Thermal testing of soils and cable backfill
for the renewable energy sector

Soil Thermal Resistivity Testing (STR)

Soil Environment Services (SES) have been testing soil and backfill to the Energy Networks Association specifications for 15 years. We test soils, rocks, and cable bedding materials such as Cement Bound Sand and in recent years have worked with some of the biggest cable laying companies on the longest cable routes in the UK.  Testing is undertaken in our highly specialised laboratory which includes a Calibrated Hotbox to test alternative backfill to BS8990 standard. .

Laboratory Services

Cable backfill testing
(ENA TS 97-1 / NGTS 3.05.07)


  • Cement Bound Sand (CBS)
  • Selected Sand
  • Gravel Sand
  • Alternative Backfill (BS8990 – Calibrated Hotbox).


  • Thermal Resistivity
  • Dry Density
  • Voids Ratio
  • Cohesion
  • Particle Size Distribution

Thermal Resistivity (TR) of soils and solid rock cores
(ASTM D5334-14 / IEEE Std 442)


  • Soils (Bulk or core samples)
  • Rock Cores


  • TR at received moisture
  • TR fully dry (fully dried at 105C)
  • TR at specified density and/or moisture
  • TR dry out curve
If you require cable backfill, soils testing in the laboratory or field, please call us to discuss your exact requirements as sample treatment prior to testing is crucial.

We test in accordance with the following specifications:

ENA TS 97-1 2016
ASTM D5334 – 14
IEEE Std 442 -2017
BS EN ISO 8990: 1996 – Hotbox
National Grid TS 3.05.07
BS 1377

In-Situ Thermal Resistivity Testing

Soil Environment Services can test the natural soils and rocks along a cable route before ground has been broken, CBS and backfill in trenches and ground within a substation. All on site testing is  to National Grid and Energy Networks Association technical specifications. Training client’s staff is undertaken for routine testing of trench backfill density.

Recent Project Examples

CBS testing during cable pulling. Crossaig Substation OMEXOM, Mull of Kintyre.
CBS Density testing - Rothienorman Subsation

In-Situ CBS Dry Cured Relative Density Testing – Rothienorman Substation. More info.

ABB – Caithness to Moray 120MW, 50km on land cable route. More info.

Quality and Standards

ENA TS 97-1, Version 2 2016
ASTM D5334 – 14
IEEE Std 442 -2017
BS EN 8990:1996
National Grid TS 3.05.07
BS 1377

Laboratory Contact Details

Contact Dr Robin Davies  to discuss your requirements.

Unit 8
Stocksfield Hall
NE43 7TN

01661 844827