The guide

Cable sand: what it is and why cables are laid in it

Cable sand is a clean, fine sand laid under and over buried power cables and ducts. It keeps stones off the cable, gives it a firm, even bed, and carries heat away so the cable can run at its full load. On network operator jobs it usually has to meet ENA TS 97-1, the industry standard, which calls it selected sand.

Last checked 1 October 2026. Sources at the bottom of the page.

What cable sand does

Keeps stones off the cable

Sharp stones and flints in dug-out soil can press into a cable sheath when the trench is filled, or years later as the ground settles. A clean, fine sand around the cable takes that risk away.

Gives it a firm, even bed

Packed sand spreads the weight of the fill and anything driven over it, and does not settle or wash out from under the cable the way loose soil can.

Carries the heat away

A power cable gets warm when it carries current, and the ground around it has to take that heat away. Dry soil and loose sand are poor at it, so the cable runs hotter and has to be rated lower. The right sand, well compacted, keeps conducting heat even when it dries out, so the cable can carry its full load all year.

Where it goes in the trench

Cable sand goes in twice. First a bedding layer is spread and compacted along the bottom of the trench, so the cable or duct never sits on stones or rubble. Then, once the cables are laid, more sand goes over and around them asblinding, packed in by hand so nothing is damaged. Warning tape or cable tiles go on top, then the rest of the trench is backfilled.

1BackfillDug-out soil or imported fill, as the job specifies.
2Warning tape or tilesMarks the cable for whoever digs here next.
3BlindingCable sand packed over and around the cable, by hand.
4Cable or ductLaid on the bedding, never on stones or rubble.
5BeddingA compacted layer of cable sand across the full trench width.

How deep each layer is changes with the voltage and the network operator, so take the depths from your drawings or the operator’s rules.

Other names for it

It is the same material whatever it is called on the drawings or on site.

Cable sand: What most people call it.
Selected sand: The name in ENA TS 97-1, the industry standard. A natural sand from a tested source.
Special backfill: How network operators’ installation rules refer to it, along with the other backfills in ENA TS 97-1.
Cable bedding sand: From the layer it makes at the bottom of the trench.
Thermal sand: From its job of carrying heat away from the cable.
Ducting sand, duct sand, trench sand: Common on site, especially where ducts are laid.

The types used around cables

ENA TS 97-1 describes three traditional backfills. It also allows other materials, such as branded engineered sands, if they pass its tests. ENA TS 97-1 explained

Selected sand

Natural sand from a source that has been tested to ENA TS 97-1. Fine, clean and free of stones, clay lumps and anything organic. This is plain cable sand.

Gravel and sand mix

Selected sand mixed with an equal weight of small single-size gravel. Packs very densely and carries heat away better than sand on its own.

Cement-bound sand (CBS)

Sand mixed with cement, usually 14 parts sand to 1 part cement, also called stabilised sand. It holds its shape and its heat-carrying properties when it dries out, so it is often asked for around higher voltage cables.

Which one your job needs

Start with your drawings or the specification. On work that will be adopted by a network operator, their installation rules decide it, and they point to ENA TS 97-1 for the sand around the cable.

As an example, Northern Powergrid’s rules (NSP/002, 2021) say that low voltage and 11 kV cables are bedded on smooth material such as sand where the trench bottom is not smooth and stone free, and blinded with stone-free soil, selected sand or limestone dust. At 33 kV and above they ask for a 75 mm bed of selected sand or cement-bound sand, and the same over the top cable or duct. Other operators set their own rules, so check the ones for your area.

For a small job with no spec, such as a feed to a garden office or a car charger, a clean, fine, stone-free cable sand does the job. If you are not sure, pick “Not sure, advise me” on the form below and we will tell you what fits.

Buying cable sand

We deliver anywhere in the UK, including Northern Ireland and the Scottish islands: loose tipper loads, artic loads for long cable runs, or bulk bags where a tipper cannot tip. Sand is heavy, so the distance from the quarry makes the biggest difference to the price, which is why every job is quoted.

You can have a sample before you order, and you canask for our test certificate to check the sand against your spec.

Questions

What is the difference between bedding and blinding?

Bedding is the compacted layer of cable sand along the bottom of the trench that the cable or duct is laid on. Blinding is the cable sand put over and around the cable once it is laid, packed in by hand, before the warning tape and the rest of the fill go in.

Does cable sand need compacting?

Yes. Loose sand settles and carries heat away poorly, so ENA TS 97-1 expects it to be compacted, by vibrating plate on the open layers and by hand around the cables and joints. Very dry sand is hard to compact, so it may need dampening first. Your engineer or the network operator’s rules will set how it is tested.

Can I use building sand for cables?

On a small job with no spec, a clean, fine sand with no stones in it does the protective job. On any job for a network operator, the sand has to meet ENA TS 97-1 and come with test results, so building sand or sharp sand from a builders’ merchant will not be accepted.

Does a garden cable need cable sand?

A cable run to a garden office, workshop or car charger still needs protecting from stones, so it is normally bedded and covered in sand. How deep it goes and how it is protected is set by the wiring regulations, so follow what your electrician specifies. For a job that size, a bulk bag or two is usually plenty.

What else goes in a cable trench apart from sand?

From the bottom up: the sand bedding, the cables or ducts, the sand blinding, then warning tape or cable tiles so the next person digging knows the cable is there, then the backfill to ground level. The depths and materials change with the voltage and the network operator.

Sources

Energy Networks Association, ENA TS 97-1, Special backfill material for cable installations. The industry standard for the sand and other backfill around power cables.
Northern Powergrid, NSP/002 Policy for the Installation of Distribution Power Cables, version 5.0, October 2021. An example of a network operator’s own rules on bedding and blinding.

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