BS 5467 vs BS 6724: Which Armoured Cable Do You Need?

Here's a scenario I've seen play out more times than I'd like to count: a project specifies "armoured cable, BS 5467," the procurement team orders it, and the cable gets installed in a basement riser or a public corridor. Everything passes the initial inspection. Then, six months later, a fire safety auditor flags the installation. Why? Because in an enclosed public space, PVC sheathed cable — which BS 5467 calls for — is a genuine life-safety concern.

The thing is, nobody made a mistake on paper. BS 5467 is a perfectly valid standard for armoured power cable. The mistake was using it in the wrong environment. That's what this article is about: understanding the difference between BS 5467 and BS 6724 so you pick the right one the first time.

I'm going to walk you through exactly what each standard specifies, where they overlap, and — more importantly — where they diverge. By the end, you'll know which one belongs in your project spec without second-guessing yourself.

At a Glance: What These Standards Cover

Let's start with what both standards share, because it's actually most of the specification:

See what I mean? For all the practical electrical parameters — conductor, insulation, armouring, current capacity, voltage drop — they're identical. The two cables will perform the same electrically in any circuit. The difference is entirely in the sheathing system, and that's where things get interesting.

The Real Difference: It's All in the Sheathing

If you strip away everything that's the same, the distinction between BS 5467 and BS 6724 comes down to two layers: the bedding (inner sheath beneath the armour) and the outer sheath.

That one material substitution — PVC → LSZH — is the entire difference. But it has massive implications for fire safety.

Fire Performance: PVC vs LSZH

I've had customers tell me "both cables are flame retardant, so what's the big deal?" And they're not wrong — both PVC and LSZH can meet BS EN 60332-1-2 (single wire flame retardance) and even BS EN 60332-3-24 (bunched cable flame retardance, Category C). The difference is what happens while they burn.

The numbers tell a clear story. A PVC-sheathed BS 5467 cable, when burning, fills an enclosed space with dense black smoke — you can't see the exit signs. It releases hydrogen chloride gas, which reacts with moisture in your lungs to form hydrochloric acid. And it produces corrosive gases that can destroy sensitive electronic equipment in adjacent rooms. I've seen a small electrical fire in a server room cause £200,000 in equipment damage — not from the fire itself, but from the PVC cable smoke.

BS 6724's LSZH sheath, on the other hand, produces so little smoke that evacuation routes remain visible. No halogen gases. Minimal acid. The toxicity index is roughly a tenth of PVC's.

Where Each Standard Belongs

This is the part that really matters for specifiers. Here's how I think about it:

BS 5467 — When to Specify It

BS 5467 (CU/XLPE/SWA/PVC) is the workhorse of industrial and utility cabling. It's what you reach for when:

• Underground direct burial — the PVC outer sheath is mechanically robust, UV-stable, and performs well in wet ground conditions. It's extensively used for mains distribution networks.
• Industrial plants and factories — where the fire risk is managed by other means (sprinklers, compartmentation, limited public access).
• External cable runs — between buildings, along fence lines, or in cable ducts where smoke emission is not a concern.
• Substations and utility compounds — limited public occupancy, well-ventilated or outdoor.
• Agricultural and rural installations — cost-sensitive projects where the cable isn't in a habitable building.

Frankly, for outdoor and underground use, BS 5467 is still the sensible default. PVC sheathing is tough, well-understood, field-proven over decades, and more affordable. There's no reason to pay for LSZH if the cable isn't in an enclosed space where people would be exposed to smoke. For a broader comparison of armoured cable types — including SWA vs AWA vs STA constructions — our dedicated guide covers the differences in armour design across both standards.

BS 6724 — When It's Non-Negotiable

BS 6724 (CU/XLPE/SWA/LSZH) exists for one specific reason: life safety. Switch to it when:

• Hospitals and healthcare facilities — patients can't evacuate quickly. Smoke and toxic gas must be minimised.
• Schools, universities, and public buildings — high occupancy, enclosed escape routes.
• Airports, railway stations, and transport hubs — confined spaces with dense crowds. Most transport authorities now mandate LSZH cable throughout.
• Tunnels and underground transit systems — this is arguably the most critical application. In a tunnel fire, smoke is the primary killer, not flames.
• Shopping centres, cinemas, theatres — any space where large numbers of people gather indoors.
• Data centres and control rooms — corrosive HCl gas from PVC fire can destroy server equipment even if the fire itself is contained. BS 6724 prevents that.
• High-rise building risers — smoke can travel vertically through cable shafts, contaminating floors above the fire floor.

The interesting thing about the UK market is that building regulations have been trending toward LSZH for years. Part B of the Building Regulations, BS 9999, and increasingly stringent fire codes are all pushing specifiers toward low-smoke, zero-halogen cables in any building accessible to the public. If you're designing a new commercial building in the UK right now, I'd argue that BS 6724 should be your default unless there's a specific reason to use PVC. Our commercial construction solutions page covers how LSZH cables fit into modern building compliance strategies.

Cable Construction: Side by Side

Let me show you exactly what each cable looks like in cross-section. The construction sequence is identical — the only change is the material of the bedding and outer sheath.

