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EICR C3 mixed manufacturer breakers

Martyn
I know this will have been discussed in the past but we are on Amd 1 of the 18th now so I thought I would renew it.


The Best practice guides list mixed manufacturer breakers in a consumer unit or distribution board as a C3.


As far as I am aware Bs7671 does not have a Reg on it beyond manufacturers instructions and given EICR's are based on this standard perhaps it is justified on that basis.


Most on here will be familiar with the 16kA 'rule' in BSEN61439 Annex ZB or its predecessor BSEN60439 Annex ZA


I avoid C3's like the plague because they give all the wrong signals to a client and clearly by definition are for things which are a breach of the regs, I'm not too keen on the insurance risk of a C3 either.


My question here would be what fault rating can one apply to an enclosure where there are mixed breakers given a manufacturer will only have certified their equipment with their devices?


Enjoy!


Martyn
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    I would argue that a fault has already occured by dint of the assembly having insufficient fault rating for the installation.




    Err no. The fault has only occurred when you are called out to take a look at the smoking remains and twisted metal hanging off the wall... 

    It could however certainly be C2 - if the next big fault that comes along that should operate ADS, instead blows the thing to bits.

    So single fault to danger, not already dangerous.




    Like others I can count on the fingers of one foot the no. of times I have ever seen an MCB fail catastrophically  in anything other than film taken during a lab test set up.


    The Americans estimate the energy density  from arc events  using these formulae  . I am aware that in the UK we do not normally, but in the US they calculate a rating in joules per cm2 for exposure, and then assume the energy spreads out from the source, to get a safety distance.

    However, work beckons,  and I'm having "fun" with the formulae in the forum software , so rather than cock it up I will come back and do it properly in another post, probably tonight.


    However, even for an open arc, at the risk of spoiling the conclusion, so long as the arc is cut suitably short by a suitable up stream fuse, you do not need much weight in the way of containment until >>10kA  at mains voltages (less for an arc partly dissipated in tearing up the case of a breaker.) You could probably make a safe CU out of plastic.  ?


    Given how most modern  enclosures are steel, and would stop the max legal  air gun pellet of 12 joules with an impact area of less than 1cm2  it is quite informative to compare that to yjr  incident energy from the un-restrained arc flash in a typical box.  In general a bigger box has an easier time, as the energy has space to be spread more thinly.

     


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    I was referring to 7671 & 61439 in regards to type tested assembly, 60898 is just a device standard isn't it?


    It may or may not be ' immediately dangerous ' my point is I cannot know it is not because it has not been tested of approved in such scenario.


    MOT's have a list of defined faults and actions we do not, when you get your MOT certificate (or not) you get a specific number such as (1.1.c.1d)  for example.


    I don't come across many EICR's that list the actual regulation, I personally do it mainly because it raises less nonsense when the installation does not pass.


    We cant control the nefarious actions of others and I wholeheartedly agree that generally EICR's are naff, usually a satisfactory is a good indicator that it it anything but satisfactory to current regs.


    I did not think for a moment it was personal Dave ?
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    Um, I am rather confused by the reply, what are the two "standards"? EN60908 says nothing about all items selected must come from a single manufacturer, and in some cases cannot. A code 1 specifically says the installation is immediately dangerous to users. How is a CPD failure by disintegration immediately dangerous to anyone, it breaks the circuit by definition. It may cause other problems but you are now in "what if" territory, and you need to give an example of this happening under the discussed conditions. I am not getting at you personally, but EICRs depend on accurate assessment of risks, just like an MOT. It is part of the profession to do this without fear or favour, and I would uphold this requirement probably above all others. You and I both know that the EICR is often not done properly, and is often used as a pressure for more work. For landlords it is particularly important that it is both fair and accurate. That is why it should be the same for all sectors of rented property. The danger of a different make of equipment being used is a million miles from the real danger areas, like lack of Earth or bare wires.
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    davezawadi:

    Reasonable codes are a requirement for a "qualified" inspector, with "experience" of risk at the correct level. Anything else is simply fraudulent for presumably pecuniary reasons against the unsuspecting and unknowing customer. If I came across an EICR with this coded as C1 I would contact the certifying body, because it is totally unreasonable.


