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Topic Title: Mixing mcb's in CU
Topic Summary: different makes of mcb together, what code?
Created On: 19 August 2009 08:20 AM
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 19 August 2009 08:20 AM
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mark2spark

Posts: 1444
Joined: 15 November 2006

Hi Guys,

This topic has been covered before. The problem is that each CU board manufactuer doesn't allow for other makes of mcb to be fitted within their enclosure. There is a BS refernce number somewhere.

I was just wondering what code you guys would give, on a PIR, if you came across, say, a contactum board, with a mixture of contactum, Mk, and Legrand mcb's in the board?
It's not a 1 or a 3, hardly a 4. That leaves 2, which is a fail? Really?

(The thing is, each of these mcb's conform with 60898 so why can't a board be fitted with any make providing the 60898 legend is clear?)(Customers question)

Cheers, I'm off out to work now so will check back in tonight

Mark

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I am prone to talking complete bol***ks at times, please accept my apologies in advance.
 19 August 2009 08:39 AM
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davezawadi

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It should not be coded and is not a defect. The problem is the test regime for board designs requires testing at fault current, and it simply isn't possible to test all combinations of manufacturers breakers. So to cover themselves they all say "only use our make". I can think of no reason why any make which fits properly and has tight connections will not be satisfactory. The usual comments about temperature rise etc. clearly are not relevant because 60698 specifies maxima which must be OK anyway.

Either the breaker works or it doesn't, and all must clear their fault rating without coming apart, so the outside enclosure has nothing to do with this discussion. What happens if subjected to extreme faults is not your problem, and cannot happen if the rating is correct in the first place, for example 6kA or 10kA. There is always the REC fuse if the fault level became very high, for example if a HV line fell onto an overhead supply. Not much would probably survive intact anyway!

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David
CEng etc, don't ask, its a result not a question!
 19 August 2009 11:19 AM
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ACKS72

Posts: 241
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Originally posted by: davezawadi

It should not be coded and is not a defect. !


510.2 Every item of equipment shall be selected and erected so as to allow compliance with the regulations
stated in this chapter and the relevant regulations in other parts ofBS 7671 and shall take account of manufacturers' instructions.

Acks
 19 August 2009 11:28 AM
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davebarman

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We use MK, Merlin Gerin and Square D which effectively are the same MCB, just take out the push fit connector on the SD.

Although if you had to make a claim against a faulty item fitted into someone else's enclosure or dist.board then like insurance's any old excuse to not pay out. Ah well never mind V is nearly here.

Regards

Dave

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 19 August 2009 02:13 PM
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AJJewsbury

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At an outside possibility it would be a contravention of 530.3.4 which requires protective devices 'specified by the manufacturer' - but only if the PFC was so high that there was reliance on annexe ZA of BS EN 60439-3 - i.e. if PFC not only exceeded the rating of the MCB alone, but the MCB with backup protection of a supply side fuse too - probably very unlikely in a domestic situation, but theoretically possible.

- Andy.
 19 August 2009 02:21 PM
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perspicacious

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Naturally the installer issued an EIC for his work so it would tend to reside with him but if there were not an EIC available, what observation and associated recommendation would you allocate for this, fairly common departure?

Regards

BOD
 19 August 2009 02:30 PM
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AJJewsbury

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If the fault current was high enough to have to invoke annexe ZA (>> 6kA) then most of the T&E CPCs are probably too small as well, so probably code 4 for the mixed manufacturer parts and a 2 for the CPCs. But as I say, unlikely in a domestic.

If the fault current was lower, then not a direct contravention of BS 7671 (which is what the PIR is meant to be judged against) so no code IMO.

- Andy.
 19 August 2009 02:49 PM
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davezawadi

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510.2 Every item of equipment shall be selected and erected so as to allow compliance with the regulations stated in this chapter and the relevant regulations in other parts of BS7671, and shall take account of manufacturers' instructions (even if in contradiction of BS7671 and EN60898 etc.)? (My comment!)

Is this the instruction that the installation should only be used by competent persons, or possibly not powered up until approved by some third party? Unless the instruction is fixed to the item in question and in clear view, it would have questionable value. How do you know what instruction was on a manufacturers web site in 1986, or even included in the original packaging (if any)? Such "get out" clauses should be banned.

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David
CEng etc, don't ask, its a result not a question!
 19 August 2009 02:55 PM
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ACKS72

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Naturally the installer issued an EIC for his work so it would tend to reside with him but if there were not an EIC available,
- code 3 requires further investigation as to where the EIC is.

With regards to the wrong manufacturers MCB in the board - if i were doing the report it would be a code 2 and either replace with correct MCB (if available) or replace consumer unit for £60+labour OR depending on my contract with the client a code 3

Acks
 19 August 2009 07:51 PM
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chrisselby

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I would like to be at the garage when you take your van in for an mot and they fail it because you have fitted a pattern part insted of a genuine part.

this is the same thing. just because the same manufacturer has not been used when fitting a new mcb into a db then you cannot code it.

if it fits without modification, to any part makes no gaps or you dont need to modify the busbar then why not use a different brand?

after all it is just a plastic box with a rail to fit in the mcbs.
 19 August 2009 07:51 PM
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chrisselby

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I would like to be at the garage when you take your van in for an mot and they fail it because you have fitted a pattern part insted of a genuine part.

this is the same thing. just because the same manufacturer has not been used when fitting a new mcb into a db then you cannot code it.

if it fits without modification, to any part makes no gaps or you dont need to modify the busbar then why not use a different brand?

after all it is just a plastic box with a rail to fit in the mcbs.
 19 August 2009 09:09 PM
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kaichung

Posts: 369
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Correct me if I am wrong..