BS 5467 — CU/XLPE/SWA/PVC

1. Conductor: Plain annealed copper, Class 2 stranded (circular up to 25 mm², sector-shaped above).
2. Insulation: XLPE, Type GP8 per BS 7655-1.3. Colour-coded cores.
3. Bedding: PVC, extruded over the laid-up cores to provide a smooth surface for armouring.
4. Armour: Galvanised steel wire (SWA) for multi-core; aluminium wire (AWA) for single-core.
5. Outer Sheath: PVC, Type TM1 per BS 7655-4.1. Black, UV-stable.

BS 6724 — CU/XLPE/SWA/LSZH

1. Conductor: Same — plain annealed copper, Class 2 stranded.
2. Insulation: Same — XLPE, Type GP8.
3. Bedding: LSZH, Type LTS1 per BS 7655.
4. Armour: Same — SWA or AWA.
5. Outer Sheath: LSZH, Type LTS3 per BS 7655. Black, UV-stable.

The dimensional specifications are also identical between the two for equivalent cable sizes. A 4×185 mm² cable to either standard has the same insulation thickness (1.6 mm), bedding thickness (1.4 mm), armour wire diameter (2.5 mm), outer sheath thickness (2.6 mm), and overall diameter (~55–57 mm) — dimensions per BS 5467 / IEC 60502-1. This matters because it means you don't need to re-design cable routing, glanding, or containment when switching between them. If you're still deciding between sheathing materials, our XLPE vs LSZH comparison dives deeper into the material science behind the two sheath types.

The Cost Question: How Much More for BS 6724?

Let's address the elephant in the room. BS 6724 cable costs more. How much more depends on the size and quantity, but you're typically looking at a 15–30% premium over equivalent BS 5467 cable for the LSZH sheathing (market estimate based on UK distributor pricing, 2025–2026).

That sounds like a lot until you consider the total cost of ownership. Here's the thing about saving money on cable sheathing: the cost difference is a one-time saving at the point of purchase. The cost of a fire — in human life, legal liability, business interruption, equipment damage — is potentially unlimited.

I put together a simple comparison for a medium-sized commercial building project (say, 5,000 metres of 4-core 16 mm² armoured power cable):

The installation costs are the same — both cables have identical dimensions and weight, so you use the same cable trays, the same glands, the same pulling equipment. The premium is purely in the raw material cost of LSZH compound versus PVC. And honestly, for the life-safety benefit, I think it's one of the best-value upgrades you can spec on a project.

Standards & Certification: What's Behind the Name

Both standards have been around for decades and are well-established in the UK and markets that follow British Standards. Here's a quick reference table for the associated standards each one references:

If third-party certification matters to your project (and it should), look for cables carrying BASEC or KEMA approval for either standard. Those marks tell you the cable has been independently tested and is routinely audited, not just self-declared by the manufacturer.

How to Tell Them Apart on Site

Here's a practical challenge: both cables look almost identical — black outer sheath, similar diameter, same printed markings. So how do you tell them apart once they're installed?

• Read the cable marking. Every metre of compliant cable should be printed with the standard number. You'll see "BS 5467" or "BS 6724" along with the cable size, voltage rating, and manufacturer details. If the marking doesn't include the standard number, that's a red flag.
• Check for "LSZH" or "Low Smoke" on the sheath. BS 6724 cables are usually marked with "LSZH" or "Low Smoke Zero Halogen" on the outer sheath or binding tape.
• Burn test (small sample). I don't recommend this for installed cable, but on a sample, PVC burns with a green-tinted flame and produces black acrid smoke. LSZH burns with a cleaner flame and produces very little smoke. The smell is different too — PVC smells like chlorine; LSZH doesn't.
• Ask for the certificate. Insist on a batch test certificate showing compliance with the relevant fire tests (smoke density, halogen content) if BS 6724 is specified.

SORIVO's Quality Commitment

Whether you need BS 5467 or BS 6724, the quality of the cable itself matters just as much as choosing the right standard. Here's what we do differently:

Quick Decision Checklist: Which Standard for Your Project?

Use this checklist before you write your cable specification. Answer three questions:

So Which One Do You Need?

Here's my straightforward take, and I don't think this is controversial:

• If the cable runs underground, outdoors, in a well-ventilated industrial area, or anywhere a fire won't expose people to the smoke — BS 5467 (PVC) is perfectly adequate and more cost-effective.
• If the cable runs indoors, in a public building, in an enclosed escape route, in a tunnel, or anywhere people would be exposed to smoke in a fire — specify BS 6724 (LSZH). It's not just better practice; in many jurisdictions it's now a regulatory requirement.

And if you're not sure? When in doubt, go with BS 6724. The 15–30% material premium is a small price for the peace of mind that comes from knowing your cable won't contribute to smoke inhalation deaths or equipment damage in a fire. I've never met a specifier who regretted choosing LSZH. I've met plenty who regretted not choosing it.

At Sorivo, we manufacture both standards to full third-party certification standards. Every cable is metre-marked, batch-traceable, and tested before it leaves our factory.

Frequently Asked Questions

Reviewed by Luo Qiang — Senior Cable Application Engineer, Sorivo
15+ years in industrial and renewable energy cable specification. Member of IEC TC 20 (Power Cables). Previously contributed to cable selection for 500MW+ solar PV and BESS projects across Asia, Europe, and the Middle East.