    Only 1 answer so far to my questions, negative.






    Hi Dave,


    I believe rightly or wrongly that I could easily defend this gripping the bar if I needed to,.


    I guess my first argument might be something like , 'I'm not sufficiently technically competent to override two standards aimed soley at the protection of people nor am I insured to do so"


    As a rule of thumb I never do both an EICR and the associated remedial works, I generally use an external genius for such things.


    Cheers


    Martyn

     

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    AJJewsbury:




    I avoid C3's like the plague





    Personally this always gets a C1 from me for the simple reason that PFC will always be greater than zero kA and the only rating I can apply to the enclosures and devices is zero kA



    I'm a little puzzled... for me:


    C1 = actual danger present now (with no additional faults) - e.g. bare line conductors, easily touched.

    C2 = danger would be present if a single fault occurred in the future - e.g. broken c.p.c. or Zs too high.

    C3 = danger would be present if two faults occurred (and the current regulations provide some protection under those circumstances) - e.g. lack of additional protection.

    no code (old code 4) for things that although don't comply with the current regulations pose no additional hazard to users of the installation - e.g. old (or incorrect) core colour codes.


    and then following the same weightings as it were for hazards other than shock. So say for example, lack of overload protection but no evidence that anything actually has ever been overloaded might be a C2, evidence that insulation had been melting a C1.


    So for me a CU with an inadequate fault breaking capacity would be perfectly safe under the current conditions - any problems would only arise on the future occurrence of a future fault - so that couldn't be higher than a C2 for me.


    Likewise C3 seem ideal to me for things like lack of 30mA RCD protection to internal sockets etc.


      - Andy.

     




     

    I would argue that a fault has already occured by dint of the assembly having insufficient fault rating for the installation.


    This question was primarily raised on the basis of commercial buildings and 3 phase supplied boards, I cant say that I have come across a domestic at anything like 10kA that said, as soon as you mix and match you have left the relative comfort of the manufacturers certificate and liability.


    On your last point, How long has 30mA RCD protection been an absolute requirement (In new installations) for internal sockets?


    Given it is an absolute requirement for new installations, why would a report on a an existing installation when compared to the current regulations result in the lowest of all codes?


    I see RCD's being removed from spec on new purely for this reason, 'it is only a C3 so I will save a few quid and wont bother specifying them' is the mantra I hear.
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    Reasonable codes are a requirement for a "qualified" inspector, with "experience" of risk at the correct level. Anything else is simply fraudulent for presumably pecuniary reasons against the unsuspecting and unknowing customer. If I came across an EICR with this coded as C1 I would contact the certifying body, because it is totally unreasonable.


    Only 1 answer so far to my questions, negative.
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    Andy, Hmmm. Good! I was wondering who would spot that deliberate mistake of mine confusing a C3 with an old code 4 (Captain Mannering defence retort).

    Think Dave Z did likewise on the resistor and transmitter Q too with me not realising the current sink (source) scenario too.


    I`m off to the corner to slap myself
  • 0

    I avoid C3's like the plague





    Personally this always gets a C1 from me for the simple reason that PFC will always be greater than zero kA and the only rating I can apply to the enclosures and devices is zero kA



    I'm a little puzzled... for me:


    C1 = actual danger present now (with no additional faults) - e.g. bare line conductors, easily touched.

    C2 = danger would be present if a single fault ocured in the future - e.g. broken c.p.c. or Zs too high.

