Knowledge on Cable Flame Retardancy: A Brief Introduction

This article covers cable flame retardant testing and related knowledge of sheathing materials. The single-root vertical combustion test is for scattered wiring scenarios in households, while the bundled combustion test is for dense wiring scenarios in subways. The flame retardant performance of cable sheathing materials is related to comprehensive properties such as resistance to scratching and UV protection. When choosing cables, one must consider the flame retardant grade, scenario requirements, and the comprehensive performance of the sheathing materials.

Q1: How is the flame retardancy level of cable sheaths classified? What does a higher level indicate?

A: Commonly, it is divided into ordinary flame retardancy, bundled C, B, and A classes. The higher the level, the stronger the ability to inhibit flame spread, suppress smoke, and resist molten droplets. It is more suitable for high-risk places with dense, enclosed, and crowded people.

Q2: Are flame-retardant cables completely non-combustible?

A: No. Flame-retardant materials are difficult to ignite, extinguish on their own when away from the fire, and do not spread. Even in a continuous fire, they will still be damaged. The core function is to prevent the fire from spreading, rather than being absolutely non-combustible.

Q3: Is cable flame retardancy the same as fire resistance? What are the differences?

A: Completely different.

• Flame retardant: Does not spread when on fire, extinguishes on its own when away from the fire, focuses on preventing the fire from expanding;

• Fire resistance: Maintains power supply for a certain period of time under high-temperature fire conditions, ensuring continuous power supply for fire alarms, emergency lighting, and escape routes.

Q4: Will environmental temperature and humidity affect the flame retardancy effect of cable sheaths?

A: Yes. Humidity, high temperature, aging, oil contamination corrosion will damage the structure of the flame retardant additives. After long-term aging, the flame retardant performance will decline. Qualified modified sheath materials can withstand humidity and aging, and have stable performance over the long term.