Difference between FRZH & FRLS House Wires

With the increasing demand for public safety, Electrical contractors have already started seeking out FRZH & FRLS House wires. FRLS stands for Flame Retardant Low Smoke and FRZH Stands for Flame Retardant Zero Halogen

Both the House Wires are largely made of the same composite called Thermoplastic, meaning they become liquids when exposed to flame or high temperatures.

Here’s a Quick Comparison Chart of Normal PVC wires against FRLZ & FRZH:


Image credit: Polycab

As you can see, the Normal PVC wires just don’t stand a chance in the argument of public safety.  So, we ain’t going to talk about it.

Back to topic.

The terms ‘Zero Halogen’ & ‘Low Smoke’ in FRZH & FRLS are two distinct properties of compounds. Low Smoke describes the amount of smoke the wires would cause when subjected to flames, while Zero Halogen describes that it doesn’t contain any of chemical elements defined as a halogen.

These wires have different properties and slightly different uses since they typically go hand in hand in LSZH Wires. The point being here is that the house wires can be zero halogens and not low smoke and vice versa.

If you are stuck between FRZH and FRLS on your next project and not sure which type of house wires to use, read on to find out which one would be most appropriate for your plans.

Below are some properties of FRZH House Wires:

  • Insulated with EVA based halogen-free compound
  • Rubber-like softness & flexibility
  • Near absence of smoke, toxic fumes and corrosive gases in the event of fire
  • Small amount of smoke with 20% density
  • Highly fire-resistant, burns without flame and negligible non-toxic smoke
  • Recommended being used where a large congregation of people are expected like hotels, theaters, multiplexes, shopping malls, metro railways, hospitals, schools, commercial complexes and high-rise residential buildings

Below are some properties of FRLS House Wires:

  • Insulated with PVC for better resistance in higher temperature
  • Tough, sturdy & flexible
  • Less toxic smoke generated in case of fire
  • Minimum 29% low smoke density
  • Mildly fire resistant, delays fire action, burns slowly
  • Economical compared to FRZH
  • Recommended being used in premium quality constructions like hotels, hospitals, schools, commercial complexes, residential apartments and so on.

Another type of wire, you would often come across is LSZH (Low smoke zero halogens). Such type of wires doesn’t burn and melt easily. Smoke level is almost to nothing, transparent, and non-toxic. LSZH is used in applications where important circuits are supposed to keep running in the event of fire outbreak.

There you have the difference between two of most useful insulation materials used in House Wires.  Although many other types of insulation materials are available out there in the market, which we will cover in our next post. So, stay tuned!

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