Distribution circuit question

[LlandrilloSpark]

I'm running a 30 metre length of three core 16mm armour to feed a garage conversion which could have a high loading.
The cable will be run from the external meter box where I will split the meter tails via a Henley
The problem is There is naff all room in the box and I can't fit a switched fuse in there to protect the armour as the main cut out is 100A
Can I put the switched fuse of another suitable protection device at the other end to protect against overload?
Cheers

 

[malcolmsanford]

No you can't you will need to protect that sub main

 

[telectrix]

can yo not fit a switch fuse in a suitable IP65 adaptable box on the wall close to the meter box ?

 

[LlandrilloSpark]

Cheers guys IP 65 it is then

 

[Chr!s]

I'm running a 30 metre length of three core 16mm armour to feed a garage conversion which could have a high loading.
The cable will be run from the external meter box where I will split the meter tails via a Henley
The problem is There is naff all room in the box and I can't fit a switched fuse in there to protect the armour as the main cut out is 100A
Can I put the switched fuse of another suitable protection device at the other end to protect against overload?
Cheers

It is possible to do it that way. There are requirements though.

Regards Chris

 

[Guest123]

I dont think the DNO would be too happy with that arrangement, if they found out of course.:biggrin5:

There wouldn't be anything wrong with what you suggest, further in to an installation but, not at the origin IMO.

 

[Chr!s]

I dont think the DNO would be too happy with that arrangement, if they found out of course.:biggrin5:

There wouldn't be anything wrong with what you suggest, further in to an installation but, not at the origin IMO.

I see no reason for the DNO to have issues. The installation if designed correctly would meet the requirements of BS7671.

Regards Chris

 

[Rockingit]

At least you didn't ask THAT dreaded question........!!

And yes, you need to protect the cable so will have to find some form of additional box to house it in.

 

[Chr!s]

At least you didn't ask THAT dreaded question........!!

And yes, you need to protect the cable so will have to find some form of additional box to house it in.

Are you sure about that ?


Regards Chris

 

[Guest123]

The way I see it, the first 30M of distribution cable would be relying on their service fuse for protection against short circuit, albeit with the added overload protection at the load end.


I'm not saying it's wrong or non compliant but, knowing the DNO as we do they are bound to come across it, see a cable directly connect to their service fuse with no additional protection visible, put 2 & 2 together, make 49 and throw the toys out of the pram.

 

[ackbarthestar]

At least you didn't ask THAT dreaded question........!!

And yes, you need to protect the cable so will have to find some form of additional box to house it in.

Use a 4-core swa and then THAT question is or isn't answered :smiley2:

 

[spark 68]

Just a Thought,

He can put the switch fuse/Isolator within 3M of the origin, suitably labelled of course, I don't know if that will help the Op any, as I cannot see the installation

 

[Chr!s]

The way I see it, the first 30M of distribution cable would be relying on their service fuse for protection against short circuit, albeit with the added overload protection at the load end.

True Lenny, though everyone seems to be happy using the Dnos fuse for short circuit when using standard circuits, after all its the fuse which Annex Za uses to limit Let through and allows the consumer units to be rated higher, also the standard circuits where the Dno's fuse is providing back up protection, the i2t is used for determining CSA.

Do you have discrimination(short circuit) between a 32 amp type B MCB and a 100 amp 1361, what about larger MCB's, on a short the Dno's fuse is now providing short circuit protection to your circuits.


I'm not saying it's wrong or non compliant but, knowing the DNO as we do they are bound to come across it, see a cable directly connect to their service fuse with no additional protection visible, put 2 & 2 together, make 49 and throw the toys out of the pram.

Regards Chris

 

[Guest123]

Just a Thought,

He can put the switch fuse/Isolator within 3M of the origin, I don't know if that will help the Op any, as I cannot see the installation

Absolutely but, the issue was the service head being in an external meter cabinet with no additional room for a switchfuse.

Mounting an additional enclosure adjacent to the meter cabinet has been suggested.

 

[spark 68]

Mounting an additional enclosure adjacent to the meter cabinet has been suggested.

Agreed Lenny, but I was thinking more on the other side of the wall to the DNO's cabinet, ie through the wall