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LSZH (Low Smoke Zero Halogen) and PVC cables

LSZH and PVC cables

The European market is demanding that cables used in LANs, WANs, etc. meet LSZH specification. The IEC 60332-1 governs the Flame Retardant Grade specifications in reference to LSZH cables.

Reduction of dangerous/poisonous gases

Essentially, the compound used in manufacturing cables meeting the above specification reduces the amount of dangerous/poisonous gases in case of fire. The main difference in specifications between IEC 60332-1 versus UL® 1581, UL 1666 and UL 910 is that the cable under the IEC spec can continue to burn while still emitting very low gases. The UL specs demand that the flame be extinguished, but it can still emit dangerous/poisonous gases.

IEC specification

Today virtually all medium and large installations in Europe must meet the IEC specification. Many public authorities are already demanding that new installations must meet IEC 60332-3 which is a more demanding flammability specification for LSZH. IEC 61034 for smoke emission is part of all Black Box LSZH bulk cables.

What's the difference between PVC and LSZH cables

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

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. Low Smoke Zero Halogen (LSZH) cable has a flame-resistant jacket that doesn't emit toxic fumes even if it burns.

LSZH more expensive and less flexible

LSZH cables usually cost more than the equivalent PVC cable, and certain types are less flexible. 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.

Where do you run the cable?
Whether you choose a riser (PVC), plenum or LSZH jacket depends on where you're going to run the cable.

PVC cable is commonly used for horizontal runs from the wiring centre. 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.

Building showing Plenum and riser cable

Building showing plenum cable (red) and riser cable (blue).

Learn more: Solid vs Stranded Patch cables
More about Copper Cable standards: CAT3 and CAT4 cables