If you read a few tenders or talk to enough integrators, you quickly notice the same pattern. One project asks for “Cat6 LSZH”, the next calls for “CMR Cat6”, and a third simply says “PVC jacket”. Online listings add their own mix: CM/LSZH, RoHS, “low smoke”, “plenum style” and so on, often in the same title. It is not always clear what is a real requirement and what is just marketing language.

This article does not try to turn you into a fire engineer. The goal is more modest: give system integrators, consultants and IT managers a grounded understanding of what PVC and LSZH Ethernet cable jackets actually are, how they relate to labels like CM/CMR/CMP, and how to decide where each type makes sense in everyday SMB and campus projects.

We will stay focused on copper structured cabling for offices, schools, hospitals and small data rooms. Fibre has its own jacket ratings such as OFNR and OFNP, which we cover in a separate guide on fibre optic cable types and jacket ratings .

1. What PVC and LSZH jackets actually are

On a basic level, the outer jacket of an Ethernet cable is just that: a protective sheath around the insulated conductors. It needs to be tough enough to survive installation, flexible enough to route through pathways and stable enough to live in ceilings and walls for many years. How it behaves in a fire, however, is strongly influenced by the jacket material.

PVC, or polyvinyl chloride, is the traditional choice for many network cables. It is easy to process, relatively inexpensive and well understood by manufacturers. The downside is its behaviour when it burns. PVC can produce dense smoke and corrosive, halogen-containing gases. In a confined space, that smoke can obscure exits and damage sensitive electronics even if the flames themselves never reach them.

LSZH stands for “low smoke zero halogen”. The jacket is formulated without halogenated additives, so it does not release chlorine or similar corrosive gases when exposed to fire. It also produces significantly less smoke than a comparable PVC jacket. In a building with many occupants or a room packed with equipment, that difference matters: people can see exits for longer, and the air is less aggressive to hardware and infrastructure.

From an electrical point of view, both PVC and LSZH network cables can meet the same Cat5e, Cat6 or Cat6A performance requirements. The difference is not bandwidth; it is what happens in those rare but critical minutes when something goes wrong.

2. CM, CMR and CMP – how fire ratings fit into the picture

CM, CMR and CMP are often mentioned in the same sentence as PVC and LSZH, which makes it feel as if they are competing labels. They are not. CM/CMR/CMP are installation ratings defined by North American fire codes, while PVC and LSZH describe jacket materials. They intersect, but they are not the same thing.

In very simplified terms, CM covers general-purpose use, CMR covers risers and vertical shafts, and CMP covers plenum spaces such as air handling voids. Each step up the ladder requires the cable to behave better under fire test conditions. A CMP cable has to meet stricter smoke and flame spread limits than a CM cable.

Many CMP cables are, in practice, formulated with low-smoke, low-toxicity jackets, but not every CMP cable is automatically LSZH, and not every LSZH cable is CMP. Outside North America, local standards often focus more directly on the materials and smoke characteristics – asking for LSZH in particular spaces – rather than using the CM/CMR/CMP naming.

For most SMB networks operating outside strict North American plenum rules, you can think about it like this: fire ratings tell you where a cable is allowed to go, and jacket materials tell you how it behaves if something burns. They are both part of the safety story, but they talk about different aspects.

3. Where LSZH makes the most difference

If budget were unlimited, you could simply specify LSZH for everything and never think about it again. In reality, projects balance safety, regulations and cost. That means deciding which spaces win the most from LSZH, and where a well-chosen PVC cable is still a reasonable choice under local code.

In open-plan office floors, many installs still use PVC network cables, especially in regions without strict low-smoke requirements. The fire load is spread out, ceilings are relatively open and evacuation routes are short. In these spaces, LSZH is often a “nice plus” rather than a hard requirement, unless client policy or building guidelines say otherwise.

In data rooms, server rooms and dense wiring closets, the calculus changes. You often have large volumes of cable in limited space, plenty of power and equipment that is sensitive to corrosive smoke. Here LSZH jackets offer real protection to both people and hardware. A small incident that fills a room with thick, acidic smoke can be far more damaging than the fire itself.

Schools, hospitals and public buildings sit in a similar category. Evacuating many people from complex layouts takes time, and there may be occupants who cannot move quickly on their own. Limiting smoke density and toxicity is a straightforward way to buy extra minutes and visibility. That is one reason LSZH has become steadily more common in education and healthcare specifications.

If you are unsure whether local regulations or building policies prefer LSZH in certain areas, the safest path is to check with the client’s safety officer or building engineer before finalising the bill of materials.

4. Can PVC and LSZH coexist in the same project?

In practice, many real-world projects end up with a mix of jacket types. That is not inherently a problem, provided the mix is deliberate and documented. For example, a campus might use LSZH cables in main data rooms, risers and critical spaces, and PVC in small office fit-outs where regulations are lighter and cable volumes are modest.

If you do take that approach, it is worth making the boundaries explicit. Floorplans, cable schedules and labelling should make it obvious where LSZH is installed and where PVC is used. This helps future teams avoid accidentally extending a riser or equipment-room run with a cheaper cable that does not meet the original safety intent.

