Cable sand words, in plain English

0/2 and 0/4 sand

Ways of describing sand by particle size: 0/2 means grains from dust up to 2 mm, 0/4 up to 4 mm. Suppliers use these on data sheets.

Artic

An articulated tipper lorry. Carries about 28 to 30 tonnes, the lowest haulage cost per tonne where the site can take one. Delivery

Backfill

The material that fills the trench back to ground level above the sand and warning tape, often the dug-out soil if the spec allows.

Bedding

The compacted layer of cable sand along the bottom of the trench that the cable or duct is laid on. Trench bedding guide

Blinding

The cable sand placed over and around the cable once it is laid, packed in by hand so nothing is damaged. Trench bedding guide

Bulk bag

A large lifting bag of sand, about 850 kg in ours, lifted off the lorry by its own crane. Also called a dumpy or tonne bag. Delivery

Cable sand

Clean, fine sand laid under and over buried power cables to keep stones off them, give them a firm bed and carry heat away. Also called selected sand, thermal sand or ducting sand. What cable sand is

Cable tiles

Tough covers laid over a buried cable to protect it and warn anyone digging. The spec says whether to use tiles or tape.

CBS (cement-bound sand)

Sand mixed with cement, usually 14 parts sand to 1 part cement. Holds together and keeps carrying heat away once dry, so it is often used at higher voltages. Also called stabilised sand. Cement-bound sand

Cohesion

How well compacted sand holds together. ENA TS 97-1 tests it on selected sand.

Compaction

Packing sand down so it is dense and does not settle, by vibrating plate on open layers and by hand around cables and joints.

DNO (distribution network operator)

The company that runs the local electricity network in an area, such as Northern Powergrid or UK Power Networks. Each sets its own rules for cables joining its network.

Crushed stone dust

Crushed limestone or granite, 3 mm down to dust. National Grid Electricity Distribution specifies it instead of sand to bed and blind its cables in the Midlands, South West and South Wales. We supply it.

Duct

A plastic pipe laid in the trench for a cable to be pulled through, now or later. Ducts are bedded and surrounded in sand like cables.

ENA

The Energy Networks Association, the trade body for the UK’s electricity and gas network operators. It publishes ENA TS 97-1.

ENA TS 97-1 (ENATS 97-1)

Energy Networks Association Technical Specification 97-1, "Special backfill material for cable installations": the industry standard for the sand and other backfill around power cables.

Fluidised thermal backfill

A flowable mix poured into the trench rather than laid and compacted. A specialist engineered backfill with its own test results. Thermal backfill

Gravel and sand mix

Selected sand mixed with an equal weight of small single-size gravel. One of the three traditional backfills in ENA TS 97-1.

Hold Point

A stage in ENA TS 97-1 that work cannot go past without the engineer’s written approval: handing over the test documents before work starts, and passing the trench tests after the cables are blinded.

ICP (independent connection provider)

An accredited contractor that builds new connections to the network, which the network operator or an IDNO then adopts. Utility contractors

IDNO (independent distribution network operator)

A company that owns and runs local networks, usually on new developments, connected to the main operator’s network.

kV (kilovolt)

A thousand volts. Cable jobs are described by voltage, such as 11 kV or 33 kV, and the higher the voltage the more often the spec asks for cement-bound sand.

Routine tests

Tests of the compacted sand in the trench as a job goes on, which ENA TS 97-1 sets alongside the sample tests.

Sample tests

Lab tests on samples from the quarry before a job starts, recorded on a test sheet for the source quarry.

Selected sand

ENA TS 97-1’s name for plain cable sand: natural sand from a tested source, fine, clean and free of stones, clay lumps and organic matter.

Special backfill

The name network operators’ rules and ENA TS 97-1 use for the sand and other materials placed around power cables.

Stabilised sand

Another name for cement-bound sand: sand bound with cement. Also called stabilised backfill or cement stabilised backfill. Cement-bound sand

Thermal backfill

Any material packed around a buried cable to carry its heat away: cable sand, cement-bound sand, gravel and sand mix, or an engineered product. Thermal backfill

Thermal resistivity

How hard it is for heat to pass through a material, measured in K·m/W. The lower it is, the better a backfill carries heat away from the cable. Thermal backfill

Tipper

A rigid tipper lorry. An 8-wheeler carries about 20 tonnes; smaller tippers suit tight sites. Delivery

UKAS

The United Kingdom Accreditation Service, which accredits testing laboratories. A UKAS test certificate means an accredited lab did the tests.

Warning tape

Printed plastic tape laid in the trench above the sand, so anyone digging later finds it before the cable.

A word missing? Try the questions page, or ask us.