Rcds Or Rcbos?

[FozzyTime]

Hi All Quick question

If all Power Circuits must have rcd protection

But all Circuits must have the own protection

Should we not always use RCBOs?

My understanding is that if there is a fault on the downstairs Cicuit it shouldent effect the upstairs one.

But if we choose to have a split load board they are both protected by one RCD

Looking for a bit of clarity on this conundrum.

Thanks

Mike

 

[adammid]

if you have a split load board downstairs lighting is protected by one rcd and upstairs lighting is protected by the second rcd.

 

[Apache]

In an ideal world you could put forward an argument for each circuit on its own RCBO. The issue is cost and if you quote a CU swap based on that then someone else comes in £150 cheaper....

Realistically can you remember the last time a RCD tripped in your house?

 

[SPECIAL LOCATION]

Hi All Quick question

If all Power Circuits must have rcd protection

But all Circuits must have the own protection

Should we not always use RCBOs?

My understanding is that if there is a fault on the downstairs Circuit it shouldn't effect the upstairs one.

But if we choose to have a split load board they are both protected by one RCD

Looking for a bit of clarity on this conundrum.

Thanks

Mike

1. All power circuits do NOT have to have RCD protection....

Unless you can point to a regulation that says otherwise!

2. It is not very complicated to design an installation with suitable discrimination to minimise the inconvenience in the event of a single fault.

3. Not all faults involve earth leakage or tripping of RCD's

4. Not all RCBO's are double pole...... therefore may not give the level of protection required.

5. In an ideal world with costs being no barriers and customer being prepared to pay for the "best solution" full individual RCD/RCBO protection would be advantageous...

Our Sponsor SBS has some very good solutions!

Guinness

 

[Theorysparky]

split load board only 1 rcd cover some ccts and the others are not protected

dual board has 2 rcds where all ccts are protected and are split accordingly

the no protected side of a split load board could have rcbo's fitted to give full protection

most sparkies would use an rcbo board these days by choice if the customer was willing to pay the extra but we can lose the extra cost by hiking the other prices up

 

[SBS Dave]

Thanks Canoeboy and Special Location for the plug!!

Let's take a 17th Edition Split Board, say with 8 circuits. Cost ??   £50.00 + VAT ??

My 10-way Standard RCBO board with 8 RCBOs and 2 x Blank strips to make it up to £100.00.

Less 10% discount = £90.00 + £6.00 postage =  £96.00 + VAT.

Not £150 difference but £46.00. Trying to make the 17th Edition DB fit into the existing space, plus extending circuit conductors could add another hour to his job.

If you need to compete with the "other guy", offer your customer the 17th Edition solution at the same price as his and then offer the state of the art nuisance trip free alternative for just 50 quid more. It should be a fairly easy sell.

SBS Dave

 

[sprocketflup]

I had the pleasure of connecting up some of your RCBOs today SBS dave, very nice mate, top marks to ya

 

[msb2003]

Hi All Quick question

If all Power Circuits must have rcd protection

But all Circuits must have the own protection

Should we not always use RCBOs?

My understanding is that if there is a fault on the downstairs Cicuit it shouldent effect the upstairs one.

But if we choose to have a split load board they are both protected by one RCD

Looking for a bit of clarity on this conundrum.

Thanks

Mike

Regulation 314.2 (often ignored!) states "Separate circuits shall be provided for parts of the installation which need to be separately controlled, in such a way that those circuits are not affected by the failure of other circuits" therefore a split board where 1 or 2 RCD`s cover numerous Circuit Breakers isn`t strictly compliant.The NICEIC and ECA are aware of this but generally turn a blind eye from what I have seen.

Your opening statement of all power circuits needing RCD protection is a misinterpretation of the regulations that state all socket outlets up to 20A need to be RCD protected. Secondly unless you provide mechanical protection for cables in walls less than 50mm deep you also need RCD protection. This means most switch drop and sockets require RCD`s so generally, domestically all circuits are protected. By spliting the installation, mixing upstairs and downstairs circuits you miminise the inconvienience if one RCD operates, lights or power will still work when the other one does not.

I hope this helps clarify things for you

 

[Sidewinder]

msb,

You should check the wording of the regs that you are referring to with regard to socket outlets up to 20A carefully again and understand what it, actually, says.

Also, you should consider your wording carefully, because not all buried cables require RCD protection even if they are less than 50mm deep, and not given additional mechanical protection.

