What Is Low Smoke Zero Halogen (LSZH) Cable? Benefits, Applications, and Safety Guide

In the world of cables and wiring, Low Smoke Zero Halogen (LSZH) — also called Low Smoke Halogen-Free (LSHF) or Low Smoke Zero Halogen (LSOH) — refers to the type of material used for the cable's jacket or insulation. LSZH cables are designed to produce minimal smoke and no toxic halogen gases when exposed to fire, making them a safer choice for human health and sensitive equipment.

■ Understanding LSZH: The Basics

LSZH cables use thermoplastic or thermoset compounds that do not contain halogens such as chlorine, fluorine, bromine, or iodine. These halogens, when burned, can produce toxic and corrosive gases that harm people and damage electronics.

When LSZH cables catch fire, they:

• Emit very low smoke, improving visibility for evacuation.

• Release non-toxic gases, reducing risks of inhalation injuries.

• Produce non-corrosive residues, which protect sensitive equipment.

■ Why Is LSZH Important?

1. Safety in Fire Emergencies

In enclosed spaces like subways, tunnels, offices, ships, and data centers, traditional PVC cables can release thick black smoke and toxic fumes during a fire, making evacuation and rescue difficult. LSZH cables greatly reduce these risks.

2. Protection of Equipment

Halogen gases are corrosive to metals and electronics. In critical infrastructure, LSZH cables help prevent damage to servers, control systems, and telecom equipment during a fire.

3. Compliance with Safety Regulations

Many countries and industries mandate LSZH cables in specific environments — especially public transportation, hospitals, and offshore facilities.

■ Typical Applications of LSZH Cables

• Railway and subway systems

• Airports and aircraft wiring

• Hospitals and medical facilities

• Ships and offshore oil platforms

• Data centers and server rooms

• Public event venues

• Tunnels and underground facilities

■ LSZH Standards and Certifications

LSZH materials are tested according to international standards such as:

• IEC 60754 – Tests for halogen acid gas content

• IEC 61034 – Measurement of smoke density

• EN 50267 & EN 50268 – Low smoke emission standards

• UL 1685 – Vertical-tray fire propagation and smoke test

■ Q&A: Everything You Need to Know About LSZH Cables

Q1: Is LSZH the same as plenum-rated cable?

A: No. Plenum-rated cables are designed for use in air-handling spaces and meet strict flame-spread and smoke requirements, but they may still contain halogens. LSZH focuses specifically on low smoke and zero halogen emissions.

Q2: Are LSZH cables less durable than PVC?

A: LSZH cables can be slightly less flexible than PVC due to the different compound composition, but they are highly durable for most industrial and commercial uses.

Q3: Can LSZH cables be used outdoors?

A: Yes, but only if they are UV-resistant and weather-rated. Many LSZH cables are designed for indoor use unless specified for outdoor applications.

Q4: Why are LSZH cables more expensive?

A: The special materials and manufacturing process make LSZH cables costlier, but the safety benefits often outweigh the price difference.

Q5: Do all safety codes require LSZH cables?

A: Not all. Requirements depend on the region, building type, and industry standards.

■ Final Thoughts

Low Smoke Zero Halogen cables are becoming the preferred choice in safety-critical environments, where protecting lives and equipment during a fire is a top priority. While they may cost more than PVC cables, their benefits in reducing smoke, toxicity, and corrosion make them invaluable for modern infrastructure.

If you're selecting cables for public spaces, transport systems, or sensitive electronic installations, LSZH is a smart investment in safety and compliance.