Tale of tails: how long can a tail be?

[ToughButterCup]

According to our DNO, our meter tails must be no longer than 2 meters. Really?

 

I expect I haven't been asking the right question(s). 2 meters means that the meter must be installed within the heated envelope of our house. It's not that I begrudge the meter its rightful place in the world, but 2 meters? REEaallly?

 

I'm looking to the Collective Wisdom to come up with a stunning plan to allow me tails of about 8 meters: because that's where I (the customer who is nominally King) wants the meter. Why should we keep the DNO's meter nice and warm? 

 

Ian

[Jeremy Harris]

The solution is to run the tails to a fused DP isolator switch and then run a longer length of suitable 25mm² cable to the consumer unit. 

 

In our case we have the fused switch in the meter box, fed directly by the tails from the meter, with an 80A fuse fitted (so that blows under extreme conditions rather than the 100A fuse in the head) and then the house is fed by a run of 25mm² 3 core SWA that's around 15m long, as the CU is upstairs in the services room.  The SWA comes in on the underside of the meter box, via a waterproof gland, and earthed banjo, and at the house end it terminates in a metal adaptable box with another gland and banjo.  There's a Henley inside the adaptable box plus an earth block, with 25mm² tails plus the earth fed to the CU that sits just above it.

[Nickfromwales]

 

This shot shows the head, then the meter, then the DP fused isolator ( KMF ). 16mm2 tails to those. Then 25mm2 tails leave to go to the CU location 13 metres away . 

[ProDave]

The issue is not how long can your tails be, but the DNO will only allow THEIR fuse to protect tails up to 3 metres long. So if you want longer, do as already suggested and fit a KMF with an 80A fuse in it.

[PeterW]

Yep same - only difference is I split to a submain panel in an adjacent box that covers the gates/outdoor lights and then 25mm² 2 core SWA to the house, ducted for the last 5m under the slab.

[ToughButterCup]

1 hour ago, JSHarris said:

[...] a fused DP isolator switch [...]

 

[...]  fed by a run of 25mm² 3 core SWA that's around 15m long, as the CU [...]

waterproof gland, and earthed banjo, and at the house end it terminates in a metal adaptable box with another gland and banjo. 

[...]There's a Henley inside the adaptable box plus an earth block, with 25mm² tails plus the earth fed to the CU that sits just above it.

 

 

DP = Double Pole?

SWA = Steel Wire Armoured?

CU = Consumer Unit?

Waterproof Gland = one of these?

Henley = a connector like this?

 

46 minutes ago, ProDave said:

[...] do as already suggested and fit a KMF with an 80A fuse in it.

 

 

KMF = a fused main switch  -  one of these ?

 

You lads with your lingo.....

 

It's good for me to feel flummoxed by techie terms occasionally. I do it too often myself.

Ian

 

[Jeremy Harris]

The abbreviations are right, sorry for not spelling them out - I should have remembered to spell them out the first time I used them in a post (not a bad bit of guidance for the forum, really, to do this).

 

The waterproof gland for armoured steel wire (SWA) are like these; second lot down are the waterproof (IP66) ones:  https://www.tlc-direct.co.uk/Main_Index/Cable_Accessories_Index/Glands_SWA/index.html

 

The KMF is right, too.

Edited March 14, 2017 by JSHarris

[ToughButterCup]

[Steptoe]

A Henley is actually an ISCO - Insulated Service COnnecter (use single pole ones if you can, not double pole)

A bit like Hoover is actually a vacuum cleaner

SWA glands are CW type as opposed to BW for internal

You shouldn't banjo a CW gland. 

 

Edit to add:

If you are running the tails through a ferrous material all the cables should pass through the same hole.

Edited March 14, 2017 by Steptoe

[joe90]

Glad I read this, my meter is in my garage then like others underground cable to the house and distribution board. I Will need to fit an additional fuse before underground cable.

 

p.s. Do I get a prize for no Abbreviations?

[ProDave]

2 minutes ago, joe90 said:

Glad I read this, my meter is in my garage then like others underground cable to the house and distribution board. I Will need to fit an additional fuse before underground cable.

 

p.s. Do I get a prize for no Abbreviations?

Yes.

 

You need a KMF