Is the use of 3mm sleeving on the CPC for ring main (2.5mm T&E) and lighting (mix of 1.5mm and 1.0 mm) switches, sockets etc likely to fail a PIR or other inspection - if only on the basis of "good workmanship and practices" please?
I've been using it as I had a reel and TLC had nothing smaller in stock. But a comment overheard at the Screwfix trade counter has left me a bit bothered, and I'd rather re-do the work now than later.
No. What was your concern? That you could use something thinner?
Thanks for that
Yes - I thought I heard someone who appeared to be in the trade (from the bulk of their order) say that 3mm was too big. And I have in the past always used smaller sleeving for CPCs when doing odd bits and bobs.
Its bigger and hence not as easy to work with in the confines of a socket box etc, but I can't see any reason for it being unacceptable.
And it's what almost everybody seems to use. I doubt that many wholesalers even bother to stock 2 mm (although it's easy to get from RS etc). 2mm definitely makes a better-looking job though.
What really needs stamping out is the old practice of twisting several earths tightly together and sleeving the whole lot as one.
Why is that bad practise?
clangers snipped-for-privacy@yahoo.co.uk coughed up some electrons that declared:
It can make it difficult to break the circuit at that point for testing (eg a PIR).
Cheers
Tim
Testability & maintainability: it make it difficult to disconnect individual conductors where necessary for testing (either initial or PIR) or during fault tracing.
Alterations: it can be a pain when adding or removing cables during alteration work.
Conductor identification: all conductors in an installation should be identifiable.
Also tight twisting work-hardens the conductors and renders them liable to break when being disturbed, giving more grief during any of the above operations.
See also the post by John Peckham in this thread:
Just had a look at my bundle of it - turns out that is 3mm as well...
Indeed!
After 30 years I've got round to doing a PIR on my own wiring. I've cursed several times at the above practice whilst investigating strange resistance readings on the upstairs ring.
I seem to have 3mm and 5mm.
Although I do keep a stash of about 10m of 6mm for the 16mm T&E etc stored under the drivers seat along with the 3mm red and black off cuts that should last for years.
Adam
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