17th edition regs /RCBO's/CB's/total rewire/ D.I.Y.??

[knobbiewilliams]

Hello all, need some info about what the 17th edition regs have added to the 16th edition as I am about to re-wire a whole house.
I re-wired my own house to full regs and got it signed off but don't know about what 17th edition says about RCBO's.
I will be fitting out with a split load cb with each side having it's own 63A 30mA RCD's with one side protected with a RCBO.
I take it the side with the RCBO has to protect the high risk areas such as bathroom areas and its lighting.
As both these circuits will be upstairs this poses no problem but...outside lights and kitchen??; do these areas and their circuits require an RCBO also.
Locations containing a Bath or a Shower particularly the changes from the 16th Edition are substantial:

Zones 0, 1 and 2 as defined in the 16th Edition are retained. Zone 3 is being removed.
OK, I can get this, they are tightening up on what can go where.

New regulations require all circuits supplying equipment in the bathrooms to be protected by 30 mA RCD's.
Yes, I understand this also, the cb will have two-one per split load, so I have got two fuseboards with 63A 30 mA RCD protection
over the MCB's they power within one big box of tricks.

All cables buried in walls surrounding bathrooms regardless of the points they are serving have to be protected by 30 mA RCD's.
Sure,new cb's have one or two RCD's as standard so all the last points are covered but this bit I do not get.

Supplementary Bonding between metallic service and waste pipes and the earth connections of equipment is no longer required providing the main
bonding of services within the property is in place and the metallic pipework can be proved by testing to be continuous.
This means that the need for green and yellow cables in bathrooms is unlikely to be necessary.

So..call me stupid (please feel free), do I actually require a cb with RCBO's covering all circuits or is this overkill and where did the earth rod go in all this.
Is it now defunct or 'an also' because the regs also state that you should design a system that will not trip out on a regular enough basis to become a nuisance.

After all this can begin I know that I will have to inform the building control board from my local area, but I do not wish to fall flat on my face on day one over something silly.
Please can anyone help me out with this
Regards, Rob/Mug/Tea maker/Dogsbody/Labourer/Foreman...oh yes...and Plumber but thats another story!

 

[electronicsuk]

I will be fitting out with a split load cb with each side having it's own 63A 30mA RCD's with one side protected with a RCBO.

What do you mean by this? Are you saying that you will fit a high integrity board with 3 sets of busbars, two protected by a pair of RCDs, and a third fed directly from the main isolator onto which you will fit RCBOs?

There is no point whatsoever in fitting RCBOs onto the busbars that are already RCD protected.

I take it the side with the RCBO has to protect the high risk areas such as bathroom areas and its lighting.

I'm not sure you fully understand what an RCBO is. It simply combines the functions of an MCB and RCD into a single unit. As you are aware, all new bathroom circuits must be RCD protected, and one way to achieve this is by feeding bathroom circuits from an RCD protected MCB in the CU.

As both these circuits will be upstairs this poses no problem but...outside lights and kitchen??; do these areas and their circuits require an RCBO also.

If you mean "do these circuits require RCD protection?" then the answer is yes and no. All socket outlets in the house must now be RCD protected, which differs from the 16th where it was only necessary to RCD those that could potentially supply portable equipment outdoors. In that respect, you will need to RCD protect the kitchen.

There is no requirement for the kitchen lights, or any lights in the house outside of the bathroom, to be RCD protected. However, unless you think you can chase in all your cables more than 50mm deep or wire in earthed steel conduit/SWA/etc, you have no choice but to RCD protect.

Outdoor lighting will depend on how you install it. If it's a simple case of cable coming through the wall and straight into the fitting, and assuming the manufacturer doesn't specify otherwise, there is no need to RCD. Equally, if you can't come directly into the fitting, you can avoid the need for earth leakage protection by selecting a cable such as SWA which provides earthed mechanical protection.

Personally, I'd choose to protect outdoor lighting circuits using an RCBO straight off the non-RCD side of the CU. This will avoid nuisance trips of the main RCDs, and provides as good level of safety. Mind you, even if I were a domestic electrician, I probably wouldn't install a high integrity CU full stop. Fully loaded with RCBOs is the way to go.

