Low Smoke Zero Halogen Compounds
What does LSZH stand for?
LSZH stands for Low Smoke Zero Halogen and refers to the behavior of chemical compounds when combusted - specifically the quantity of smoke generated and the toxicity of the emissions.
Halogens - What are they?
Halogens are a group of five elements consisting of; Fluorine, Chlorine, Bromine, Iodine, Astatine
Halogens - and the effect of combustion
In their basic form, Halogens are very toxic, strong oxidizers and very chemically reactive. In the event of combustion, LSZH and non LSZH cables behave in very different ways, as indicated below.
What is the difference between LSZH and non LSZH cables?
LSZH cables have a zero Halogen content, emit no toxic fumes, generate very little smoke and produce no corrosive or caustic acids. LSZH cables are therefore suited to areas where fire safety is an important consideration. LSZH cables are also referred to as being non Halogenated meaning, the insulation and sheathing materials do not contain Halogens.
Non LSZH cables, sometimes referred to as Halogenated Cables, are manufactured from compounds that contain Halogens, such as PVC.
On combustion, these compounds generate highly toxic fumes that cause severe irritation to the eyes, nose, mouth, throat and lungs. Increased concentrations are considered fatal to humans.
Furthermore, in the event of fire, large volumes of dense black smoke are produced which block visibility and severely disrupt evacuation procedures. The smoke and fumes can also lead to suffocation from smoke inhalation. A 1 meter length of burning cable that contains 0.85Kg of PVC will completely obscure a room of 1000m3 with black toxic smoke in less than 5 minutes.
In addition, when combusted, Halogens combine with moisture to form Hydrochloric Acid. This extremely corrosive acid is potentially deadly to humans and always causes extensive property damage. Acids of this nature aggressively attack electrical switchboards, motors, fixtures, furnishings, floor coverings, paint surfaces etc. In many cases severe structural deterioration ultimately leads to forced demolition.