SWA armour connection in metal distribution board.

[ban-all-sheds]

What if the designer/installer wishes to follow the route of 543.1.4, and the armour is too small?

Then he is stuffed, just as he would be trying to use 543.1.4 with twin and earth really.

Why is he, if he can use one of the cores that is the right size?

do you have to?

Yes - I would say we do.

Is there a reg?

 

[Spark123]

I thought you were meaning when only the armour was being used which is often too small to comply with 543.1.4. There is nothing wrong with using one of the internal conductors to automatically comply with 543.1.4 if that is what you are meaning.

afaik the actual requirement to earth the armour comes under the standard for the cable such as BS5467

 

[Adam_151]

Yeah, make sure your armouring is earthed good:

 

[Spark123]

Is that high integrity earthing?

 

[shetland]

Even if the armour isn't used as the cpc, it should still be earthed because, as Spark 123 says, it should be treated as an exposed conductive part in the same way that it is required to earth the braid on an sy cable.

 

[ColJack]

it's not exposed if you've got all the boots and things on properly..

 

[shetland]

Not according to Guidance Note 8...

 

[Spark123]

Yep, GN8 does the regard the armour as an exposed conductive part.

Also BS5467 annex B, B7 says that provision should be made for earthing of the armour at the supply end by means of a metallic bond of adequate conductance...

 

[ColJack]

if it's all shrouded properly and is connected at both ends to something plastic then how can it be exposed?
that's like saying that the busbar in the CU is exposed even when the covers on...

 

[electronicsuk]

if it's all shrouded properly and is connected at both ends to something plastic then how can it be exposed?
that's like saying that the busbar in the CU is exposed even when the covers on...

It's an exposed conductive part by definition as it can become live in the event of failure of basic insulation. Your analogy doesn't really work, as the cover on a consumer unit can't (normally!) be removed without the need for a tool, whereas the shroud on a gland can sometimes come off on it's own without any intervention if it's been weathered enough.