New regulations require all circuits supplying equipment in the bathrooms to be protected by 30 mA RCD's.
Yes, I understand this also, the cb will have two-one per split load, so I have got two fuseboards with 63A 30 mA RCD protection
over the MCB's they power within one big box of tricks.

Er...?

All cables buried in walls surrounding bathrooms regardless of the points they are serving have to be protected by 30 mA RCD's.

That's news to me. Have you got a reg number for it?

Supplementary Bonding between metallic service and waste pipes and the earth connections of equipment is no longer required providing the main
bonding of services within the property is in place and the metallic pipework can be proved by testing to be continuous.
This means that the need for green and yellow cables in bathrooms is unlikely to be necessary.

You still need to ensure all bathroom circuits are RCD protected if you want to avoid supplementary bonding.

So..call me stupid (please feel free), do I actually require a cb with RCBO's covering all circuits or is this overkill and where did the earth rod go in all this.

Not overkill at all in my opinion, although some sparks may disagree. My interpretation of the regs is that a dual RCD high integrity CU is barely compliant anyway, and just seems to be what has been thrust down on us by manufacturers as a way to become compliant with the 17th edition. In a way, not all that different from Hager's maintenance free junction boxes, which most people on this forum agree are unsuitable for use in inaccessible locations.

As for the earth rod, that only comes into the equation if you have a TT supply. If you are TT, it would be worth asking your supplier if you can be converted to PME before you go any further with your planning. If you choose to remain on a TT supply, ALL circuits will need to be RCD protected whether you like it or not.

Is it now defunct or 'an also' because the regs also state that you should design a system that will not trip out on a regular enough basis to become a nuisance.

No system should trip out on a regular basis. The intention of these new regulations is to ensure that if anything does trip, it should affect as few other circuits as possibly, and in an ideal world this would mean the faulty circuit should be the only one to be disconnected. Hence my dislike of dual RCD boards.

 

[mikhailfaradayski]

Hmm, i like that you do seem to have a reasonable grasp of whats going on and im sure you would have no problem adding the odd socket or lamp etc.

IMO there is far too much knowledge of surrounding info needed to tell someone how to do a full rewire, you could be here for months getting more and more conflicting opinions on how do things.

If you dead set about doing this yourself, you stand to save a couple of grand on labour charges. Surely thats enough saved for you to splash out on a copy of the regs, OSG and a nice 'sparkies guide', should set you back less than £100, you can get the bulk of info from that and come here to ask questions to fill in a few blanks..

just a thought

 

[1john]

you wont fall flat on your fac on day one worrying about consumer units, thats the last thing to install.

can you explain to us what you beleive an RCBO is?

you certainly wouldnt provide one RCBO to supply an entire installation which is what you seem to have suggested.

 

[Chri5]

Hello all, need some info about what the 17th edition regs have added to the 16th edition as I am about to re-wire a whole house.
I re-wired my own house to full regs and got it signed off but don't know about what 17th edition says about RCBO's.

You say you've rewired and then got it signed off- then you say your about to start a rewire of a whole house ?

Either you have done the work or not- or are we talking about another property being done for commercial gain ?

Could I suggest you buy the 17th OSG, read it and then come back with questions ?

Your post makes it clear hat you wish to learn, but haven't quite grasped the finer points.

 

[1john]

Having re-read your post i think you should politly ask your customer to employ a competent, qualified and registered electrician to do their re-wire.

 

[knobbiewilliams]

thanks for the fast response chaps,have to go to London today to pick up a new car,i will sit down tonight and clean up my post, it was done early morning and i think i might have stated a few things wrong such as the type of cu i will be using is a high integrity split load with two RCD's-one for each load and an RCBO. An RCBO is an RCD and an MCB in one unit so makes the circuit it serves a mini split load yes/no? but i have heard doubts about their reliable operation/trip speed and correct application...this is an early morning(i had a late one) post so bear with me until i get back tonight and i will answer all your posts as best i can
once again....thanks for the swift reply

 

[ban-all-sheds]

I re-wired my own house to full regs and got it signed off

What do you mean by "got it signed off"?

Did you end up with EIC(s) certifying that to the best of the knowledge and belief of someone competent to make such a determination that it was designed, installed, inspected and tested in accordance with BS 7671:2001?

