Fair enough - but in view of the discussion I've been having with EFLI, would it actually make any difference?I just thought it might be worth making sure that it really is straight concentric, and not single core SWA.
Kind Regards, John
Fair enough - but in view of the discussion I've been having with EFLI, would it actually make any difference?I just thought it might be worth making sure that it really is straight concentric, and not single core SWA.
You should have read the end of that back-and-forth, If you had, you will have seen the agreed conclusion that, as far as the regs are concerned, it would seem that any cable with an earthed metal covering is seemingly deemed OK for burying, provided only that the metal covering is "adequate as a CPC", seemingly regardless of the material or mechanical properties of that covering.I stopped reading the back-and-forth between you two when it became apparent that it was pointless.
Having just measured, a hair from my head is bout 40 microns
I don't know. Is there a definition of a minimum level of mechanical protection?
That's about conduit, so I doubt it has any direct relevance to the outer coverings of cables.Read 521.6 and wonder if BS EN 61386 or BS EN 50085 have anything to say about that.
Possibly, but I suspect not. Let's face it, SWA has a very long history of using that description but, as EFLI and I were discussing, give me a spade and I'll get through any modest-CSA SWA for you So, even if "armoured" has some sort of definition/requirements, that probably has little practical meaning.And what about cable standards? For a cable to legitimately describe itself as "armoured", does it have to meet any minimum level(s)?
Again who knows, but I would doubt that such a description means more than it says, hence with no requirement for mechanical properties.Ditto "metal sheathed"?
What about the 'ali-tube' cable we're always hearing about here (but which I have never even seen)?Incidentally, does anybody know of any "metal sheathed" cables (in a UK context) other than MICC/MIMS?
Those thicknesses are all about (but not exactly ) twice what I get.Considering , say, an ~12mm diameter earthed covering, it would only have to have a thickness of about 0.08mm (80 microns) to have a CSA of 1.5mm², or a thickness of about 0.135mm for a CSA of 2.5mm² or a thickness of about 0.27mm for a CSA of 4mm².
12mm OD ... but you have made me realise an error in what I did....Those thicknesses are all about (but not exactly ) twice what I get. What value did you use for the circumference of your 12mm diameter cable?
And ducting.That's about conduit, so I doubt it has any direct relevance to the outer coverings of cables.
Well yes - as you go up the scale, spade, JCB, shaped charge..., it of course becomes harder to defend against an "attack".Possibly, but I suspect not. Let's face it, SWA has a very long history of using that description but, as EFLI and I were discussing, give me a spade and I'll get through any modest-CSA SWA for you
Au contraire.So, even if "armoured" has some sort of definition/requirements, that probably has little practical meaning.
That might also be incorrect.Again who knows, but I would doubt that such a description means more than it says, hence with no requirement for mechanical properties.
That is not a metal sheathed cable.What about the 'ali-tube' cable we're always hearing about here (but which I have never even seen)?
That can be your assignment.... and how does SY fit into this spectrum, I wonder?
I considered the difference between OD & ID as insignificant, i.e. I took the circumference of the metal layer to be 12mm in all cases, even though on the inner surface it would have been slightly less.12mm OD ... but you have made me realise an error in what I did....
... I took the ID being OD-thickness, whereas it should have been OD-(2*thickness). So, yes, doing it properly (with 12mm OD) I get (roughly) ...
Much closer to what I got1.5mm² ... 0.0399 mm thick
2.5mm² ... 0.0667 mm thick
4.0mm² ... 0.1070 mm thick
Again, it aint necessarily so.I think the point that might be getting missed here is that (as with cables buried in walls) the reg is offering an earthed metal covering as an alternative to mechanical protection, so one wouldn't necessarily expect the earthed metal to be required to provide any 'mechanical protection'.
Are there any official definition(s) or standard(s) for SY cable? Is it classed in anything de jure or de facto as "metal sheathed"?
Eland Cables said:"SY cables, also known as armoured flexible control cable, shielded flex, or simply armoured flex, are strong and durable cables suitable for internal dry, damp or wet environments (including oil-water mixtures), and can be used outdoors when protected against direct sunlight. They are also referred to by their constructional reference: YSLYSY cables for the PVC sheathed variation.
SY control cables are not suitable for fixed wiring applications requiring compliance with the requirements set out in BS7671".
I just thought it might be worth making sure that it really is straight concentric, and not single core SWA.
I'm sure that it was perfectly OK for the purpose. However, using the method I used (see below), if I had assumed that the inner and outer diameters were the same, I would have got a CSA of zero !I considered the difference between OD & ID as insignificant, i.e. I took the circumference of the metal layer to be 12mm in all cases, even though on the inner surface it would have been slightly less. .... Much closer to what I got ..... So close that the differences are explained by your more precise consideration of the different diameters involved, and so close that I was right that using a constant diameter of 12mm was perfectly OK.
Nope. In fact, I was not using circumference at all.But come on, John - there's no way that your original figures can be explained by using OD-thickness instead of OD-(2*thickness) .... 12mm dia = 37.7mm circumference. .... Your original figures imply mean circumferences of: .... You were using πr instead of πd, weren't you...
data DIYnot1 (keep = thickness csa) ;
OD = 12 ;
pi = constant("pi") ;
do thickness = 0.01 to 0.3 by 0.00001 ;
CSA = ((pi * OD**2) / 4) - ((pi * (OD-(thickness*2))**2) / 4) ;
if CSA >= 1.5 and CSA_prev < 1.5 then output ;
if CSA >= 2.5 and CSA_prev < 2.5 then output ;
if CSA >= 4 and CSA_prev < 4 then output ;
CSA_prev = CSA ;
end ;
run ;
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