Please come back to us then with your further ideas...

 

[steptoe]

msb,

You should check the wording of the regs that you are referring to with regard to socket outlets up to 20A carefully again and understand what it, actually, says.

Also, you should consider your wording carefully, because not all buried cables require RCD protection even if they are less than 50mm deep, and not given additional mechanical protection.

Please come back to us then with your further ideas...

sidewinder,

in general, with most domestics, and the knowledge of the people installing them,

and their abilities,

I would side with msb purely on the fact that it was a generalisation he pointed out.

still doesnt make a split RCD board compliant though, as pointed out by him also.

 

[Sidewinder]

Who said domestic?

I can't see Fozzy mentioning domestic anywhere?

There is no specific mention of limiting this to domestic, hence my point.

 

[steptoe]

yes, you are correct, fozzy never mentioned domestic,

msb did, so perhaps an assumption on his part, and mine too,  :|

 

[msb2003]

msb,

You should check the wording of the regs that you are referring to with regard to socket outlets up to 20A carefully again and understand what it, actually, says.

Also, you should consider your wording carefully, because not all buried cables require RCD protection even if they are less than 50mm deep, and not given additional mechanical protection.

Please come back to us then with your further ideas...

Ok, if sockets are undersupervision or clearly labeled for use of a specific piece of equipment you are correct they do not need to be RCD protected but instead of your smart arse remark, why not share your superior knowledge in the first place?!

Fozzy, I hope my comments did not confuse you

PS thanks Steptoe for the vote of confidence :Salute

 

[steptoe]

msb,

you are welcome,

but,

what we need to remember is ,

this interweb thingie is read my a LOT of folks, and some may not read the whole thread,

just the 'relevant' post as they see it.

 

[Sidewinder]

msb,

Why should I "share" anything with you when you come with an attitude like that?

I suggested you actually "read" & "understand" the wording and come back to us.

This would be the same answer I would give when teaching regs or I&T, look at your statement, look at your reference source, and come back again with your ideas and explain them in direct relation to the regs you are quoting, along with your opinion on them.

There is no point in just giving answers, people don't learn that way, well, most don't, & I don't teach that way.

If you want to be an arse, then the thread will stop here, trust me the mods will be down on it like a tonne of bricks.

If you want to come back with further suggestions & ideas, then this can be further discussed and debated as required.

Else I think there may well be a mod invasion, with no Lambrettas in sight!

 

[Doc Hudson]

Hi All Quick question

If all Power Circuits must have rcd protection

But all Circuits must have the own protection

Should we not always use RCBOs?

My understanding is that if there is a fault on the downstairs Cicuit it shouldent effect the upstairs one.

But if we choose to have a split load board they are both protected by one RCD

Looking for a bit of clarity on this conundrum.

Thanks

Mike

In light of some earlier posts and for the benefit of all members reading this thread, I would point out that FozzyTime does not specifically mention Domestic work in his opening post. But reading the whole post (copied above) he does mention upstairs and downstairs circuits. Which as a general rule implies it is probably a question relating to domestic installation. I think most competent electricians on the forum would agree that most domestic circuits in a typical property, with T&E cables buried and sockets used by unskilled persons would in an ideal world, benefit from a CU solution with double pole RCBO's such as those provided by our forum sponsor SBS Dave, whilst also recognising that most high integrity CU's with two or more RCD's protecting groups of circuits, suitably split, is also a solution for other jobs where full RCBO protection is not economically feasible. With this in mind lets also keep our discussions polite and respectful. Thank you

Doc H.

 

[msb2003]

Sidewinder

references for my previous coments, I did assume a domestic installation as upstairs and downstairs mentioned (possibly as mistake to make the assumption)

Regulation 314.2- Separate circuits shall be provided for parts of the installation which need to be separately controlled, in such a way that those circuits are not affected by the failure of other circuits. and due account shall be taken of the consequences of the operation of any single protective device.

hence my comment that multiple circuit breakers fed from one RCD is not strictly compliant,

Regulation 411.3.3- In a.c. systems, additional protection by means of an RCD in accordance with Regulation 415.1 shall be provided for:
(i) socket-outlets with a rated current not exceeding 20 A that are for use by ordinary persons and are intended for general use, and
(ii) mobile equipment with a current rating not exceeding 32 A lor use outdoors.