If not then it was not in compliance.

If you did, then your level of competence must be such that you should have no problems whatsoever in understanding what has changed in the 17th.

but don't know about what 17th edition says about RCBO's.

The get a copy, and an OSG and EGTTBR, and read what it says. No other course of action is acceptable for someone planning to completely rewire a house.

As I said - if you were truly competent to comply with the 16th in a major job like this then you will find the changes in the 17th easy to grasp.


But IMO the questions you are asking, and the assumptions you seem to be making do not show that you possess any where near the level of knowledge required for a job like this, nor ever did.

After all this can begin I know that I will have to inform the building control board from my local area

Not simply "inform" - you have to submit a notification detailing how you will comply with the requirements of the Building Regulations - Parts A, B, C, L and P are the ones most likely to apply, but others may also be relevant.

They then have to approve your plans, but with Part P verification many LABCs play fast and loose with the law, and the official guidance, and you might find they place obstacles in your way, so you should get the Building Regulations approval sorted out asap, in case it affects how you go about this.

 

[electronicsuk]

i think i might have stated a few things wrong such as the type of cu i will be using is a high integrity split load with two RCD's-one for each load and an RCBO

Still not making complete sense, but I think I know what you mean. If you could provide a link to or picture of the product in question, that would be helpful

An RCBO is an RCD and an MCB in one unit so makes the circuit it serves a mini split load yes/no?

An RCBO is indeed a combined MCB and RCD, but it doesn't make the circuit a 'mini split load', it's completely the wrong terminology to apply here. Split load refers to the loads (on the MCBs) in the consumer unit being split, whether it be between two RCDs, or an RCD and the main isolator as would have been common in an installation to the 16th.

but i have heard doubts about their reliable operation/trip speed and correct application

Can't say I've heard anything like that myself - presumably BS7671 wouldn't reference to and allow the use of RCBOs as an earth leakage/overcurrent protective device if they weren't up to the job.

 

[knobbiewilliams]

once again, thanks for all your replies. Now 22:30 and have just got back from London with a new (old) car,lots of rain,diversions and traffic.

lots of threads coming back to me,hard to reply to them all but here goes:
in response to electronicsuk:

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• knobbiewilliams
• 29 Nov 2009
• 1

1 x 100A DP Sw,2 x 80A 30mA RCDs, 1 x 40A, 4 x 32A, 2x16A, 3 x 6A.

this is my other option:

Untitled

• knobbiewilliams
• 29 Nov 2009
• 1

1 x 100A DP Switch, 2 x 63A 30mA RCD,1 x 40A, 2 x 32A, 1 x 16A, 3 x 6A MCB's,
1 x 6A RCBO, 1 x Spare RCD Protected Way,1 x Unprotected Spare Way.

I might have to juggle items within the new CB's to match the houses requirements.

this is what I'm replacing!

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• knobbiewilliams
• 29 Nov 2009
• 1

and this is only the tip of an old iceberg,10 junction boxes in this floor space,many more 'additions' scattered all over the house along with taped up live 2.5 & 6mm wire in the floor space and light switches just hanging in mid air!!
one we found in a stud wall supplying an upstairs light switch was just single strands of unsheathed red and black wires with no earth.


Ban all sheds:
got a qualified spark to inspect,check and test with paperwork all work i carried out on my house,not sure of the BS 7671:2001? but all work was ok'ed and then covered up after first fix.
as for understanding the new changes in the 17th edition, that's why I'm here also, to clarify and make sure i don not 'fall flat on my face' by missing any important changes that apply to the suggested work i wish to carry out. i am not by any description a full time electrician but i am willing to read up before i remove a single screwdriver from my toolbox .
as for compliance,and notification of work i wish to carry out...i am not yet at that stage yet, i am testing the water to see if this work is within my understanding and skill level before i start,that is why a have come here....for some advise .
in response to chri5:
neither property was or will be done for commercial gain...I'm helping my sister out as she has had some astronomical quotes back for the job from quite a few companies and as we were willing to do all the donkey work e.g. pull down ceilings to make wiring easy,chase all walls and notch/drill any joists, all they had to do was wire to the pattress boxes we fitted and install a CB. it got quite high so we are looking at this route,not that i would wish to tar anyone with a brush so soon but alot of sparks in my area charge far too much and then moan they do not have any work.
yes i do know it is quite an involved job but it has also to be fair and realistically priced
in reply to mikhailfaradayski:
I'm looking out for 'a copy of the regs, OSG and a nice sparkies guide'

in a short reply to electronicsuk again:
i cant chase all my wires deep enough so they will be RCD protected and as for the outside sockets and lights,they will have their own RCBO's from the non-RCD side of the CU.

