Copper cable sheath - PVC or LSZH?

In today’s cable installations you will find 2 main types of cable sheath used for network cables, PVC (polyvinyl chloride) or LSZH (Low Smoke Zero Halogen).

In fact, when it comes to data or LAN cabling, most will ultimately look at the cable performance when deciding on whether to install CAT5E, CAT6 or CAT6A LAN cable.

One factor that is often overlooked when choosing an installation cable is its outer sheath.

The outer cable sheath is very important as it protects the internal copper pairs from damage and acts as an insulator from external interference.

However, when deciding on whether to use PVC or LSZH cable an important consideration should be how it will react in the event of a fire. The health and safety of individuals should always be the most important and deciding factor.

Today virtually all medium and large installations in Australia and throughout the world are becoming more conscious of fire safety for existing and new building constructions. Local building standards and fire safety codes are also placing more stringent requirements on fire safety. In addition, many carrier and data centre networks are specifying that only LSZH cables are used within the confines of an Telecom Exchange or Data centre.

Low smoke zero halogen cable is becoming very popular and, in some cases, a requirement where the protection of people and equipment from toxic and corrosive gas is critical.

Though LSZH or PVC cables may look identical on the outside there are number of key distinguishing factors between the 2 types.

PVC cables are softer and less rigid than LSZH cables and are therefore easier to handle. LSZH cables are more rigid or firm because they contain a flame retardant compound. In addition, LSZH cables, whether they are work area patchcords or backbone and horizontal cabling are generally a little more expensive.

Choosing the wrong cable jacket type can have implications in a range of things, from extending the life of your cable, to basic health and safety.

In most cases, a PVC jacket will be fine to use as a patch cord or for single in-wall runs. However, when you have many cables running in a confined space, like a Plenum area of an office building or within risers, there are a couple of dangers with using PVC jackets.

The first danger with fire is the potential for the fire to leap from one room or level to the other.  In a typical building, one of the first defences when a fire breaks out is to control the fire and stop it from quickly spreading.

PVC cable jackets burn very easily and fire can easily spread from room to room or from floor to floor simply by burning along the cables.

The other danger is that PVC releases hazardous gasses when it burns.  If the fire was to spread or break out in an office or an area with people, the smoke and fumes emitted by PVC cable is toxic and corrosive and detrimental to your health.

One of the main benefits with LSZH (Low smoke zero halogen) cable is that it has a flame-resistant jacket that doesn’t emit toxic fumes even if it burns. This reduces the amount of toxic and corrosive gas emitted during combustion.

In addition, a good LSZH cable will also be self extinguishing to a certain point and will also help stop the fire from spreading.

When choosing work area patch cords or LAN cable and regardless of whether CAT5E, CAT6 or CAT6A cable is being installed it is always important to think about what cable sheath type you require and to think of the potential risks associated with that decision. Always check your building fire safety requirements and make an informed decision in order to minimise risks.

Warren and Brown offers both PVC and LSZH copper cable options for in building use in CAT6 and CAT6A, however we do recommend using LSZH wherever possible.