Cost surely isn't an issue. The small marginal difference between price of 6mm² and 10mm² cable is surely trivial in relation to the time, effiort, hassle (and potential cost) of having to dig around in the walls within 12 months, isn't it??
Given that it says "Number of circuits or multicore cables", I've no doubts that it's correct to count the number of multicore cables. After all, a circuit not using multicore would consist of 3, possibly 2, singles.
Yes, I'm pretty sure that's the right interpretation. On reflection, the reference to 'circuits' is probably there to cover singles - i.e. a pair of singles consitutes 'a circuit', and is hence equivalent to one 2-core cable. If that's the intent, they probably could have expressed/explained it a bit more clearly (after all, as we all know, a 'circuit' is a collection of things which shares a common OPD
)!
That would certainly be my view.
I'm not so sure about the 'permanently live' bit - I can see that raising all sorts of issues/deabtes!! Wouldn't it be far better without it (i.e. just 'number of L/N pairs')? Mind you, one would presumably also have to make some provision for 3-phase situations, for which 'L/N pairs' would fall flat on its face!
Did you seeing the following when I posted it and, if so, was it of any assistance:
If one takes the 'typical' external dimensions of T&E from the forum's wiki (which I mentioned before) and assumes that the shape is such that the cross-section can be represented as a rectangle with a semi-circle on each end, then what one can calculate is as follows:
However, guidelines in relation to CSA's is obvioulsy only part of the story when deciding what cables will even fit in what conduit (particularly if oval)!
I agree - but I suppose it would be impossible for the regs to attempt to cover all possible situations. Anyone is, of course, (unless constrained by employers, scheme operators etc.!) free to deviate from BS7671 if they can produce their own satisfactory engineering justification.
It seems that 'experiences vary'. FWIW, my experience is that even a single T&E in a plastic conduit plenty big enough for it can be difficult, particularly if the run is not dead straight. T&E seems to me to be really too stiff for this purpose - the slightest kink/bend in the cable can cause it to 'jam' in the conduit. Again, just IME, more than one T*E in any plastic coduit is definitely bad news in this respect. However, others (seemingly like yourself) seem to have much happier experiences.
luusac";p="2850084 said:
How did you work that out?
For 25mm oval? Probably not much more than 200mm²
90-100mm².
Won't even fit, let alone fit at 45%.
riveralt";p="2853860 said:
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