Electrically, mixing jacket types does not change the Cat6 or Cat6A performance of a link if the underlying copper and construction are correct. The signal does not “know” whether it is travelling through PVC or LSZH. What matters is whether the cable remains compliant with the performance and safety assumptions of the environment it is installed in.

5. Installation and handling: is LSZH really harder to work with?

Older generations of LSZH cable had a reputation for being stiffer or more brittle than PVC, especially in cold conditions. Installers sometimes found that jackets nicked or cracked more easily if pulled aggressively around tight corners. That experience still colours people’s expectations.

Modern LSZH formulations are generally more installer-friendly, but they can still feel different from PVC. They may have a slightly higher stiffness or less “rubbery” feel. In return, you get significantly better smoke behaviour. For most structured cabling work – pulling through trays, baskets and conduit with sensible bend radii – the differences are manageable with normal good practices.

The bigger risk is treating the jacket like an afterthought. Long before you choose PVC or LSZH, you should already be looking at bend radius, support spacing, pathway fill and separation from power. Those basics have a much larger impact on long-term network performance than the jacket material alone. If you need a refresher on how mechanical stress translates into electrical performance, our article on bend radius and return loss goes through the main points.

6. How to write PVC/LSZH requirements into a spec

When a requirement for LSZH appears in a tender, it often shows up as a short line buried in many pages of text. Conversely, some projects never mention the jacket material at all. Both extremes make life harder for integrators and clients, because they encourage guesswork.

A clearer way is to write requirements per area. For example, “All horizontal Cat6A cabling in data rooms, risers and critical escape routes shall be LSZH jacketed,” or “Office floor horizontal cabling may be PVC or LSZH, provided local code is met.” This leaves room for sensible value engineering without blurring genuinely important safety choices.

On the Ethernet side, PVC and LSZH jackets can both sit on top of solid copper conductors and the same performance geometry. What you do not want is an unverified cable that mixes an attractive jacket label with poor materials elsewhere, such as copper-clad aluminium conductors. If in doubt, be more suspicious of a price that looks too good to be true than of a particular material name.

7. How AMPCOM approaches PVC and LSZH jackets

From a manufacturer’s perspective, the aim is to give integrators a small, reliable set of options rather than a confusing catalogue. AMPCOM focuses on solid copper Cat5e, Cat6 and Cat6A network cables with either PVC or LSZH outer jackets, designed for the kinds of SMB offices, campuses and data rooms described in this article.

In spaces where low smoke and halogen-free behaviour are a clear benefit – data rooms, wiring closets, classrooms, critical offices – LSZH jackets are often a sensible default. In more conventional office areas under less strict local requirements, PVC remains a common choice. The right answer for any given project depends on local code and the client’s risk appetite, not on marketing terms alone.

If you are planning a broader refresh of your cabling, and want to see how jacket choices fit into the bigger picture of pathways, rooms and subsystems, our introduction to structured cabling for SMB and campus networks offers a useful wider context.

FAQ: PVC vs LSZH Ethernet Cable Jackets

Is LSZH always better than PVC for Ethernet cabling?

LSZH is better in terms of smoke density and halogen gas release during a fire, which matters a lot in enclosed or high-occupancy spaces. That does not mean it is automatically the best or only choice everywhere. In some office environments, local code may not require LSZH, and cost or existing standards may favour PVC. The “better” material is the one that matches the safety expectations and regulations of the space, not simply the one with the most impressive label.

Can I mix PVC and LSZH network cables in the same building?

Yes, as long as the mix is intentional, compliant with local rules and properly documented. Many real projects use LSZH in data rooms, risers and critical areas, with PVC in less demanding spaces. Make sure drawings and records clearly show where each jacket type is installed so future changes do not accidentally weaken your original safety assumptions. Electrically, mixing jacket types does not harm Cat6 or Cat6A performance when the cables are well made.

Do LSZH Ethernet cables have the same performance as PVC cables?

From a category performance point of view, yes. Both PVC and LSZH network cables can meet Cat5e, Cat6 or Cat6A requirements for insertion loss, crosstalk and return loss when properly designed and manufactured. The main differences are mechanical feel and fire behaviour, not bandwidth. As always, conductor material and construction quality matter more than the jacket label; a well-made LSZH or PVC cable will outperform a poorly made one of any type.

What does “CM/LSZH” mean in some cable descriptions?

When you see “CM/LSZH” or similar combinations in marketing text, it usually means the cable has a general-purpose CM fire rating and uses an LSZH jacket material. The CM part refers to where the cable is permitted to be installed under North American style codes, and LSZH refers to how the jacket behaves in a fire. Always check the datasheet or print on the cable itself rather than relying solely on a short product title.

When should I definitely consider LSZH for my SMB or campus network?

LSZH is particularly worth considering in spaces where smoke and corrosive gases would be especially harmful: data rooms with high equipment density, core wiring closets, classrooms, healthcare areas, escape routes and any other location where evacuation might be slow. In those spaces, the difference between a low-smoke, halogen-free jacket and a standard PVC jacket become more than a theoretical detail; it can influence both safety and recovery after an incident.