C.U. Conversion to 17th Standard?

[ukants]

Would replacing the m.c.b.s on the non-r.c.d. protected side of a split load c.u. with r.c.b.o.s (and some re-configuring of the order of circuits) meet the 17th standard?
Not necessarily the cheapest option, I know, but it's the one method I rarely see mentioned and I wondered if there was any reason it would not meet the requirements.

 

[comms]

Yes it would, and the cost of rcbos is comming down.

 

[ban-all-sheds]

Would replacing the m.c.b.s on the non-r.c.d. protected side of a split load c.u. with r.c.b.o.s (and some re-configuring of the order of circuits) meet the 17th standard?

Define "17th standard"....

 

[securespark]

C'mon, Ban. He means BS 7671:2008.

 

[ukants]

Define "17th standard"....

Sorry BAN, missed the tweek I was busy.

C'mon, Ban. He means BS 7671:2008.

Yep that's the fella.

 

[ban-all-sheds]

C'mon, Ban. He means BS 7671:2008.

I know that.

What I meant was what does the 17th say about CU requirements? Where is a "17th standard" CU defined?

 

[Spark123]

I don't think it is, you just have to take the 17th edition and interpret the requirements from there as to what type of protection is needed and the best way to go about it.
Things like RCD protection for concealled cables burried less than 50mm will mean almost all circuits now need to be on an RCD, wether grouped on a couple of main RCCBs or usilising RCBOs is really up to the designer.
Smoke detectors iirc shouldn't share an RCD with socket circuits, hence some boards have a double RCCB arrangement for lights, sockets etc and a few non RCCB protected ways for RCBOs which can be used for things like the smokes.

 

[Click-Sure]

Electrium (Wylex, Volex, Crabtree) started advertising a Dual-Rccb High-Integrity board, and it looks like everybody else has nicked the term.

I think it is the way many electricians will go, all-RCBO installs won't become the norm until RCBO's get a lot cheaper. Some will opt for an old fashoned Split-Loader and use a few RCBO's.

If you have a very strict interpretation of BS7671:2008, (and indeed every addition that has recognised Current operated RCD's) then RCBO's are pretty much to only way to go, but thats another topic, one that has been bought up a while ago.

I'll get a sympathetic shout from JohnD on this one, whilst still not infallable, RCBO's are the future.

 

[plugwash]

nah if you have a very strict interpretation pyro or steel conduit and rcd sockets are the way to go

 

[JohnD]

I was wondering if cables with a braid and/or foil layer under the sheath would do the trick. It could presumably be used as the CPC. I used to come across cables like that in a previous life, I presume for electronic screening.

 

[securespark]

What I meant was what does the 17th say about CU requirements? Where is a "17th standard" CU defined?

A very good point, my shedophobic friend.

Personally (and I don't know if anyone would care to join me here), I don't believe that the "16th Ed" split boards were compliant and I feel the same way about the new split boards. Don't comply because one single fault can knock out many circuits.

The way I will be installing CU's from now on will be a 100A incomer board with RCBO's.

At least one person will be happy, won't you John?

EDIT: Sorry, Click. I posted this without scanning recent additions to the thread...

 

[Spark123]

I can see the advantage of using RCBOs, but the cost has got to come into it.
My personal opinion fwiw is it isn't a good idea to mix lighting and sockets on the same RCD, I'm leaning towards a bog standard split load board with single RCCB for sockets etc and RCBOs on the other side of the board for lights, smokes etc.

 

[Click-Sure]

I think space is going to become even more of an issue, particularly in some flats (same architect design) that I get contracts in from time to time where the CU's share a cabinet with DNO equipment.

 

[GaryMo]

I'm leaning towards a bog standard split load board with single RCCB for sockets etc and RCBOs on the other side of the board for lights, smokes etc.

Although it's currently no worse that it is now, I can see an advantage of upstairs and downstairs ring finals being on different RCD's, either by use of a twin RCD board or RCBO's (my personal preference).
I do like the look of the high integrity boards. They would be an obvious choice if the customer doesn't want to pay extra for a standard board full of RCBO's.

 

[Spark123]

I can see where you are coming from with the sockets on 2 different RCDs, just don't like the idea of lights and sockets mixed on an RCD. I suppose the only real way of doing this is using a full board of RCBOs, or a high integrity board with a number of unprotected ways for RCBOs. How many unprotected ways do they generally have?