17th Edition and RCD Protection

[TheScullster]

Hi all

Following a recent thread on House Revamp, the issue of RCD protection in all circuits came up. Looking at the Regs and the NICEIC toolbox guide, there is a clause which reads (roughly): "RCD protection required unless installation is under skilled supervision".

Does anyone know what this means in English?

Does that mean that the process of installing the cables must be carried out by a skilled person rather than an apprentice or cable puller?

Or maybe (and this only occurred to me this morning) that the installation after handover may be monitored/supervised constantly by a skilled person, who will know where cables run and not drill through them. In this instance RCD protection will not be required.

If the right interpretation is the latter, then does anyone know if I can get an MCBO (for a 6A lighting circuit) to replace a Hager MCB to fit in a Clipsal CU?

TIA

Phil

[John Stumbles]

What you said. AIUI RCD protection is required for cables buried less than

50mm in a wall and not in earthed conduit - IOW normal buried in chase in plaster.

Width-wise there are single-module-width RCBOs but they're all a lot longer than MCBs so may take some rearranging of wiring within an CU to fit.

AIUI standard practice for CUs to 17th edition is split load with both parts protected by RCDs.

[<me9]

If an existing ring circuit is modified (by adding extra sockets as permitted by prat P), as I understand it, the new parts have to comply with

17th edition. Does this mean RCDs must then be fitted, and thus adding additional sockets will no longer (in theory) be permitted without prat P certification?

[TheScullster]

"John Stumbles" wrote

Thanks John

Does this mean that any wiring now prompts a replacement or reconfiguration of the CU to comply with the "2 RCD" setup? I was hoping that simply replacing the lighting MCB with RCBO would suffice (as the sockets are on a dedicated ring already on the RCD side of the current box). How do you determine what circuits are placed which side of the split IYSWIM? Do the RCDs have different mA ratings either side?

Phil

[Andrew Gabriel]

Part P currently explicitly requires conformance to 16th Edition regs.

[Andrew Gabriel]

Part P explicitly calls up the 16th Edition regs.

[TheScullster]

Oh yes and if it is a re-vamp of an existing non-RCD circuit, does it still need to comply? Or is the dual RCD bit for new installs only?

Ta

phil

[John Stumbles]

It says "0.1 In the Secretary of State's view, the requirements will be met by adherence to ... BS7671:2001" (16th Edition) and "0.2 A way of satisfying the fundamental principles would be to follow ... BS7671:2001 ... or an equivalent standard" and so on. It seems to be worded so that it doesn't actually exclude the 17th edition (i.e. it doesn't say the Sec of State's opinion that it wouldn't be satisfied by the 17th) - or have I missed something?

[John Stumbles]

Good question. I don't know. [sigh! rustle of pages of BS7671:2008]

[Andrew Gabriel]

I think you're right, but equally, it's clear you can continue to use

16th Edition. (Might want to confirm with your BCO first though.)

I suspect "an equivalent standard" is there because in EU countries whose regs are harmonised, you are supposed to be able to use the regs from any other harmonised country. I knew of someone who used our 16th Edition regs in France under this scheme.

[Stephen Dawson]

BS7671:2008 is omly applicable for installs planned after 1st July 2008.

[ARWadworth]

There will be a lot more rustling of pages to come.

Adam

[Andy Wade]

those who don't know the Electrical Safety Council is the militant wing ^W^W charitable arm of the NICEIC.)

[Andy Wade]

by the awful noise at the start, it does get better:

[TheScullster]

"Stephen Dawson" wrote

Planned or executed? My plans have been on-going for about 4 years! The building re-works were carried out early last year. Does the electrical work therefore qualify as works "planned" prior to the

17th Ed? Since then I have done little electrically other than to re-instate cooker/existing remaining sockets and make safe lighting feeds.

Presumably I will have to chase the cooker cable down the wall in earthed steel conduit to comply?

Phil

[dennis]

Have you seen how stupid some of the answers are though?

Like the one where they say an installer can't choose between the 16 and 17 editions selectively.. of course they can.. just do two installations. It may not be in the spirit of the rules, but the rules are pretty stupid anyway.

[dennis]

Looks like all house wiring needs to be in SWA to avoid those pesky RCDs. It will do wonders for the environment. ;-)

[Andy Wade]

There are alternative shielded cables that you could sensibly use, such as 'Flexishield'

Prysmian's 'Earthshield', FP200 or even MICC.

Don't forget though that you'll still need 30 mA RCDs for all general-use sockets and for all bathroom circuits, regardless of the wiring system used.

[John Stumbles]

Yes, in terms of Part P, but I think you'd then have to qualify your installations as being deviations from BS7671 (specifically BS7671:2008 being the current version). If I'm extending - particularly by extending the cables of - an existing circuit in old colour codes I'd be tempted to use old-colour-coded cable for the extension (a) because it does less violence to the principle of least suprise than new colour code, (b) because I've got a shedload of it to use up :-) and I guess that would fall under being a deviation. I'd want to check that with some gurus though.

[Andrew Gabriel]

John, I think you're missing my point. Part P doesn't reference the _current_ version of BS7671, it specifically references BS7671:2001 which as you said, is the 16th Edition.

In my limited experience of commercial electrical contacts since the colour change, albeit including one multi-million pound one, safety officers seem to demand that installations don't mix old and new colours, so the wiring was all done in the old colours, in spite of what the IEE specified/wanted. I talked with the project manager, and his comment was that safety always takes precidence over the regs.

In the period of overlap of old and new colours, we came across notices fixed in wiring closets of one large well-known company saying it was forbidden to use the new colours on these premises, but I've not been back since to see if they're still there.

I also overheard some electricians specially ordering cable in the old colours at a trade counter, which they were required to use in a local hospital. I don't know the reasoning there, but some places like hospitals were already using what became the new colours to identify special circuits, such as UPS (life support) circuits, or clean appliance circuits, etc.