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Are Hager MTN MCBs backwards compatible with Hager MT MCBs? EVSE consumer unit upgrades.

An apparently straightforward question 

www.edwardes.co.uk/.../hager-mtn132-32a-b-type-mcb-6ka

Parents
  • Only Hager could answer the question as to whether they say the MTN is compatible with the MT unit.

    OK, I take the point regarding "no less safe", but if someone made it "less safe" in the first place, that's no excuse for another installer to follow suit.

    Finally, no-one (including BS 7671) has said you can't fit other devices into a consumer unit, but that the original manufacturer won't be responsible for the assembly. This is clearly logical and reasonable, and was also the case before BS 7671 reminded us about it - a manufacturer can only test what they know, not every eventuality! This also might help:

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  • Only Hager could answer the question as to whether they say the MTN is compatible with the MT unit.

    OK, I take the point regarding "no less safe", but if someone made it "less safe" in the first place, that's no excuse for another installer to follow suit.

    Finally, no-one (including BS 7671) has said you can't fit other devices into a consumer unit, but that the original manufacturer won't be responsible for the assembly. This is clearly logical and reasonable, and was also the case before BS 7671 reminded us about it - a manufacturer can only test what they know, not every eventuality! This also might help:

Children
  •  Graham,

    The thing with that old chestnut is that in reality it is just pure protectionism. All such kit has to be made to BS60898 for example, and that should be good enough. Just look at who comprises the BEAMA membership roll for the answer. Also, many manufacturers use a common supplier of mcbs and just re-label them with their own branding. So does this mean that a different label on 2 identical mcbs makes them incompatible?

  • The thing with that old chestnut is that in reality it is just pure protectionism. All such kit has to be made to BS60898 for example, and that should be good enough.

    That depends upon how specific the BS is. It would be a queer business if one could only use MK plugs in MK sockets. However, the two types of Wylex MCB are certainly not interchangeable - the busbar won't fit.

  • The thing with that old chestnut is that in reality it is just pure protectionism. All such kit has to be made to BS60898 for example, and that should be good enough.

    Here we are talking about a type-tested assembly of products to a particular standard.

    A manufacturer carries out the (very expensive) type tests with a range of equipment (from their own product ranges).

    Are you suggesting that they either:

    (a) ought also to test other manufacturers' equipment?; or

    (b) that the product standards for protection, control, SPD, etc., devices, are deficient in not specifying appropriate limits for ALL physical parameters (including mechanical), AND the type-tested assembly standard somehow cover tests assuming worst-case conditions of the product standards?

    I think there are a number of issues with (b), that stifle innovation, but I'm sure the relevant BSI committees responsible for those standards would welcome input and ideas to improve standardization.

  • I believe that b) would indeed provide an ideal solution, otherwise the manufacturers are just duplicating effort. What is the point in Maker A testing the mcbs in his range which come from the same factory as those from Maker B who has already done the testing?

    How much science actually goes into designing a simple steel box to contain it? All they have to do is ensure that holes and brackets are drilled/affixed in the correct locations and that the correct gauge of steel sheet is employed for the application. I'll bet more study goes into the type of paint and finish than anything else,

    We are not designing a spacecraft here, but merely a steel box, some fixing holes and brackets, and a durable paint finish.

    As for stifling innovation, I'm pretty certain that the BSI committees are aready doing that all by themselves.

  • Not having access to BS EN 61437 I can only speculate on the requirements, but I imagine it might include: tests of the assembly being subjected to 4kV; that nothing overheats when full of MCBs with currents near their max rating while at a high ambient temperature; that when a breaker trips and extinguishes the arc, any expelled hot arc gases don't damage anything; and for annexe ZB, testing with a 15kA fault (with an upstream BS88 fuse) and making sure the whole box doesn't explode.

    So I think there's a bit more to it than bashing out a metal box and adding a DIN rail.