Diversity Factor
- Thread starter hard-work
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Table 41.1.You tell me
As I said, that relates to the BS7671 requirements for disconnection times.
On the other hand, the curves and tabulations in Appendix 4 relate to the characteristics of OPDs. Fig 3A4 gives the characteristics for Type B MCBs. In terms of the graph, it is impossible to distinguish between 0.1 sec and ~11sec (or anything in between), and the tabulations of 5 x In relate to "0.1 to 5 seconds" disconnection times.
I presume that the implication is that Type B MCBs satisfy the ≤0.4sec requirement of Table 41.1, but I don't think one can really claim that such is stated explicitly - either in BS7671 or its Appendices.
Kind Regards, John
The bus bar has about 4 or 5 flats off each bar. Not seen the fuses for each phase. From main fuse holder to the flat's CU and onwards is all fine being suitable for 100A.
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Are you saying that the bar which supplies the flat we're talking about also has 3 or 4 other (63A, 62A or 60A) fuses connected to it, supplying other flats (in other words, a total of 12-15 such fuses in the box)?
Could we perhaps have a photo of this fuse box?
Yep. I am not in the place for around a week.
Fair enough, but it does sound as if you are probably well out of your depth.
I also have to wonder if 'your' flat is appreciably different from all of the other dozen or so. Whilst the others may all have gas heating, it would not surprise me if at least some of them had electric showers - which would probably make them similar in terms of 'maximum electricity demand' to yours with UFH.
Nope.
From someone who was involved in installing 3 phase generators, I am far from out of my depth. The fuse cabinet is not the issue.
Well, one hopes that means that you wouldn't be out of your depth if we were discussing the installation of 3-phase generators - although I don't really see that installation of generators has much to do with what you have been discussing here.
I don't think that any of us have said that it is, but your entire problem seems to relate to the fact that the cabinet bears a "63A only" sticker, doesn't it?
That is not a problem as it cannot be solved. It stays at 63A. The problem is inside the flat. The problem boils down to a calculation, which as a few have mentioned, may be better substituted by a common sense.
That seems a rather odd thing to say - since, were it not for that "63A" sticker, you would presumably have had no reason to start this discussion?
I would be one of those 'few' - and, as I have said, and for what it's worth, my view of the common sense is that you really should not have any concerns. However, as you do seem to have concerns, it seems that you probably need someone with sufficient knowledge and understanding to advise, hopefully reassure, you.
Why not just stick a clamp meter on the flats incoming supply and see what actualy happens if you simulate a realistic maximum demand situation?
Then you can see if you do actualy have a problem or if you can stop worrying about it.
Then you can see if you do actualy have a problem or if you can stop worrying about it.
It's all a bit confusing, but the impression I get is that most of what we have told about is hypothetical, such that there is not currently very much in situ to actually measure - the OP seems to still be considering thermal store wet UFH & DHW as a possible option and is still debating the types of cooking/laundry appliances. However, maybe I have misunderstood.
However, the OP appears to have admitted that the 'problem' (which is causing his concerns) exists only because of a "63A" sticker on the fuse cabinet.
Kind Regards, John
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