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Topic Title: Consumer unit more than 3 meters from fuse head and meter
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Created On: 21 January 2019 07:40 PM
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 21 January 2019 07:40 PM
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IronFreely

Posts: 445
Joined: 06 November 2014

Just a quick bit of advice please...

I've come across a new build where the developer has installed the consumer unit about 10 meters away from the meter, the meter is outside in one of those cabinets they use and the consumer unit is quite a long way inside in the boiler cupboard... there is a distributors double pole isolation switch but no overcurrent protection other than the main fuse head which is 100A.

I've alwsys been under the impression that when doing this a fused double pole switch or Stype RCD should be used to protect the tails?

Going on, the tails seem to be singularly insulated and only 16mm2. They're also run through a wall cavity and seemingly above a plasterboard ceiling before appearing in the middle of the house...

The developer has told the householder to refer to installation certificates as a means of proving its compliant, I'm pretty sure it's not but I'm open to being corrected.

A handy BS7671 regulation number will certainly help the householder out.

Edited: 21 January 2019 at 07:47 PM by IronFreely
 21 January 2019 07:46 PM
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perspicacious

Posts: 8055
Joined: 18 April 2006

Sounds like a job for JP......

Regards

BOD
 21 January 2019 08:04 PM
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mikejumper

Posts: 2810
Joined: 14 December 2006

Originally posted by: IronFreely
I've alwsys been under the impression that when doing this a fused double pole switch or Stype RCD should be used to protect the tails?

Well I think you've always been under the right impression then.

I think it probably comes under DNO regs. rather than BS7671.

Not good.
 21 January 2019 08:14 PM
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IronFreely

Posts: 445
Joined: 06 November 2014

Surely under BS7671 as everything after the isolator is the responsibility of the owner not the DNO
 21 January 2019 08:14 PM
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perspicacious

Posts: 8055
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help the householder out

Does the householder's certificate carry a logo of one of the schemes and does that scheme operate a robust complaints procedure?

Regards

BOD
 21 January 2019 08:31 PM
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mikejumper

Posts: 2810
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Originally posted by: IronFreely
Surely under BS7671 as everything after the isolator is the responsibility of the owner not the DNO

I was thinking of the rules governing the length that tails can be if not protected by a switchfuse. As far as I'm aware that's a DNO decision, not a BS7671 reg.
 21 January 2019 08:43 PM
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Cremeegg

Posts: 711
Joined: 13 July 2007

Originally posted by: perspicacious


Does the householder's certificate carry a logo of one of the schemes and does that scheme operate a robust complaints procedure?

Regards

BOD



Having tried to pursue complaints against contractors who are registered with the biggest scheme in my experience it is a complete waste of time - they just don't want to know unless its something simple like mis-use of their logo.

Whether the DNO would be interested in an installer breaching their guideline 2 or 3 metre rule - I have an opinion.
 21 January 2019 08:44 PM
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alancapon

Posts: 7492
Joined: 27 December 2005

Originally posted by: IronFreely
Surely under BS7671 as everything after the isolator is the responsibility of the owner not the DNO

Yes and no. The DNO will design their network such that their overcurrent protection will cover as far as the customer's first overcurrent protection. Most DNOs define this as 3m cable length measured from the outgoing (load) terminals of the tariff meter or isolator (where they own it). Within this distance, a customer owned switchfuse is expected, fused to match the design of the customer's submain. We (a DNO) would refuse to connect a 10m unfused submain.

Regards,

Alan.
 21 January 2019 08:49 PM
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UKPN

Posts: 718
Joined: 17 January 2012

Let's get this right. 30 feet of 16mmsq single insulated through the cavity to the ceiling void. No overcurrent protection. No pscc protection. We haven't heard about the earthing/bonding but unlikely to have been completed. The new owner should arm them self with any certificates and also the builders specification. The builders specification will in all probability req the wiring to be to the DNO requirements. Start there, it will cause blushes.

Regards, UKPN, and mind how you go.
 21 January 2019 08:58 PM
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Alcomax

Posts: 450
Joined: 12 November 2009

Aside from route and length........

"single insulated"....and no sheath....surely not.
 21 January 2019 09:01 PM
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mapj1

Posts: 12039
Joined: 22 July 2004

And yet, presumably it magically got connected.
Depends on the sensitivity of your DNO of course, but it would be more usual to find a local customer side fuse, even if it ends up an identical rating to the company fuse. One could call the DNO and ask.

-------------------------
regards Mike
 21 January 2019 09:09 PM
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mikejumper

Posts: 2810
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What I've seen on new builds, where the CU is too far to be supplied directly by tails from the outgoing side of the meter, is a second external meter box installed directly above the one containing the meter.
The second box has the appropriate protective device only.
 21 January 2019 09:14 PM
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mikejumper

Posts: 2810
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Originally posted by: mapj1
And yet, presumably it magically got connected.

Could it have just been connected to the incoming side of the isolator and the contractor left to do their own thing on the outgoing side.
 21 January 2019 09:53 PM
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UKPN

Posts: 718
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I get used to these sad little quips re the DNO
from the forum comedian but Mike Jumper is correct, an isolator is fitted and the contractor connects the tails. After that, it's as I commented previously.

Regards, UKPN, and mind how you go.
 21 January 2019 10:53 PM
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John Peckham

Posts: 9097
Joined: 23 April 2005

Did someone summon up JP?

Assuming the DNO has consented to have 10m tails protected by their supply fuse which I very much doubt?

To "help the householder out" then Regulations 433.3.1 and 434.3 would indicate a couple of non-compliances.

As to the developer indicating compliance by production of the EIC perhaps the electrical contractor could explain? The EIC often in my view is only useful if printed on absorbent paper.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 21 January 2019 10:54 PM
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alancapon

Posts: 7492
Joined: 27 December 2005

Originally posted by: mikejumper
Could it have just been connected to the incoming side of the isolator and the contractor left to do their own thing on the outgoing side.

Conceivably yes, but we would still need a copy of the installation certificate, and reserve the right to carry out spot checks, to make sure everyone is behaving. This is a condition of making the supply live to the isolator.

Regards,

Alan.
 21 January 2019 10:58 PM
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alancapon

Posts: 7492
Joined: 27 December 2005

The householder is probably breaching their terms and conditions of supply too.

Regards,

Alan.
 21 January 2019 11:20 PM
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sparkingchip

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Joined: 18 January 2003

Tri-rated tails?
 22 January 2019 10:01 AM
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chrispearson

Posts: 1095
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Originally posted by: UKPN

We haven't heard about the earthing/bonding but unlikely to have been completed.


New build, plastic pipes, no bonding required.
 22 January 2019 11:38 AM
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AJJewsbury

Posts: 17795
Joined: 13 August 2003

the tails seem to be singularly insulated and only 16mm2

I presume by "singularly insulated" you mean they're insulated & sheathed single core cables (normal meter tails) rather than single insulated (unsheathed).

In some areas (like around me) the DNO default to 80A fuses - so 16mm2 might sort of be acceptable on that count.

There's still the technical issue that the cables have no overload/fault protective device within the BS 7671 part of the installation - and presumably the DNO won't have given consent for their device to be used for the purpose (so fails under 433.3.1 (iii) and 434.3 (iv)).
Oddly BS 7671 doesn't seem to have any obvious equivalent provisions for relying on the DNO's fuse for ADS.

No RCD would normally be needed on a TN system - unless additional protection in required (cables shallow concealed in a wall or run through a bathroom?) in which case a non-delayed 30mA type would be required.

- Andy.
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