If there is a clearly identifiable BS88 etc. switch fuse immediately upstream of the consumer unit affected, with adequate breaking capacity, does it matter what make the breakers are, provided they fit properly and securely, and are of the correct type and rating for the intended loads?

Surely the BS88 etc. switch fuse will provide the correct breaking capacity in this instance?
 19 August 2009 09:47 PM
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Testit

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My view is that if each mcb is to the same standard as the original units mcbs then they should be interchangeable... if not then a complaint should be made to british standards for mcbs made to a standard they are non compliant with...

Corporate exclusivity statements such as only tested with our equipment and others will void any warranty, should be taken to task as the parts are made to the same standard and should really state tested with MCBs to whatever relevant standard they are employing.... if not then the BS standard is just a mockery... The only difference sometimes encountered I find is width so they should be of comparable dimensions and busbar allignment...

You could put a code 4 (corrective) if you want to state its non compliant with BS7671 from the statements above... My easycert also has a code 4 (urgent) specified.....

I have no qualms abuot sticking in some comparable MCBs in a unit..... It looks nicer if they are the same make however and I don't see a reason for using other makes other than on th eodd occasion a 3rd off th eprice of an RCBO when they were all rather expensive was an attractive option...

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Experience can sometimes show that cost prevails over quality and safety, such little self-value that people hold.
 19 August 2009 10:17 PM
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alancapon

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I agree with Andy's earlier comment. If the PFC is higher than the rating of the mcbs, then you are relying on annexe ZA of BS EN 60439-3. This gives the consumer unit a conditional rating of 16kA provided that the consumer unit has been type tested as an assembly and that the unit is protected by a fuse to BS1361 type 2 or equivalent. If the mcbs are from different manufacturers, then the assembly (as installed) will not have been type tested together, and the 16kA conditional rating cannot be applied.


Regards,

Alan.
 19 August 2009 11:29 PM
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Testit

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If the mcbs are from different manufacturers, then the assembly (as installed) will not have been type tested together, and the 16kA conditional rating cannot be applied.


The only point I will argue against that is that I buy the MCBs seperately and they are made to thier own BS standard.. namely BS EN 60898... This is a BS standard and the components tested as an assembly are the assembly with components to BS EN 60898... not say Hager MCBs, or MK mcbs, but MCBs to BS EN 60898....

I would have to argue that such an argument is not valid.... I'm sure the manufacturers who want their parts used will agree with everytone who disagrees with me however...

-------------------------
Online Services - http://propertydevelopment.org.uk

Experience can sometimes show that cost prevails over quality and safety, such little self-value that people hold.
 19 August 2009 11:40 PM
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alancapon

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If you buy an mcb made to BSEN60898, and it has a PFC rating of 6kA, then it can only be used on an installation with a PFC of less than 6kA at the point where it is fitted. If the installation's PFC is higher at that point, then you will need to use annexe ZA of BS EN 60439-3, which gives a conditional PFC of 16kA (even for a 2kA rated BS3036 fuse).


Regards,

Alan.
 19 August 2009 11:47 PM
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deleted_1_kevin432

Posts: 151
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I agree with chrisselby, if they are of an identical fit and rating and provide the same protection then i wouldnt have a problem with them.

At the end of the day all manufacturers are only going to recommend their own products - its the same with shampoo they only recommend their own brand of conditioner, its how branding works.
 20 August 2009 12:46 AM
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Testit

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Originally posted by: alancapon

If you buy an mcb made to BSEN60898, and it has a PFC rating of 6kA, then it can only be used on an installation with a PFC of less than 6kA at the point where it is fitted. If the installation's PFC is higher at that point, then you will need to use annexe ZA of BS EN 60439-3, which gives a conditional PFC of 16kA (even for a 2kA rated BS3036 fuse).

Regards,
Alan.


Agreed...

Going back to the argument of mixing makes of MCBs in a BS EN 60439-3 unit... my earlier comment about manufacturers agreeing was a little scinical and not explained adequately....

A manufacturer will state that use of another manufacturers parts will void their liability/guarantee. If you examine this more closely it will become apparent that if you are a manufacturer you cannot be responsible for the standards or manufacturing process of another manufacturer.... So if you don't put in the same make of MCB as the manufacturer of the unit to BS EN 60439-3 then they will state they cannot be held responsible for the rating of the unit as they cannot account for the other manufacturers parts....

This is a logical argument on the part of the manufacturer in relation to their liabilities.... however essentially it is saying that Hager cannot account for the manufacturing processes or standards of MK for instance.... however the politics of a manufacturers liabilities do not change the issue that the parts are to the same BS EN standards and will therefore perform in the same way... A unit to BS EN 60439-3 with as an example Hager and MK MCBs mixed will still have the same rating, unless either Hager or MK are cutting corners in some way...either way you are no safer using Hager or MK boards if their parts are not up to the standards they stipulate they are... so it is clearly arguable that MCBs if having the same dimensions and BS standards can be interchanged without effecting the rating of the unit.... the liabilities of the manufacturer is a political argument as to who exactly would be responsible.. Likely the maker of the unit to BS EN 60439-3 purchased..

Edit: So I think my argument about being able to interchange MCBs to the same standard and dimensions would hold in court somehow..

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Experience can sometimes show that cost prevails over quality and safety, such little self-value that people hold.
 20 August 2009 02:55 AM
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spinlondon

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I do know from experience that manufacturers will inform you that their MCBs will be alright to use in another manufacturer's enclosure.
 20 August 2009 07:12 AM
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normcall

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And of course, all manufacturers make their own - not either making for other manufacturers or 'buying' them in.
It used to be so easy with wylex or MEM 3036 fuses!

-------------------------
Norman
IET » Wiring and the regulations » Mixing mcb's in CU

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