this i swiped from a gov site:

knobbiewilliams wrote:
Supplementary Bonding between metallic service and waste pipes and the earth connections of equipment is no longer required providing the main
bonding of services within the property is in place and the metallic pipework can be proved by testing to be continuous.
This means that the need for green and yellow cables in bathrooms is unlikely to be necessary.
can't find my link for this but will try to get back to you with this.

one registered spark without checking what supply was used just kicked the earth rod and told my sister that 'this is now not required'??

quote: 'As for the earth rod, that only comes into the equation if you have a TT supply. If you are TT, it would be worth asking your supplier if you can be converted to PME before you go any further with your planning. If you choose to remain on a TT supply, ALL circuits will need to be RCD protected whether you like it or not. '
i shall have to enquire!
ps. we will be fitting wall lights in most rooms so lights will need protecting.
once again, slag-off or praise is welcomed at this early stage before a single tool is removed from my toolbox and always read with an open mind, a thick skin a cup of hot coffee and a smile!

please point out any mistakes in my post as i am a noob at posting
hope i have gone over your points and explained myself better but this again is a late night post

 

[ban-all-sheds]

got a qualified spark to inspect,check and test with paperwork all work i carried out on my house,

So possibly the Inspection & Test section of the 3-section EIC (but probably just a PIR). In any event, unless the guy lied, no signed declaration from someone competent to make one that the design and construction were compliant.

not sure of the BS 7671:2001?

That's confusing, given that you said "I re-wired my own house to full regs"...

as for understanding the new changes in the 17th edition, that's why I'm here also, to clarify and make sure i don not 'fall flat on my face' by missing any important changes that apply to the suggested work i wish to carry out. i am not by any description a full time electrician but i am willing to read up before i remove a single screwdriver from my toolbox .
as for compliance,and notification of work i wish to carry out...i am not yet at that stage yet, i am testing the water to see if this work is within my understanding and skill level before i start,that is why a have come here....for some advise .

Basically you can't carry out a job of this magnitude by asking whatever random questions happen to occur to you. You've already shown that you have some dodgy misconceptions - what if you get something wrong because you have no idea your knowledge is wrong? What if you miss something because you simply have no idea it even exists, and just don't realise you don't know it?

The work is notifiable, and if your sister wants to end up with the required documentation for her property (and she really should want that) you aren't going to be able to ignore that fact.

There's no reason to think that you couldn't learn everything you need to, and do a perfectly good job, but you can't learn by asking unstructured questions and you can't learn as you go along, so if your sister waits for you to be ready then her house is going to look like this

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• knobbiewilliams
• 29 Nov 2009
• 1

for a lot longer than she will probably want.

You need to get an electrician to take complete charge of the job - she needs to make all the design decisions, obviously guided by your requirements etc, but she has to be the one to say which CUs will and will not comply with the regulations, she has to be the one to decide if you have a TT installation or not, and so on and so on.

You doing the donkey work is realistic, but only if she agrees, and only under her direct guidance and supervision, as she will have to sign a number of declarations to say that she did all of the work. You can be her unpaid labourer, but she has to be 100% in charge, and all of the questions you are asking here can only be answered by her.

 

[LiamPope]

But where's he gonna find this female spark?

 

[Steve]

I love it when ban uses "she" to refer to electricians. Its as if he's being paid by the equal rights commision (what a waste of money this is). I suppose he's got to fit in a reference to a black and indian electrician soon. And a couple of poles.

 

[ban-all-sheds]

No - I just like to ring the changes, recognising that not all electricians are male.

Your excuse for acting like an ignorant **** is what, exactly?

 

[electronicsuk]

Your excuse for acting like an ignorant **** is what, exactly?

Perhaps it was in jest?