Earthing of metal sheathing

[Top Cat]

Got a job coming up where there will be an outside meter box and new consumer unit in hallway (about 4 Mtrs). The only route i can take (and the customer wants) is to chase tails in wall up to D/B.

Was thinking of RCD protection in meter box as cables will be less than 50mm but then i wondered if you earthed the metal sheathing would that be OK to then put a KMF in meter box?

 

[GaryM]

522.6.101(v)?

522.6.102

 

[sedgy34]

HEY TC

kmf mains and sheath the tails with 3/5MM sheathing they do sell it,also its in the zone of the DB this will suffice (no need to earth it)

 

[Top Cat]

but if not complying with 522.6.101 i,ii,iii,iv, shall have RCD - 522.6.102

here endeth the lesson.

i, or ii,or iii,or iv,or, what about v?

 

[GaryM]

i, or ii,or iii,or iv,or, what about v?

Have you read 522.6.102?
(v) must be accompanied by (i, ii, iii or iv) to omit the requirement for an RCD if the installation isn't under the supervision of a skilled or instructed person.

 

[Top Cat]

Have you read 522.6.102?
(v) must be accompanied by (i, ii, iii or iv) to omit the requirement for an RCD if the installation isn't under the supervision of a skilled or instructed person.

Yes just read that (and i am starting to lose the argument!) but that relates to 0.4ms, surely it's 5 seconds?

 

[Top Cat]

I thought i was losing the argument but the silence is deafoning!

 

[Top Cat]

but if not complying with 522.6.101 i,ii,iii,iv, shall have RCD - 522.6.102

here endeth the lesson.

Why???

 

[sedgy34]

HEY TC

Good luck with the kmf rcd lol 5mm steel capping is cheapest option my friend

 

[SPARTYKUS]

Scaffold pole.

 

[Top Cat]

HEY TC

Good luck with the kmf rcd lol 5mm steel capping is cheapest option my friend

Hi sedgy thanks for that. As i said in early post, "just a hypothetical question" Got slagged off by some and got replies within seconds when they thought they were right. As they were losing the argument...........Silence! I thought i was losing the argument and was prepared to say so. If they can prove me wrong then fair play i will hold my hands up and congratulate them.

 

[Richard Burns]

I think it is the use of your word sheathing; if the cable is sheathed in metal suitable for use as a protective conductor then this does not need RCD protection.
If the cable is enclosed in metal suitable for use a protective conductor that acts as conduit, trunking or ducting then an RCD can be omitted.
I think the use of steel capping would not comply because it does not enclose the cable only covers it (however it should be just as safe unless the wall is less than 50mm plus your chase deep.)
Mechanical protection is fine if you can fit it in place, say 5mm steel capping.

 

[GaryM]

Yes just read that (and i am starting to lose the argument!) but that relates to 0.4ms, surely it's 5 seconds?

It's not an argument, just a friendly discussion. Well it is on my part!
You lost the discussion from the word GO. Just read 522.6.102 again, it's very simple to understand. You can't omit an RCD where cables are within a safe zone (522.6.101(v)) and covered with standard metal capping as that wouldn't comply with 522.6.101(iv).
To omit an RCD and comply with 522.6.102 and 522.6.101(v) you also must comply with 522.6.101(i, ii, iii or iv).

All the above relates to an installation not under the supervision of a skilled or instructed person. Domestic in this case.

Where the hell did you find a link to the above and "0.4ms, surely it's 5 seconds"? Why would that change things? I also assume you mean 0.4s and not ms.