Stranded 2.5mm T&E cable

[pc1966]

Recently a couple of threads have discussed T&E cable and it became apparent to me that the 2.5mm, which I have only ever seen as solid core, is available with the live cores in 7-strand (rather like the old 7/.029" imperial size, though with solid CPC and not the 3-strand seen before). In fact CEF list it as available (but not stocked locally, as usual, and no maker information):

H6242Y 2.5mm² PVC T+E Twin and Earth Stranded Core Cable Grey (100m Drum)

Twin & earth with stranded cores

www.cef.co.uk

Does anyone know of specific use-cases where this is specified?

Has it simply been familiarity with previous installations using the stranded imperial size?

 

[Risteard]

I've been impressed by Edmundsons, in terms of pricing and stockholding, at least with a local company owned by Edmundson electrical.

Mercers?

 

[nicebutdim]

Mercers?

Yes. I figured 'owned by Edmundsons' was likely to mean more than Mercers, to anyone outside NI.

 

[Simon47]

While I've only been buying small amounts - mostly trunking, fixings etc at my last job when I occasionally got network install jobs to do, and now just occasionally for myself and our rental properties, I've found the local CEF branch really good. Staff really helpful, and often it ends up with "come back 'ere" and I get to see what they have on the shelves - makes things a lot easier when I'm not entirely certain what's going to work best for a job.
I recall they were pretty good when I'd be adding networking to some random dado trunking - the guys there would often be able to identify the make/version and get the backboxes in for me.
At my last job, it certainly helped that they were the closest (few minutes walk from the office).

Stranded vs. Solid Wire Cable: How to Choose

Both shielded and unshielded twisted-pair copper cable comes in either stranded or solid wire versions. There are plenty of considerations when it comes to choosing one or the other, including standards, environment, application, and cost. Let’s take a look at the differences and considerations...

www.flukenetworks.com

have a read. Interesting. every day is a learning day.

Bear in miind that is for network, not power, cables.

Until they say:
And because the cross section of a stranded conductor is not all copper (there’s some air in there), they also have a higher DC resistance than solid cables.
WTF? Not the same CSA then!

For data cables - yes there can be a difference in CSA. For data, the physical characteristics can be more important (or at least as important) as the electrical ones. To do with ratio between conductor diameter and spacing which sets the characteristic impedance, or something like that - changes in impedance cause reflections. I know from testing that you can see all the connections down a network link when doing TDR/TDX* measurements.

• TDR = Time Domain Reflectometry - send a pulse down a cable/pair and see what comes back on the same one.
• TDX = Time Domain Crosstalk - send a pulse down one pair and see what comes back on another pair. Cross-talk is one of the most critical parameters with twisted pair network cabling.