    C3 = danger would be present if two faults occurred (and the current regulations provide some protection under those circumstances) - e.g. lack of additional protection.

    no code (old code 4) for things that although don't comply with the current regulations pose no additional hazard to users of the installation - e.g. old (or incorrect) core colour codes.


    and then following the same weightings as it were for hazards other than shock. So say for example, lack of overload protection but no evidence that anything actually has ever been overloaded might be a C2, evidence that insulation had been melting a C1.


    So for me a CU with an inadequate fault breaking capacity would be perfectly safe under the current conditions - any problems would only arise on the future occurance of a future fault - so that couldn't be higher than a C2 for me.


    Likewise C3 seem ideal to me for things like lack of 30mA RCD protection to internal sockets etc.


      - Andy.
  • 0
    Some interesting points raised.

    ebee, the points you mention about hotspots, ventilation, magnetism etc. Surely these issues (if they truly are issues) would be ironed out in order to provide conformity of the EN 60898 standard. In terms of spacings, MCB form factors are pretty much the same now, as in they sit side by side at the same distance regardless of manufacturer.


    Dave, I have only ever come across a no-reset scenario a few times. I have come across more main switches and RCDs with burnt terminals due to incorrect tightening rather then mcbs which have been atomised by catastrophic failure. Similarly, I have had one or two 10KA to 16KA PSCC measurements in domestic settings but they are the exception rather then the rule. The worst example of a Big Bang I have seen was in a 3 ph board where a sub contractor had connected phase to phase due to an old/new colours mix-up, but the disaster was contained safely when energised.


    You  raise a good point and ever present thorn in the side of many contractors, namely that of product life cycle and built-in obsolescence.

    Take the old Square D Q and KQ stuff, a bit like the old Federal stablock arrangement for the live side connections.

    Get a quote for a type B RCBO and then get the defibrilator on stand by!

    Apparently, manufacturers only have a duty to support a product for 10 years after it has been discontinued. They can stop making it after 5 years.

    You can still get one but it will only be made to order and not be off the shelf. This has resulted in whole DBs having to changed for no good reason other than the unavailability of components, and/or the outrageous costs of purchasing them.

    Highly wasteful and utterly mad in this anti waste woke climate change world we live in!.


    Sometimes - and I think that this applies across the board in today's society whatever the subject, there is an over-willingness to accept and not to question what we are told by 'experts'. I blame this on critical thinking skills no longer being taught in our educational institutions at all levels, and the comparative lack of students taking STEM subjects, but that is another argument!

    I don't know about you guys, but I was taught to question everything I was told, to gather evidence and then to make up my own mind.

    There are far too many out there who would have us still believe in fairies if we allowed them to get away with it - mktg men and lawyers being the worst examples!
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    In principle I am much more relaxed about this than may show above. Lets do a quick test. How many of you have ever seen a 60898 breaker which has physically failed in a domestic installation (exploded burnt up due to gross overload etc, not just failed)? How many have found domestic installations with a PSSC of more than say 10kA? How many have found the above where the case has not enclosed the results (plastic or metal)?


    The whole discussion of type testing is not quite as described above, because all the breakers must be made to EN 60898, which if this appeared in court would not be the case. The point of standards is that all items are interchangable in characteristics, so the manufacturer would have to explain non-interchangability of his product which would be very difficult. The type testing part is for the assembly of products, which in many cases will not have been tested as a complete assembly anyway, just a "representative" sample which muddies the waters still further. I can see exactly why manufacturers don't like products to the same standard to be mixed, but if they cannot be why have the "standard" at all as any design which is type tested is surely acceptable?


    This is not at all a simple case, and proving liability would be a nightmare, and anyway I have never heard of a manufacturer being taken to court for this kind of liability, or more particularly an installer. There is a further point, I am sure that a number of you have tried to obtain spare parts for assemblies which have been "discontinued" by manufacturers. Are you really suggesting that the entire assembly now needs to be scrapped? Consider your car or van (type tested) needs a part. Are after market non OEM parts safe to fit, say a different make of tyres, or wheel bearings? Now what do you think, an MOT fail?


    I rest my case M'Lud.

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