What's the difference between PVC and LSZH cables?

When you need to buy bulk cable or cable assemblies, you're probably concerned about things like conductor AWG size, shielding for EMI/RFI, connector molding construction, gold plating on the connectors and, ultimately, will the signal get from point A to point B quickly and with minimum loss or distortion. That's a lot of factors to think about! So why would you spare a thought to the jacket that just goes around the conductors?

It turns out that the cable jacket can be much more important than you may think. Choosing the wrong cable jacket type can have implications in a range of things, from extending the life of your cable, to using the cable in the field, to basic health and safety.

Physical difference:

PVC and LSZH are very different. PVC patch cords are very soft; LSZH patch cords are more rigid because they contain the flame retardant compound, and they are aesthetically more pleasing.

PVC and LSZH Cable Fire Tests

A PVC cable (made of polyvinyl chloride) has a jacket that gives off heavy black smoke, hydrochloric acid, and other toxic gases when it burns. 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 smoke and fumes emitted by PVC cable is toxic and corrosive and detrimental to your health.

LSZH cable 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. LSZH cable does have some restrictions. According to CENELEC standards EN50167, 50168, 50169, screened cables must be halogen free. However, no similar regulation yet applies to unscreened cables.

PVC and LSZH Cable Applications:

Whether you choose PVC or LSZH jacket depends on where you're going to run the cable. PVC cable is commonly used for horizontal runs from the wiring center. You can use it for vertical runs between the floors - but only if the building features a contained ventilation system running through the duct work. 

LSZH cable is used between floors in a building. It has a special flame-retardant coating. A plenum is a space within the building created by building components, designed for the movement of environmental air. 

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