BS 6724 Cable: A Comprehensive Guide to LSZH Armoured Cables
BS 6724 is the British Standard for LSZH armoured electrical cables (600/1000V and 1900/3300V). Its LSZH bedding and outer sheath ensure low emissions of smoke and corrosive gases when affected by fire, making them essential for safety-critical applications.
At Cable Services, we are the UK's leading specialist distributor, stocking an extensive range of BS 6724 cables and providing expert support for all your project needs. This guide covers the cable's construction, applications, technical specifications, and key safety benefits.
What Is A BS 6724 Cable & Why Choose LSZH?
What Is A BS 6724 Cable?
A BS 6724 cable is a robust, armoured power cable specified by a British Standard for its high-performance fire safety characteristics, specifically its low emission of smoke and corrosive gases.
The standard applies to thermosetting insulated, armoured cables for fixed installations. Voltage ratings include: Low Voltage (LV): 600/1000V and Medium Voltage (MV): 1900/3300V.
Why Choose A BS 6724 Low Smoke Zero Halogen (LSZH) Cable?
You should choose BS 6724 to significantly enhance safety. Its LSZH properties protect human life by maintaining visibility for evacuation and prevent damage to sensitive equipment.
Three Main Advantages of LSZH:
- Improved Safety for Personnel: Low smoke ensures escape routes remain visible (min. 60% light transmittance). Absence of toxic halogen gases reduces inhalation injuries.
- Protection of Equipment: Eliminates the risk of catastrophic and irreparable corrosion damage to electronics and data servers caused by hydrochloric acid from burning PVC.
- Regulatory Compliance: Ensures adherence to stringent fire safety standards and building codes for fixed installations.
What Is The Construction Of A BS 6724 Cable?
A BS 6724 cable is a multi-layered product, engineered for electrical performance, mechanical strength, and fire safety.
Conductor, Insulation, And LSZH Bedding
- Conductor: Plain annealed stranded copper (Class 2) or solid aluminium (Class 1).
- Insulation: Cross-Linked Polyethylene (XLPE), allowing continuous operation up to +90ยฐC.
- Bedding: LSZH polymeric material that separates the cores from the armour, protecting them from mechanical stress.
Armour: SWA And AWA
The armour provides robust mechanical protection against impact and crushing, making the cable suitable for direct burial.
- Multicore Cables: Use Galvanised Steel Wire Armour (SWA) for tensile strength and impact resistance.
- Single Core Cables: Use Aluminium Wire Armour (AWA).
AWA is used for single core AC cables because it is non-magnetic, preventing the induction of damaging and heat-generating eddy currents.
LSZH Outer Sheath
The final layer is a tough, black outer sheath made from a high-performance LSZH compound. This provides protection against environmental factors (moisture, UV) while delivering the critical low smoke and zero halogen performance that defines the BS 6724 standard.
Where Are BS 6724 Cables Most Commonly Used?
BS 6724 cables are essential in any environment where a fire could pose a significant threat to life or high-value assets.
Key Applications and Risk Profiles
- Public Buildings (Hospitals, Schools, Shopping Centres): High occupancy levels require maintaining clear, smoke-free escape routes.
- Infrastructure (Airports, Tunnels, Underground Railways): Confined spaces where smoke accumulation is dangerous and evacuation is difficult.
- Commercial (Data Centres, Theatres, Control Rooms): High concentration of sensitive electronic equipment that must be protected from corrosive acid gases.
BS 6724 cables are also suitable for general power and control circuits in industrial wiring and mains distribution (indoors or outdoors, clipped or direct burial).
BS 6724 vs BS 5467 & Technical Specs
BS 6724 (LSZH) vs BS 5467 (PVC)
| Feature | BS 6724 | BS 5467 |
|---|---|---|
| Sheath & Bedding Material | LSZH | PVC |
| Smoke Emission (in fire) | Very Low | Dense, Opaque |
| Acid Gas Emission (in fire) | Zero Halogen (<0.5% HCl) | High (Toxic, Corrosive) |
| Primary Application Focus | Public/Safety-Critical | General Industrial/External |
| Insulation | XLPE (90ยฐC) | XLPE (90ยฐC) |
Key Technical Specifications
Voltage & Temperature:
- Voltage Rating: 600/1000V (standard) and 1900/3300V.
- Max Temperature: +90ยฐC continuous conductor operating temperature.
- Installation Temp: Must be above 0ยฐC.
Core Identification:
- 2 Core: Brown, Blue
- 3 Core: Brown, Black, Grey
- 5 Core: Green/Yellow, Blue, Brown, Black, Grey
Relevant Safety Standards And Compliance
BS 6724 performance is verified through rigorous testing against these standards:
- BS 6724: Primary standard for overall construction and performance.
- BS EN 60332-1-2 / 3-24: Tests for flame propagation (flame retardancy).
- BS EN 61034-2: Smoke emission test (verifies low-smoke properties).
- BS EN 60754-1 / 2: Tests for corrosive and acid gas emissions (verifies 'zero halogen').
Your BS 6724 Cable & Accessory Requirements
As the UK's number one specialist distributor, we hold an extensive stock of BS 6724 LSZH cables and all compatible accessories.
We offer a state-of-the-art cable cutting service for custom-cut lengths to eliminate waste and deliver significant cost efficiencies.
For a quote, to check immediate stock, or to discuss your project, contact us today.
Tel: + 44 (0) 1978 340 450 Email: sales@cableservices.co.ukCable Services supply a wide range of products from leading brands, click here to see a sample range of cables that can offer:
Contact Us
For further details on our products and services please get in touch.
Tel: + 44 (0) 1978 340 450
Email: sales@cableservices.co.uk
Cable Cutting Service
We have invested in an automatic winding and measuring cable cutting machine at our Wrexham facility. This ยฃ90,000 investment reflects our commitment to offering an economically valuable and highly efficient service for our valued customers.
We are known for providing tailored solutions that meet the exact needs of our customers. We recognise the growing demand for a flexible service that eradicates waste and delivers cost efficiencies. The efficiency and precision of this new machine support the industryโs commitment to operational sustainability and allow us to pass on cost savings to our customers.
