Whats this cable?

[stillp]

Yes, sorry, at 20°C

 

[JohnW2]

I believe that BS6004, along with other BSs, has credibility on other countries, so maybe the manufacturer sees that marking as a marketing advantage, but doesn't want any breaches to be too easily detected.

Fair enough - but, based on what you have said, by labelling with "BS6004", but without the CSA labelling (as apparently required by BS6004), they seem to have produced a built-in proof of non-conformity with that Standard

Kind Regards, John

 

[JohnW2]

The maximum resistance for 2.5mm² plain copper conductors is 7,41Ω/km.

Interesting - so, when it is actually is 2.5mm² (and if I've got my sums right!) that seems to imply a maximum resistivity of 1.8525 Ω.m, which is rather different from the 1.678 Ω.m figure (at 20°C) that was previously being discussed.

Looked at the other way around, if the resistivity actually was 1.678 Ω.m, then the above requirement would imply a minimum CSA of 2.265mm² for (nominally) 2.5mm² conductors.

Kind Regards, John

 

[EFLImpudence]

The maximum resistance for 2.5mm² plain copper conductors is 7,41Ω/kM.

Also interesting as that is the value given in tables even though it does not correlate to the value of 10mm² - 1.83x4 = 7.32mΩ/m

 

[JohnW2]

The maximum resistance for 2.5mm² plain copper conductors is 7,41Ω/kM.

Also interesting as that is the value given in tables even though it does not correlate to the value of 10mm² - 1.83x4 = 7.32mΩ/m

I'm surprised to see you quoting figures from the OSG

In any event, we have discussed before the fact that the figures are not precisely linear. You could equally have compared (from that Table):
50mm² & 2.5mm² - 20 x 0.387 = 7.74 (not 7.41)
25mm² and 2.5mm² - 10 x 0.727 = 7.27 (not 7.41)
16mm² and 2.5mm² - (16/2.5) x 1.15 = 7.36 (not 7.41)
1mm² and 2.5mm² - (1/2.5) x 18.10 = 7.24 (not 7.41)
etc. etc.

Kind Regards, John

 

[EFLImpudence]

Not the OSG
http://onlinelibrary.wiley.com/doi/10.1002/9780470998373.app4/pdf and others.

If you start your comparing calculations from the 1mm² or 10mm² values the results are a lot closer - apart from the 2.5mm² which is why I commented about Stillp's post.

 

[JohnW2]

Not the OSG
http://onlinelibrary.wiley.com/doi/10.1002/9780470998373.app4/pdf and others.

Fair enough - but the figures in the OSG Table (which only goes up to 50mm²) are identical to those given in that "Guide to the Wiring Regulations".

If you start your comparing calculations from the 1mm² or 10mm² values the results are a lot closer - apart from the 2.5mm² which is why I commented about Stillp's post.

Yes, you get different answers according to what you use as your starting point, but the fact remains that virtually none of the comparisons are precisely linear. Even the 1mm² and 10mm² figures are not perfectly pro-rata. Some of that will be accounted for by rounding errors, but that alone cannot explain the apparent discrepancies. However, of course, none of those 'discrepancies' are remotely large enough to be of any practical importance!

Kind Regards, John

 

[EFLImpudence]

but the figures in the OSG Table (which only goes up to 50mm²) are identical to those given in that "Guide to the Wiring Regulations".

That must be where they copied them, then.

 

[JohnW2]

but the figures in the OSG Table (which only goes up to 50mm²) are identical to those given in that "Guide to the Wiring Regulations".

That must be where they copied them, then.

Not quite - they both seem to have copied them from BS6360!

Kind Regards, John

 

[EFLImpudence]

Good grief, I don't think OSG would go near anything like that.

 

[JohnW2]

Good grief, I don't think OSG would go near anything like that.

Well, whether they "went near it" or adopted an indirect approach, the OSG ended up with the BS 6360 figures

Kind Regards, John