BS EN 50525-3-41 Cable

What the Standard Is?

Cleveland Cable Company is the UK's largest stockist of BS EN 50525-3-41 cable - the UK implementation of the EN 50525-3-41 standard for low-voltage, halogen-free, single-core cables for fixed wiring.

In practical terms, "BS EN 50525-3-41 cable" usually refers to low-smoke zero-halogen (LSZH) single-core power cable used for fixed installation, typically with:

Voltage rating of 450/750 V
LSZH insulation (low smoke, zero halogen)
Copper conductors (solid or stranded, depending on type)

Historically, LSZH singles were commonly specified to BS 7211. For many LSZH single-core products (such as 2491B / 6701B), BS EN 50525-3-41 is now treated as the current reference standard in the UK. Always check your project specification to confirm whether BS 7211 or BS EN 50525-3-41 is called up.

Why It Matters for Cable Selection

Choosing a cable that complies with BS EN 50525-3-41 is primarily about fire safety and compliance:

Compared with standard PVC cable (for example 6491X or H07V-R under other parts of BS EN 50525), LSZH cable releases far less smoke and virtually no corrosive halogen gases when exposed to fire.
This can significantly improve visibility and reduce toxic fumes in escape routes and confined spaces, helping occupants and first responders.

From a purchasing perspective, specifying "BS EN 50525-3-41" makes it clear you require:

LSZH insulation rather than standard PVC
A harmonised, recognised standard for low-voltage fixed wiring
A cable suitable for 450/750 V applications

Cables That Comply with BS EN 50525-3-41

H07Z-R (6491B)

H07Z-R is a key harmonised cable type within BS EN 50525-3-41. It is:

A 450/750 V LSZH-insulated single-core cable
Manufactured with stranded copper conductors (Class 2)
Designed for fixed wiring in conduits, trunking and distribution boards

In the UK, H07Z-R is commonly branded and sold under designations such as 6491B (for 450/750 V). These cables are widely used as LSZH alternatives to standard PVC 6491X (H07V-R) type wire.

H07Z-K (2491B/6701B)

In the UK market:

2491B/6701B is a well-known trade designation for flexible LSZH single-core cable with Class 5 fine-stranded copper conductors, associated with H07Z-K and BS EN 50525-3-41. The cable is referred to as 2491B when the conductor size is between 0.75 mm² and 6 mm². The cable is referred to as 6701B when the conductor size is 10 mm² or above.

Both are widely used in building services and infrastructure projects that require BS EN 50525-3-41-type performance (low smoke, zero halogen) rather than standard PVC.

What Do H07Z-R, H07Z-K and H07Z-U Designations Mean?

The harmonised cable designations identify the voltage rating, insulation type and conductor construction:

H: Harmonised European standard.
07: Rated voltage of 450/750 V.
Z: Halogen-free, low-smoke insulation compound.
-U: Class 1 solid copper conductor (single wire).
-R: Class 2 stranded copper conductor.
-K: Class 5 flexible, fine-stranded copper conductor.

Applications and Selection Context

Typical Installation Environments

BS EN 50525-3-41 cables, such as H07Z-R, 2491B and 6701B, are used as fixed wiring power cables and control wires in:

Distribution boards, switchgear and control panels
Conduits, trunking, cable trays and containment systems
Public buildings: offices, hospitals, schools, airports and shopping centres
Transport and infrastructure: stations, tunnels, underground car parks, rail and metro systems
High-occupancy or high-value facilities where fire performance is critical

They are not appliance flexes like H03VV-F or H05VV-F (which are flexible PVC cables under BS EN 50525-2-11 for connecting appliances). Instead, BS EN 50525-3-41 focuses on fixed wiring where consistent LSZH performance throughout the installation is required.

When to Choose Halogen-Free Cables

You should choose BS EN 50525-3-41 LSZH cables instead of standard PVC singles when:

The specification or local regulations explicitly call for "LSZH", "LZOH", "LSF" or similar wording
The installation is in escape routes, stairwells, corridors or confined spaces where smoke density and toxic fumes are a major concern
The project is a public or critical facility (data centres, hospitals, rail, tunnels or high-rise buildings) where business continuity and life safety are paramount
Corrosive gases from burning PVC could cause excessive damage to equipment, structures or sensitive electronics

While LSZH cables usually cost more than PVC, they offer risk reduction, easier approvals and a stronger safety case - key factors for specifiers and technical buyers managing compliance and liability.