Underground Cable Bedding & Backfill
A buried power cable is only as good as the material around it. Thermal bedding sand is graded to pack tightly and conduct heat away from the conductor.
Why the backfill matters
A cable carrying current makes heat. If the heat cannot escape, the conductor runs hot and the cable has to be derated — run below its design current — or it fails early. The material around the cable is the path the heat takes to the ground. Air resists heat, so the fewer air voids in the backfill, the lower its thermal resistivity and the more current the cable can safely carry.
What matters in the sand
Density. A well-graded sand — one with its full range of particle sizes, fines included — packs into a tight mass with few voids when it is compacted around the cable. A washed, single-sized sand does the opposite: it leaves voids, and voids are air. This is why thermal bedding sand is not washed: the fines that would be stripped out are the ones that let it compact.
The MRP product
Thermal Bedding Sand is screened and graded to retain its fines and compact densely, and supplied for placement around cables in trench, at substations and across renewable energy grid connections. Where a project also needs engineered fill for the platforms and access above, Select Fill is supplied alongside it.
Supply
Bulk supply to electrical contractors, civil contractors and utilities across South East Queensland, scheduled against the trenching program. Tell us the project, the specification or thermal resistivity requirement, the tonnage and the site.