I do not know.
I would not be surprised if it did, and I could see the sense in such.
inaccessible Junction Boxes
- Thread starter adamr7747
- Start date
I would not be surprised if it did, and I could see the sense in such.
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What about one J803/4 connector in a chockbox?
I know it's hypothetical but the point is that having the MF verification markings on the container is not really related to the connections .
I know it's hypothetical but the point is that having the MF verification markings on the container is not really related to the connections .
As BAS has said, it would not surprise me at all if such an overall assembly ceased to be 'MF'.
I would say the same as above. I don't think anyone has claimed that the connectors within a J803/4 are, in themselves, 'officially MF'.
Isn't this another case of 'type testing', as with CUs? In other words, for the totality of an assembly to count as an 'MF junction box', does not the enclosure have to contain (and only contain) components recommended/approved by the manufacturer - the hope/intention being that such assemblies of enclosure/contents will have been tested by the manufacturer.
In relation to CUs, a good few of us feel that if the devices concerned (MCBs, RCDs, RCBOs etc.) are fully mechanically (dimensionally) compatible with a CU, then the risk of their being a problem with using devices not 'approved' by the manufacturer of the CU are so small as to not really be relevant - but some (like stillp) seem to feel strongly against that view.
I would personally take a similar view of non-screw connectors (i.e. that it should not be necessary for 'MF connectors' to be within a particular enclosure to be 'MF') - after all, it is the connectors themselves are really what makes the joining 'MF'. However, the problem with that at the moment seems to be that, as far as I am aware, there are no connectors which, themselves, are 'MF' - only ('type tested') assemblies of connectors+enclosure currently appear to be 'MF'.
Most of this comes down to a question of what BS 5733 says - so let's hope that someone can tell us.
Kind Regards, John
Surely that is the only part that must be MF; i.e. different than a non-MF (screw connector) - as you apparently later contradict this quote and agree.
What about an additional J803/4 connector in a J803/4 box - how can that NOT be equally MF?
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Yes, I agree that the characteristics/performance of connector itself is the crucial bit (just as I think that the characteristics/performances of the devices within a CU are the crucial bit), but there are undoubtedly other requirements for an 'officially MF' junction box (presumably specified in BS 5733) - e.g. regarding cable restraint. Particularly interesting is what Wago say about 'down-rating' the Wago connectors and imposing a limit on the 'aggregate' current within a Wagobox if one wants conformity with BS 5733.
This underlines the fact that we need to know what BS 5733 requires of an MF JB, since it seems that, rightly or wrongly, it may well relate to quite a lot more than just the connectors (when used 'normally').
See above. If BS 5733 imposes requirements such as maximum aggregate current, then that might mean that what you suggest would/could be non-conformant - and it is certainly unlikely to be an arrangement that had been 'type tested' by the manufacturer.
Common sense-wise, I'm very inclined to agree with you. In other words, if a connector itself was deemed to be suitable for use as 'MF', then I would expect to be able to put as many as I wanted into any enclosure which provided adequate cable restraint, and not to have to 'down-rate' the connectors. However, I need not tell you that common sense does not necessarily always prevail, particularly given that what I regard as my 'common sense' views about CUs seems to get over-ruled!
Kind Regards, John
You're talking about 'certification' again, and I'd like to hear more about this from someone who actually understands. As I said before, it's surely possible for a product to conform to relevant Standards without any 'formalities', so I wonder what 'certification' you have in mind.
Kind Regards, John
That seems similar to the J803 and J804.
The number of connector blocks being the only difference.
The J803 has three connector blocks and is rated at 32A,
The J804 has four connector blocks and is rated at 20A.
Indeed so - so, again, we need to know what BS 5733 says...
Quite so - what what were you thinking would be the consequence of adding, say, a fifth connector block to a J804? [if, for example, it resulted in a further 12A reduction, there would not be much 'rating' left
]Kind Regards, John
Damnit - replied rather than edited, again!
It could be used on a 6A (lighting) circuit where it is more likely five might be needed.what what were you thinking would be the consequence of adding, say, a fifth connector block to a J804? [if, for example, it resulted in a further 12A reduction, there would not be much 'rating' left
I would think that the 32A and 20A ratings are more nominal, coinciding with MCB ratings, than an absolute tested maximum.
True.
I do not doubt that they are - but the fact that they are different is interesting - again, quite possibly down to BS 5733.
As I've implied, I really don't understand this 'down-rating' and imposition of a maximum 'aggregate' current business at all - whether it is due to BS 5733 or whatever. One might think that it could have something to do with thermal considerations - but if the implication is that the contact resistance of the connectors is such that significant heat in generated in them, then they would surely not be fit for purpose, would they?
Kind Regards, John
Good point. I hadn't given it much thought.
I just assumed that it was that four connectors had more conductors - all of which may be at 70° - but, of course that has nothing to do with the current, has it.
Having said that, three phase cables have a lower rating than single phase for the same csa; is that the same?
Yes, I suppose that it may be related to heat generated in the cables, rather than at the 'joint' (which one would hope would generate minimal heat).
That obviously does have 'something to do with current', since the 70° relates (we assume) to the conductor carrying its maximum rated current.
However, if that's the thinking, it's more to do with 'cable grouping within an enclosure' than anything to do with the connectors (MF or otherwise). Mind you, if that were the thinking, then I suppose it would explain the enclosure-specific requirement, since the temperature attained by a pile of current-carrying conductors within an enclosure would obviously depend on the size, shape and materials etc. of that enclosure. ... so I suppose that might explain why Wagos or J803/4 connectors cannot be put into 'any old enclosure' and then regarded as MF??
However, as above, that's all about having multiple current-carrying cables/conductors within an enclosure. It's not specifically related to the fact that there are 'joints' within the enclosure (i.e. not specifically related to a 'JB') and, even if it is a JB, it's not clear (to me) why it's a consideration for MF ones but not for non-MF ones.
Yes, similar story, I suppose ... if one has three conductors in a cable each carrying X amps, then the conductor temperature achieved will presumably be higher than if there were only two conductors each carrying that current - so, t'other way around, for the same max conductor temp, the max permissible current (per conductor) would be lower when there we three conductors, rather than two.
Kind Regards, John
What I meant was that even 6A conductors could be at 70° - so, limiting the rating of the box does not mean the temperature inside will be lower.
The 804 can still have more conductors at 70° than the 803.
Yes, but if you had a conductor which 'alone' would achieve a temp of 70° with 6A flowing (probably not possible with available cables and regulations), then if there were two or more of those within a confined space, you would have to reduce the current to less than 6A in order to limit the temp to 70° (because of the raised ambient temp).
Indeed, but the same issue. Yes, it could be that they are trying to limit all conductor temps to 70° - but the more conductors one has in a confined space, the lower the current that can be 'allowed' if the temperature of (all of) the conductors is to be limited to 70°.
As I said, just like 'grouping' of cables.
Kind Regards, John
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