摘要 |
A cable surround material 1 for a cable 2 of an electricity transmission system comprises a mixture of an additive including a carbon family element and cement. The carbon family element may be carbon, for instance coke, or may be silicon. The cement may be Portland cement. The trench 3 may also include protective slabs 7 of concrete, another backfill material 4, and a surface covering 6 eg of tarmac. The cables may rest on a temporary support, or may be laid on material already in the trench. Ducting may be used. The cable surround material is thermally conducting and so allows thinner or fewer cables to be used. |