British and offshore standards: BS 5308, BS 5467, BS 6724, BS 7846 and NEK TS 606

Specifications from British or international engineering firms, and from the oil and gas industry, often call up British or Norwegian cable standards. They fix the construction of the cable, like the European standards, but they follow a logic of their own. When you meet them in a Dutch or Belgian project, watch three things: the earth, the fire performance and the CPR class.

BS 5308 is the British standard for instrumentation cable: measurement, control and signal circuits, not power. Part 1 has PE insulation and Part 2 PVC insulation, both for 300/500 V. Type 1 is unarmoured, Type 2 armoured with steel wire. Screening is a separate choice: a collective screen only, or a screen per pair with a collective screen around it. The standard itself was withdrawn back in 2005 in favour of EN 50288-7. Its successor PAS 5308 was withdrawn on 3 April 2024 as well. In the market BS 5308 has nevertheless remained the usual designation, and the cable is still made to that construction.

BS 5467 and BS 6724 are armoured power cables with XLPE insulation for 600/1000 V and 1900/3300 V. BS 5467 has a PVC sheath. BS 6724 has a halogen-free sheath with low smoke and corrosive gas in a fire; BS 5467 itself refers to BS 6724 where smoke matters. Multi-core cable has galvanised steel wire armour, single-core cable aluminium wire armour. Since the 2016 edition BS 5467 covers copper conductors only.

Earthing is where the biggest difference with Dutch practice lies. In the standard sequence of BS 5467 only the five-core cable has a green/yellow core. Two cores are brown and blue, three cores brown, black and grey, and four cores blue, brown, black and grey. The British wiring regulations, BS 7671, allow the armour to serve as the protective conductor, provided its cross-section is adequate. A four-core BS cable is therefore not a 4G: the earth runs through the armour and the gland. In the Netherlands or Belgium, agree that with the designer or the inspector beforehand.

BS 7846 is the fire-resistant version, with low smoke, for 600/1000 V. The standard has four categories. F2 means the cable passes the British tests C, W and Z from BS 6387 each on its own: fire, fire with water and fire with mechanical shock. F30, F60 and F120 are the combined test to BS 8491, with fire, impact and water jet at the same time, for 30, 60 or 120 minutes. So F2 is not a 30-minute class.

A BS standard does not replace the CPR. If the cable is permanently installed in a building in the EU, it falls under EN 50575 and the Euroclass in the manufacturer’s declaration of performance counts. The BS standard does not fix that class, and it differs per manufacturer; BS 6724 is offered as Cca, for example. The current ratings come from a different book too. The BS standards refer to BS 7671; a Dutch installation is calculated to NEN 1010.

NEK TS 606 is a Norwegian technical specification for cable on offshore oil and gas installations, fixed and floating. It is published by the Norwegian electrotechnical committee NEK; the current edition is the seventh, from March 2025. The specification builds on the ship standards IEC 60092 and sets stricter requirements for resistance to oil and drilling mud. The name reads layer by layer from the inside out. R is EPR insulation and B fire-resistant with mica tape, F a halogen-free inner sheath, O a copper wire braid and U a halogen-free outer sheath that is resistant to drilling mud. BFOU and BU are the fire-resistant low-voltage types, RFOU and RU are flame-retardant.

Marine cable is something else. It falls under IEC 60092 and needs a type approval from the ship’s classification society, such as Lloyd’s Register, ABS or DNV. Our sheets for offshore cable give no Euroclass, because EN 50575 is about cable in construction works.

For the buyer: order BS and NEK cable by its full designation, with Part and Type for BS 5308 and the category for BS 7846. "BS 7846" without F2 or F120 is not an orderable line, and there is a real difference in fire performance between the two.