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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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    Alan Capon:




    Martynduerden:

    But what about the enclosure itself Alan? Clearly the devices have a certified kA rating and that is fairly easy to ascertain but the enclosures kA rating is manufacturer certified subject to use of their prescribed devices . . . 




    That is where the entertainment begins. In theory an mcb used at or below its rated fault current will trip on a fault as everyone expects every time. If the mcb is used above it’s rated current, it may trip correctly, or it may fail catastrophically. The idea of the conditional “rated assembly” is that if the device fails attempting to trip, the enclosure will contain all the bits, including the explosion until the upstream protective device (the supplier’s cutout for example) clears the fault. If the type-tested assembly fails, then the manufacturer may be liable. If they can then prove the presence of another manufacturer’s device or a device of theirs that was not included in the testing was fitted, then it is likely they have no liability. 


    My reason for not giving a definite response, is that a catastrophic failure of a type-tested assembly would have to be examined in a court of law for an absolute judgement. 


    Regards,


    Alan. 


     




    That is my reading too Alan, although you have also prompted the question, Will a manufacturer honour their individual device kA ratings where that device is outside its intended location? 


    Cheers 


    Martyn 

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    Alan Capon:




    Martynduerden:

    But what about the enclosure itself Alan? Clearly the devices have a certified kA rating and that is fairly easy to ascertain but the enclosures kA rating is manufacturer certified subject to use of their prescribed devices . . . 




    That is where the entertainment begins. In theory an mcb used at or below its rated fault current will trip on a fault as everyone expects every time. If the mcb is used above it’s rated current, it may trip correctly, or it may fail catastrophically. The idea of the conditional “rated assembly” is that if the device fails attempting to trip, the enclosure will contain all the bits, including the explosion until the upstream protective device (the supplier’s cutout for example) clears the fault. If the type-tested assembly fails, then the manufacturer may be liable. If they can then prove the presence of another manufacturer’s device or a device of theirs that was not included in the testing was fitted, then it is likely they have no liability. 


    My reason for not giving a definite response, is that a catastrophic failure of a type-tested assembly would have to be examined in a court of law for an absolute judgement. 


    Regards,


    Alan. 


     




    That is my reading too Alan, although you have also prompted the question, Will a manufacturer honour their individual device kA ratings where that device is outside its intended location? 


    Cheers 


    Martyn 

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