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

 

[Chr!s]

Well id suggest he utilizes 433.2.2 part (i).

Regards Chris

 

[Guest123]

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

I took it that he couldn't/didn't want to go internally with it at all....

 

[Guest123]

Well id suggest he utilizes 433.2.2 part (i).

Regards Chris

He could & I'm not disputing that, I mentioned it earlier. The only point I raised was regarding the DNO and their inability to se the wood for the trees. They want (or at least mine do) to see the additional protection within 3M of their service head, end of. They wont be told any different and I just wanted to make the OP aware of it.

BS 7671 isn't the be all & end all.

 

[Chr!s]

He could & I'm not disputing that, I mentioned it earlier. The only point I raised was regarding the DNO and their inability to se the wood for the trees. They want (or at least mine do) to see the additional protection within 3M of their service head, end of. They wont be told any different and I just wanted to make the OP aware of it.

BS 7671 isn't the be all & end all.

Well just remind them of this;

1 Definition Network ESQCR

Consumer’s installations in buildings are not intended to be included in the definition. Such installations should comply with the requirements of BS7671 Requirements for Electrical Installations or those of other relevant standards. Electrical distribution systems on offshore installations are also excluded from the definition, e.g. oil rigs.

So tell them to concentrate on there network and you will concentrate on your installation to the relevant standards.

As for there equipment in a premise then there is also this;

ESQCR

Equipment belonging to distributors and meter operators which is installed on consumers’ premises must be suitable for itspurpose and safe. Examples of such equipment include: cables, meters, distribution boards, isolators and switches.Such equipment must also be electrically protected by fuses, cut-outs or circuit breakers. For safety and technical reasons the protective device should be situated as close as reasonably practicable to the supply terminals. Where flats are supplied by rising mains, duty holders should ensure that all equipment upstream of the supply terminals at each flat benefit from adequate electrical and mechanical protection.
In order to demonstrate compliance with the requirements of regulation 24(1) duty holders should adopt the standards of construction and installation necessary to comply with BS7671 Requirements for Electrical Installations.

Regards Chris

 

[Gazzdid]

Wouldn't that mean the only protection the 16mm would have is the 100A service fuse? I wouldn't even consider that as an option! I would also be doing everything I could to rcd protect the armoured.

 

[spark 68]

I would also be doing everything I could to rcd protect the armoured.

I agree about protecting the submain, but you don't want an RCD at source (Why?) as it would/could trip the whole of the remote installation on an earth fault which is a good 30 M away !, no, RCD's local if required is far better IMO, besides if the RCD was at source would this not contravene the regs wrt circuit segregation ? (314.1).

Unless of course the Installation was TT, and then a time delayed 100mA may be required

 

[telectrix]

why on earth would you want to RCD the SWA?

 

[LlandrilloSpark]

Can of worms lads?

Gazz I'm not wet behind the ears you know I know about the 100A and the 16mm , and why would I RCD a distribution circuit in Armour????

 

[SPARTYKUS]

Wouldn't that mean the only protection the 16mm would have is the 100A service fuse? I wouldn't even consider that as an option! I would also be doing everything I could to rcd protect the armoured.

Gazzdid, please explain your RCD suggestion on the armoured cable....?

 

[DPG]

I would have thought the 100A service fuse protecting the 30M run was a big no-no. If someone puts a spade through the SWA, the supply for the whole house is lost until the DNO comes out? Daz.
PS I'm no expert, so feel free to pull this comment to bits :smiley2:

 

[telectrix]

I would have thought the 100A service fuse protecting the 30M run was a big no-no. If someone puts a spade through the SWA, the supply for the whole house is lost until the DNO comes out? Daz.
PS I'm no expert, so feel free to pull this comment to bits :smiley2:

nothing wrong with your comment. a 60A sw fuse is the answer.

 

[Rockingit]

Hence why you protect the cable using an over-current device.

 

[DPG]

Yep fair enough. Just saw a couple of posts on page 1 that seemed to be saying you don't need the fuse - seemed strange. Daz

 

[Guest123]

Yep fair enough. Just saw a couple of posts on page 1 that seemed to be saying you don't need the fuse - seemed strange. Daz

The question wasn't should we or should we not install it as obviously we should. We were debating on where it should go in relation to the service head.

Overcurrent protection doesn't necessarily have to be at the origin of a circuit, (433.2 refers) but when it comes to the DNO, they are a law unto themselves so in this instance it would be best IMO to place it at the origin.

 

[DPG]

Just trying to get this straight in my head so apologies!

If the overcurrent protection is at the end of the 30M run, the scenario of a spade through the SWA will not result in the fuse blowing, but will blow the service fuse.

I thought if the 60A switch-fuse was protecting the cable it should go at the origin?

Daz