Hi Folks,
I have been giving a bit of thought to direct buried cables and was looking around for the ‘Best’ method for installation in reference to current carrying capacity especially with the rise in copper prices. 96A vs. 152A on something as small as a 25mm 4c or 365A Vs 592A on a 300mm 4c.
The differences between ERA & BS7671 figures are significant and they seem to come down to actual installed conditions, for example ERA have an assumed thermal resistivity of 1.2k.W/m vs. that of BS7671 which uses 2.5k.W/m.
I got to thinking is there an installation method that could be more readily assured to be better in terms of thermal resistivity?
Damp compacted sand would seem to be the best for decreasing thermal resistivity, but how much? would a liner in the base of the trench be of any use to reduce drying or migration of the sand or might this just add to the overall thermal resistivity?
I read this earlier https://ictinternational.com/casestudies/underground-power-cable-installations-soil-thermal-resistivity/
And then what about the ‘New’ Conducrete? could encasing in such material have significant benefits or might this risk damage with settlement?
Thoughts?
