In the world of cables, "fire safety" is of paramount importance. When we talk about fireproof cables, we often hear the terms "flame retardant" and "fire resistant." They sound similar, but they actually represent two fundamentally different functions and applications. Confusing them can not only increase project costs but, more critically, may create fatal safety hazards in the event of a fire.

Today, we'll precisely and accurately analyze the essential differences between flame retardant and fire resistant cables, based on their structure, materials, cost, IEC testing standards, and applications. This guide will help you make the most professional selection decisions.

1. Core Function and Operating Principle: Survival vs. Sustaining

This is the fundamental key to understanding the difference.

l Flame Retardant Cable: Its core function is to prevent or slow down the spread of flames. When the cable catches fire, it can contain the flame within a certain area and self-extinguish once the fire source is removed. However, a flame retardant cable will lose its power supply function when the fire continues to burn.

nOperating Principle: This is achieved by adding a large amount of flame retardant to the insulation and sheath materials (such as halogen or non-halogen flame retardants). These additives decompose at high temperatures, releasing non-combustible gases or forming a dense carbonized layer that isolates oxygen, thereby achieving the flame retardant effect.

l Fire Resistant Cable: Its core function is to maintain normal operation for a certain period during a fire. Even when the cable is engulfed in flames, it can preserve the integrity of the circuit, continuing to transmit power or signals to critical systems like fire-fighting equipment, emergency lighting, and evacuation systems, providing valuable time for evacuation.

n Operating Principle: Fire resistant cables typically contain one or more layers of mica tape. Mica is a naturally high-temperature-resistant mineral that does not burn at high temperatures. It forms a solid "skeleton" or "fire barrier," isolating the conductor from the external flame and ensuring the circuit continues to function during a fire.

Simply put: A flame retardant cable "protects itself" to prevent the fire from spreading; a fire resistant cable "protects others" by ensuring critical equipment continues to operate during a fire.

2. Structure and Materials: The Critical Difference is Mica Tape

The structural differences between the two are a direct reflection of their distinct functions.

l Structure of Flame Retardant Cables:

Conductor → Flame Retardant Insulation → Flame Retardant Sheath.

Some higher-grade flame retardant cables might have a flame-retardant filler between the insulation and sheath.

The key feature is that the insulation and sheath materials themselves are flame retardant, but they do not contain mica tape.

l Structure of Fire Resistant Cables:

Conductor → Fire Resistant Layer (core is mica tape) → Flame Retardant Insulation → Flame Retardant Sheath.

The insulation and sheath of fire resistant cables are also typically flame retardant to prevent the spread of fire.

The signature structure is the mica tape tightly wrapped around the conductor, which is the guarantee of its fire-resistant performance.

3. IEC Testing Standards and Classification: A Strict and Precise Distinction

The International Electrotechnical Commission (IEC) standards are the authoritative basis for distinguishing between the performance of these two types of cables.

l Testing Standards and Classification for Flame Retardant Cables:

Primarily based on the IEC 60332 series of standards.

IEC 60332-1-2: Single vertical insulated wire and cable flame test. This is the minimum flame retardant requirement, testing the performance of a single cable.

IEC 60332-3: Vertical flame spread test on a bunched wire and cable. This is a higher-level requirement that simulates a densely laid cable environment, testing whether flames will spread along the cable bundle. According to the volume of non-metallic material, it is divided into different categories, such as A, B, C, and D, with Category A having the best flame retardant performance.

l Testing Standards and Classification for Fire Resistant Cables:

Primarily based on the IEC 60331 series of standards.

IEC 60331: Test for fire resistance of cables required to maintain circuit integrity under fire conditions. This tests the cable's ability to continue supplying power when subjected to a direct flame (750℃ or higher), and it specifies a particular fire-resistant time, such as 90 minutes or 120 minutes.

For example, a cable that passes IEC 60331-21 must maintain power for 90 minutes without interruption under a 750℃ flame.

Fire resistant cables typically must also meet the flame retardant requirements of IEC 60332-3 to ensure they prevent flame spread in areas not directly exposed to the core fire.

4. Price and Cost: Performance Dictates Price

l Flame Retardant Cables:

Since they only require the addition of flame retardants to the material formulation, their cost increase is relatively limited.

The price is typically 10%-30% higher than ordinary cables, depending on the flame retardant grade.

They are the most widely used type of fire-safety cable.

l Fire Resistant Cables:

Due to their complex structure (especially the expensive high-temperature mica tape) and stringent manufacturing processes, their cost is significantly higher than flame retardant cables.

The price is usually 2-3 times that of a flame retardant cable of the same specification.

They are considered specialized functional cables and are generally only used in critical circuits.

5. Application Scenarios and Selection Advice: The Right Tool for the Job Ensures Safety

l Selection Advice for Flame Retardant Cables:

Application Scenarios: All locations that require prevention of flame spread, such as residential buildings, commercial buildings, and industrial plants.

Key Principle: Where cables are installed, priority should be given to flame retardant cables, especially in dense cable areas and places with high pedestrian traffic.

Grade Selection: Choose the appropriate flame retardant grade based on cable density. In dense areas like cable trays or ducts, you should select IEC 60332-3 Category C or B cables.

l Selection Advice for Fire Resistant Cables:

Application Scenarios: Critical circuits that must remain operational during a fire. For example:

Power supply for fire-fighting equipment (fire pumps, fire elevators, smoke exhaust fans).Emergency lighting and evacuation guidance systems.Fire alarm and automatic fire suppression systems.

Key areas requiring uninterrupted communication (such as command centers and data rooms).

Key Principle: Fire resistant cables are "lifesaving cables" used only for systems crucial to the safety of life and property.

Grade Selection: Select cables that meet the specified fire resistance time based on fire safety design codes and fire risk assessments.

Conclusion

Flame retardant and fire resistant cables, with just a single word difference in their names, have vastly different functions. Flame retardant is about fire prevention, slowing down the spread of flames. Fire resistant is about functioning in a fire, ensuring critical systems remain operational. When selecting cables, avoid the temptation of choosing a lower-cost option by using flame retardant where fire resistant is needed, or over-designing and creating unnecessary waste.

Correctly distinguishing and applying these two types of cables is an undeniable responsibility for every project designer and installer. It not only affects a project's economic viability but, more importantly, the safety of lives and property.