Friday, June 15, 2012

What the heck is LSZH Wire and Cable?

So you've been doing wiring for some time now and you come across a job walk that specifies the installation of LSZH or maybe you need to match some cable at your location that is LSZH specified. Lets check out what is LSZH, where to install it and pros and cons.

LSZH stands for Low Smoke Zero Halogen. The cable jacket and insulation is made with some very special materials. In case this type of cable is ever involved in a fire very little smoke is produced making this cable an excellent choice for confined places with lots of people.

I know the LS part is easily understood but what about the ZH? The zero halogen, what is that? Halogens are elements such as bromine, chlorine and fluorine. Halogens are very highly reactive and hurt people and animals. PVC wire and cable has a huge amount of halogens in it. The C stands for chloride and typically this cable on average contains 29% by weight. Teflon, FPE and PTFE contain up to 76% of fluorine. Halogens in LSZH materials are under 1%

Another concern is when cable is burned and toxic gases are released into the air they can also be harmful when mixed with water. So when that sprinkler system turns on you've now created toxic acids.

The number one cause of death related to fires is smoke inhalation. An estimated 70% of fire deaths are a result of smoke inhalation rather than burns. Smoke Inhalation occurs when products of combustion are breath in during a fire. Damages to the body are by simple asphyxiation (lack of oxygen), chemical irritation, chemical asphyxiation or a combination of all these.

Now that you have a quick understanding of LSZH what are the Pros and Cons of the cable?

PRO: LSZH produces less smoke when burned allowing for more time to exit.

CON: LSZH is more susceptible to jacket cracking. Special lubricants have been made to minimize damage during installation.

PRO: Because little or no halogen gas is released less damage to the respiratory is done and less corrosion damage is done to equipment near the fire.

CON: LSZH jacket has a high filler content, around 50% to provide the required flame and smoke performance. This results in a lower mechanical, chemical resistance, water absorption and electrical properties then non LSZH compounds.

PRO: The jacket of LSZH cable has a lower coefficient of friction making installation easier.

CON: The current generation of LSZH cables has not yet established a proven history of long time performance.

In one of our YOUTUBE videos a LSZH fiber cable is shown. Its hard to tell the difference just looking at it but off camera I did notice once stripped that the jacket buckled and cracked when flexing it.

Questions? Comment below!

"By Mercy Salinas"