but you may have used a different reference method.

 

[Blue Duck]

I thought it was against the law to use 16mm tails, despite the load?

:tongue in cheek

 

[Tony S]

 

[Evans Electric]

I thought it was against the law to use 16mm tails, despite the load?

:tongue in cheek

Well Ducky , a mate of mine was arrested by the Electric Police for using 16mm tails, a plumber shopped him I believe ...he,s serving 5 years in The Green , in solitary in a section they laughingly call  The Faraday Cage. !!    :innocent

In fairness   I believe we were once told to only supply  25mm tails to meters as the , then,  Electricity Boards would only accept 25mm so they could begin a programme of fitting 100A fuses  .    But yes you have to present 25mm tails for connection to the meter. 

Now they seem to be reducing the size of their fuses. 

I think what we do as contractors  on the 7671 side is up to us .

Some years back, the , then , Electricity Board , insisted I  change the tails to a two way Wylex board  to 25mm  or they'd walk off the job.    You can't actually fit 25mm into those things  so it was back to the old days of snipping half the cores out of the 25mms  to keep them happy.  

 

[OnOff]

I've been in after BG had been in to fit a smart meter. They fitted the smart meter along with a Wylex REC2 inc all new 25mm2 "their" side - no charge to the customer. Left telling the customer they best get THEIR cloth / rubber covered 16mm2 tails upgraded. You'd have thought coming in and going to all that trouble they would have done it as part of the service for about half a meter of brown & blue 25mm2.....but NO.

 

[Andy™]

easier to stick the old tails into a REC2 than open the CU and change the tails to there

 

[Blue Duck]

Probably not allowed to touch the CU incase it spontaneously goes up in flames??? Also in their interest to anything that may make them more money down the line and not do anything else.

I've worked on flats with 10mm pyro supplies I told another ''electrician'' and they went nuts at me; 10mm WTGrape? you'll burn the place down yada yada yada, turns out they had never heard of pyro before....

How long will a 60a fuse run at 100a for ??? :innocent

headbang

 

[Evans Electric]

Yes  AND  10mm Pyro is equal to 16mm  PVC  in current carrying terms. 

 

[Rob_the_rich]

How long will a 60a fuse run at 100a for ??? :innocent

just over 3000 seconds (50 mins) for a BS 1361, according to big red book. I don't think they are tested for much longer than that, the lines don't continue for some reason. Extrapolating gives me 5000 seconds (83 mins)

(A 45A one will last ~1200 seconds (20 minutes))

Hope this answers your question to your satisfaction

Have a nice evening.

 

[kerching]

How long will a 60a fuse run at 100a for ??? :innocent

headbang

Mr Merlot reliably informs me that this is in the region of 58.3 minutes ish or  thereabouts

 

[andy_spark]

 On a dairy farm I had to change an 80A fuse in fused isolator switch which had blown due to over load.  it was so hot I had to use a tea towel to remove it form the holder.  I estimated after that it had been drawing at least 145 amps for more than an hour. The cause was a temperature of about -14 degrees and every fan heater they owned switched on to stop the milk pumps from freezing, thawing out tractors and water troughs etc. plus the usual milk pumps, milk coolers, immersion heaters, lots of lighting and so on.

 

[Rob_the_rich]

brb time curve says 80A bs1361 @145A is 2000 secs, 33minutes so it did well to last that long, or not depending how you look at it.