In message ,
The Natural Philosopher wrote:

Jon Weaver wrote:



Can anyone comment on this? Bearing in mind that the lengh of the
inslated cable is less than 10", is it really a concern? I guess that
a consideration is that the insluation won't be 'surrounding' the
cable, instead it will simply be on top... A crude cross section of
the installation is as follows:

----------------
Ceramic Tiles
----------------
Adhesive
----------------

Screed

----------------

Insulation

----------------
++++++++++++++++ DPC
~~~~~~~~~~~~~~~~ Metal Capping
================ 2.5mm Cables (Layed side by side)
----------------


Concrete


----------------


Why not lay them in the screed then?


According to table 3A in the On Site Guide, PVC cable is "unsuitable for
embedding directly in concrete".

However, I will re-state my previous advice. In the situation described
above, 2.5mm cable *is* suitable for carrying the current of a 32A ring
main. It may be "covered" with insulation, but it is "in contact with a
[thermally] conductive surface on one side" (method 15) and is therefore
capable of carrying up to 21A (table 6F, OSG). There *may* be a grouping
issue, but I don't think so over this short distance with FTE.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Don't fight technology, live with it: http://www.livtech.co.uk/
.... Visa, Visa, Viso - I shopped, I shopped, I ran out of cash.