Max length of meter tails

[8ballpoolplayer]

Ive been asked to look at the electrical installation at a large 5 bed property with an attached annexe that the owners are converting into a 2 bed holiday let.
There's one supply cable that comes into the annexe for the entire property .
This is currently routed via a single meter to a CU .
2 sub boards are run from this , 1 for the annexe and 1 for the main house.
Trouble is , the house CU (20mtrs away) has been run using 10mm cable which is obviously insufficient. I would want to run this using 25mm CSA meter tails instead (after doing cable calcs) , via a separate meter , directly to the house's CU .
Is this allowed , can't find the regs covering max length of meter tails .
I've loads of other questions but will see what replies I get as they may answer some of these questions .
A big thank you if you've read this far !

 

[telectrix]

i think that there's no reg. to cover that, but DNOs usually request/demand that tails over 3m in length are protected by a switch/fuse with the fuse being of a lower rating than their supply fuse.

 

[Taylortwocities]

25m long metre tails? Are you mad?

25mm SWA is what you need. And a switchfuse at the origin.

 

[Devonchris]

I was always led to believe that meter tails, as the name implies, were just that. Ie. Short lengths from the meter to your first local termination, whatever that might be. Anything else after that are distribution circuits.

 

[Octopus]

I think this is another "failure" of the regs ................. and therefore the 3m length is common sense

 

[johnduffell]

The 3m rrul is just so the dno can take the load off and know they've done it before pulling the fuse.

 

[Wilko]

Time for some switch fuses and SWA

 

[Taylortwocities]

How I wish that I had mentioned that

25mm SWA is what you need. And a switchfuse at the origin.

 

[Gavin John Hyde]

agree with the above comment, 25 metres of tails cables is a very expensive method of achieving what you want to do, swa or concentric would be my choice

 

[Judd]

A 25 metre run of 25mm SWA might be extremely difficult to run through a house, split con might be easier although personally I can't stand terminating it.

 

[Andy78]

This is covered by the regs. This is a circuit like any other and should have adequate overcurrent and fault protection. The DNO usually allow use of their fuse up to 3m. See 433.3.1 (iii)
The 3m rule has basis in the regs also as the maximum length for a cable with the device for protection of overload not at origin of the circuit. 433.2.2 (ii)