EICR C3 mixed manufacturer breakers

That is a good question. I would expect so, but a manufacturer may have other ideas! 


Regards,


Alan.

or more.

Given that a (say) 6kA breaker is guaranteed to break a 6kA fault and be reset.

During type approval, there is a test that requires the operation of the breaker to be verified again after breaking the full  fault current at least once.

If operated repeatedly, it must break the fault safely each time after it has been reset, but does not have to reset.- so it has to fail to a safe state where it cannot be reset.

  During all the testing up to that point the presence or absence of a case around it is in is cosmetic, and does not affect the ability to operate.

It is however allowed to fail at the containment at higher fault currents - and that  is when qualifying the whole assembly comes in, as the outer box may contain the flames and flying bits, so the rating for the breaker in the box, is higher than for the breaker 'bare'. Also at this point the glow wire tests start to matter as when one breaker blows up, you do not want the neighbours catching fire.


There are a few type approval test reports on the web, that give a flavour of typical results.

random example 

missed the edit window...

A better example.

Interestingly, WISKA also state that the enclosures I refer to have passed the 'glow test' too.

Personally, when it comes to a high energy disintegration of an overloaded mcb, I would reckon that all enclosures, be they of metal or plastic construction, are built to the same standard in terms of their ability to withstand a violent discharge and to contain the fall-out.

Mcbs are now all pretty much made to BSEN 60898 so should have that commonality too,

A cynic might suspect that the manufacturers are just doing what manufacturers do - protecting their revenue streams by utilising a measure which includes some dubious pseudo-scientific reasoning behind it.

When it comes down to the hard science, exactly what is it that may cause a catastrophic failure if 2 mcbs from different makers are sitting happily side by side in an enclosure?

Let us say for the sake of the exercise, that both mcbs have the same form factor, that the top and bottom terminal spacings are identical and that the busbar is not deformed during tightening.

What's to go wrong?

Just exactly how can a mcb from maker A undermine an enclosure and the other mcb from Maker B when they are all fitted together?

I would think that each manufacturer would be happy to have the same form of own breakers in adjoining spaces particularly with regards to hotspots and lines of magnetism and therefore ventilation. Thereby affecting safe ratings and good operation. With differing designs of different manufacturers then poss not. I suspect that, in practice, the same plant manufactures the same designs but differi.ng badges. I`d say at least a C3 and poss a C2.

Martyn you say you don`t like C3s  . What about, for example, wrong colour coding of conductors?

Any one of us opening a lightswitch sees all sorts of wrong colour coding often.  The electric in the circuit does not care, it still works as safely (or unsafely) as it would in a correctly coloured cct. Anyone opening up the switch should be competant enough to know that, otherwise they should not open it.

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.

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!