wrote:
I have only just found the self build wiki as a result of a link on
laminate flooring thread and have been having a browse:
http://www.sbfaq.borpin.co.uk/dokuwiki/doku.php


In the electrics section, regarding cable capacities it says:
The current carrying capacity of typical cables a
6242Y T&E : 1.0mm2 14A
6181Y Single: 1.0mm2 11A

Why is the capacity of the single significantly less than the T&E?

I would have thought it would be the other way round as there is
potentially twice the current flowing in the T&E cable and hence a
higher heating effect.

Consider the overall circumference of the cable.
The plastic is a very poor (thermal) insulator.

This means that essentially, the copper size is irrelevant to its
thermal properties (of course, it's important with regards to how much
heat is generated in the first placE), the only thing of importance
being the overall circumference of the cable, and the environment it's
in.

If a 1mm^2 copper conductor is generating 1w/m^2 of heat along its
length, it's going to be cooler if the heat emitting surface is 30mm(/2)
(guess) of insulation, rather than 11mm.