An exception to (i) is permitted for:

(a) socket-outlets tor use under the supervision of' skilled or instructed persons. or
(b) a specific labelled or otherwise suitably identified socket-outlet provided tor connection of a particular item of' equipment.

hence my comments in my second post about supervision and labelling
 

Regulations 522.6.100 and 101 (assuming we are installing in the UK as specific for here, hence the 101 numbering)-

522.6.100 A cable installed under a floor or above a ceiling shall be run in such a position that it is not liable to be damaged by contact with the floor or the ceiling or their fixings. A cable passing through a joist within a floor or ceiling construction or through a ceiling support (e.g. under floorboards), shall:
(i) be at least 50 mm measured vertically from the top or bottom as appropriate of the joist or batten, or
(ii) incorporate an earthed metallic covering which complies with the requirements of these Regulations for a protective conductor of the circuit concerned, the cable complying with BS 5467, BS 6724, BS 7846, BS EN 60702-1 or BS 8436. or
(iii) be enclosed in earthed conduit complying with BS EN 61386-21 and satisfying the requirements of these Regulations for a protective conductor. or
(iv) be enclosed in earthed trunking or ducting complying with BS EN 50085-2-1 and satisfying the requirements of these Regulations for a protective conductor, or
(v) be mechanically protected against damage sufficient to prevent penetration of the cable by nails, screws and the like, or
(vi) form part of a SEL V or PEL V circuit meeting the requirements of Regulation 414.4.

522.6.101 A cable concealed in a wall or partition at a depth of less than 50 mm from a surface of the wall or partition shall:
(i) incorporate an earthed metallic covering which complies with the requirements of these Regulations for a protective conductor of the circuit concerned. the cable complying with BS 5467, BS 6724, BS 7846, BS EN 60702-1 or BS 8436, or
(ii) be enclosed in earthed conduit complying with BS EN 61386-21 and satisfying the requirements of these Regulations for a protective conductor. or
(iii) be enclosed in earthed trunking or ducting complying with BS EN 50085-2-1 and satisfying the requirements of these Regulations for a protective conductor. or
(iv) be mechanically protected against damage sufficient to prevent penetration of the cable by nails, screws and the like, or

(v) be installed in a zone within 150 rnrn from the top of the wall or partition or within 150 rnrn of an angle formed by two adjoining walls or partitions. Where the cable is connected to a point, accessory or switchgear on any surface of the wall or partition, the cable may be installed in a zone either horizontally or vertically, to the point, accessory or switchgear. Where the location of the accessory, point or switchgear can be determined from the reverse side, a zone formed on one side of a wall of 100 rnrn thickness or less or partition of 100 mm thickness or less extends to the reverse side, or
(vi) form part ofa SELV or PELV circuit meeting the requirements of Regulation 414.4.

522.6.102 Where Regulation 522.6.101 applies and the installation is not intended to be under the supervision of a skilled or. instructed person, a cable installed in accordance with Regulation 522.6. 101 (v), and not also complying with Regulation 522.6.101(i), (ii), (iii) or (iv), shall be provided with additional protection by means of an RCD having the characteristics specified in Regulation 415.1.1.

These are the regulations I refer to when I say a cable requires RCD protection if less than 50mm deep in a wall if not suitably protected.

I would appreciate your views as to why this is incorrect as I would teach by explaining mistakes after students had made an error not simply tell them they are wrong.

Mods, I appologise for my previous comments but found the reply to my post inappropriate for those seeking help

 

[ParkySparky]

Don't worry msb you'll get used to the constant tongue lashing on here if you do not use 100% correct wording and terminology of the regs and justify everything you say yo within an inch of your life!

Ask a question if you dare!!!

Very knowledgable people on here and are very quick to ram something not quite worded correctly back down your throat before you can say anything!!!

 

[steptoe]

and dont ever dare say

MAIN EARTH

:coat

 

[kerching]

I would never ram anything down anyones throat M'lud

i am probably the worst offender at using the wrong terminology....as i have been using the CORRECT terminology for 40 plus years.

i work on my own so it does not really cause me a great loss of sleep.   At my age it is F hard to change.... Phrases to avoid can include, but are not limited to

fuse board

green sleeve

earth wire

main earth

megger it

knob end 

dogs c0ck

ring main

NORWEB

MANWEB

Meter man

qualifications

apprenticeship

and a couple of others