Meter Tail Length

[enlighting]

Afternoon all,

Carried out an EICR yesterday, on the job I doscovered the consumer unit to be located in the kitchen and the incoming supply under the stairs. The tails feeding the board look to me to be just over 3 meters perhaps 3.5. But it is difficult to tell as they are ran in an internal wall.

What coding is recommended and what remedial action required.

Im thinking C2 with a fuse fited between the isolator and the consumer unit.

Cheers

Dave

 

[HandySparks]

Possibly just a C3 for lack of RCD protection to the buried cables? I wouldn't worry over 0.5m additional length; it's not specified in BS7671 anyway.

 

[davesparks]

What is the potential danger that you can forsee here that you feel warrants a C2

 

[Deleted member 26818]

Yes a code C2.
3m is the max allowed in BS7671.

 

[davesparks]

Yes a code C2.
3m is the max allowed in BS7671.

What is the potential danger that requires a C2 and which regulation number?

 

[Risteard]

Im thinking C2 with a fuse fited between the isolator and the consumer unit.

Something which is not non-compliant with the Wiring Regulations CANNOT be coded.

 

[Deleted member 26818]

It is non-compliant.
Not sure of the Reg No. I'm in a cafe, so don't have my copy of BS7671 to hand.
The Section it is under is called position of overload device, or similar.

 

[Risteard]

It is non-compliant.
Not sure of the Reg No. I'm in a cafe, so don't have my copy of BS7671 to hand.
The Section it is under is called position of overload device, or similar.

Don't have a copy on me either I'm afraid.

 

[Deleted member 26818]

Sections 433.2 and 434.

 

[Guest55]

i wouldnt be coding anything unless one can confirm the tails are indeed greater than 3mtrs rather than a rough estimation on a cable route you cant see.

and its a C3 at worst if the tails are current rated above the dno fuse size.

that said , no rcd protection for cables hidden within the fabric of the wall without earthed mechanical protection would probably warrant a C2.

and reg 433.2 doesnt apply to CU tails as there is no reduction in cable size along its path from meter to CU.

so im still not convinced the issue is within the remit of an inspection conducted to bs 7671 to begin with......

 

[Octopus]

The Elecsa helpline once aid that just over 3m isn't a problem. So what they say goes!

 

[Deleted member 26818]

A number of people believe that 433.2 and 434 do not apply in these instances.
I do not understand why people have this belief, as they must be aware that the distribution network does not fall within the parameters of BS7671?
I believe that this has promted the network distributors to now insist oversized conductors of 25mm be installed.
There does appear to be a misconception that the network operators protective device is intended to provide protection for the installation, however in fact it is there to protect the network operator's equipment.
It is very rare that the network operators will agree for their device to be used to protect an installation, when they do allow such, they impose quite severe restrictions and conditions.
From BS7671's view point the installation begins at the Meter, and any protective device upstream from the Meter is of no consequence.
As such, if the Meter Tails are longer than 3m, a protective device is required along that run.
The OP has also indicated that the tails are run in a cavity wall, which is something the network distributors do not allow.

 

[Andy78]

A number of people believe that 433.2 and 434 do not apply in these instances.
I do not understand why people have this belief, as they must be aware that the distribution network does not fall within the parameters of BS7671?
I believe that this has promted the network distributors to now insist oversized conductors of 25mm be installed.
There does appear to be a misconception that the network operators protective device is intended to provide protection for the installation, however in fact it is there to protect the network operator's equipment.
It is very rare that the network operators will agree for their device to be used to protect an installation, when they do allow such, they impose quite severe restrictions and conditions.
From BS7671's view point the installation begins at the Meter, and any protective device upstream from the Meter is of no consequence.
As such, if the Meter Tails are longer than 3m, a protective device is required along that run.
The OP has also indicated that the tails are run in a cavity wall, which is something the network distributors do not allow.

section 433.3.1 (iii) says that overload protection may be omitted where a service fuse is agreed to afford protection to any run between it and the main distribution point of the installation. i.e. the cable CCC exceeds that of the service fuse.

 

[Deleted member 26818]

Yes, when it is agreed.
If it has been agreed then there will be a written agreement with a list of conditions and stipulations as long as your arm.
I doubt very much that such an agreement would be made for a domestic installation, where there are no statutory requirements for who has control of the installation.

 

[Andy78]

Yes, when it is agreed.
If it has been agreed then there will be a written agreement with a list of conditions and stipulations as long as your arm.
I doubt very much that such an agreement would be made for a domestic installation, where there are no statutory requirements for who has control of the installation.

I think it's agreed with our DNO then. I asked them about this recently and they had no knowledge of any 3m rule or any stipulation for fusing of tails of any length.

 

[Guest55]

A number of people believe that 433.2 and 434 do not apply in these instances.
I do not understand why people have this belief, as they must be aware that the distribution network does not fall within the parameters of BS7671?
I believe that this has promted the network distributors to now insist oversized conductors of 25mm be installed.
There does appear to be a misconception that the network operators protective device is intended to provide protection for the installation, however in fact it is there to protect the network operator's equipment.
It is very rare that the network operators will agree for their device to be used to protect an installation, when they do allow such, they impose quite severe restrictions and conditions.
From BS7671's view point the installation begins at the Meter, and any protective device upstream from the Meter is of no consequence.
As such, if the Meter Tails are longer than 3m, a protective device is required along that run.
The OP has also indicated that the tails are run in a cavity wall, which is something the network distributors do not allow.

i still dont get where your C2 comes from ?

if 3mtr tails are considered safe / acceptable , where does the risk / danger come from if they are 3.5mtrs ?

have they suddenly become a threat to the installation user for being 0.5 mtr longer ?

 

[Deleted member 26818]

A code C1 is applied for when there is an immediate danger.
A code C2 is applied where there is a potential for danger.
A code C3 is applied in instances where the Regulations were complied with at the time of design/construction, but due to changes in the requirements, no longer comply.

As far as I am aware this situation has never complied with any Regulations.
As such codes C1 and C3 are not applicable, leaving only code C2 as an option.

Not certain which DNO you are referring to Andy?
However any DNO have a statutory obligation to allow connection for installations which comply with BS7671.
However, that said the DNOs do not work under BS7671, so there is no reason for anyone to have any knowledge of the requirements of BS7671.
I do know that individual DNOs and the association of meter operators produce guidelines indicating the maximum length they allow. Most of which can probably be found onLine.

Here is a link to the FAQs page for the association of Meter Operators:
http://www.meteroperators.org.uk/faqs

At the end of the day compliance with the Regulations is not statutory.
If you want to interpret the Regulations, as you see fit, that is your option, I cannot force you to comply, or to not misinterpret the Regulations. I can only offer advice and my considered opinion, based on my limited knowledge and experience.

 

[Guest55]

that was absolutely no answer at all to my question.

and your definition of C3 is incorrect , it is referred to as "improvement recommended" , there is no particular tie in with any edition of the regs for it to be used.

which seems a considerably more suitable defect code for the length of tails that have not been confirmed to be actually longer than 3 mtrs.........

 

[Gavin A]

Yes, when it is agreed.
If it has been agreed then there will be a written agreement with a list of conditions and stipulations as long as your arm.
I doubt very much that such an agreement would be made for a domestic installation, where there are no statutory requirements for who has control of the installation.

I thought the point of the 3m rule was that it was automatically agreed by the DNOs up to 3m.

 

[Deleted member 26818]

Sorry Biff, I edited my post to include the link whilst you were posting.