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In this blog we are going to discuss about fire resistant and flame retardant cables. Flame retardant cables are designed for using in fire situations where the spread of flames along a cable route needs to be retarded. Fire resistant cables are designed to maintain circuit integrity of vital emergency services during the fire. For flame retardant cables we have two series of catalogues. Fire guard is pvc sheath while firetox is LSZH sheath. Generally flame retardant sheath material is enough, if required grade is high, an extra flame retardant tape would be added. For fire resistant cables we only use LSZH sheath because of its good property. Fire resistant and flame retardant cables are two wide categories. They can involve many kinds of cables such as power and control cables, instrumentation cables, data cables, coaxial cables, fiber optic cables etc.
Let's discuss the different construction between flame retardant and fire resistant cables. First of all we see a flame retardant cable with copper conductor XLPE insulation and LSZH sheath. Now fire resistant cable, the only difference is that there is a mica glass tape between conductor and insulation. Instrumentation cable is to transmit analog or digital signal, so the size of its conductor is small, no larger than 2.5 square millimeter. There are two choices of resisting fire. The first is by adding mica glass tape between conductor and insulation, while the second one is by using silicone rubber as insulation instead of mica glass tape plus XLPE insulation. We can summarize some basic designs for fire resistant cables.
The first one is to use mica glass tape between conductor and insulation, in this case if conductor is too thin to add mica then we can add mica after insulation.
The second one is using silicone rubber as insulation. This design is usually for small conductor size because of the high cost of silicone rubber.
The third one is to add mica glass tape plus silicone rubber. This is double fire resistant design used for high degree resistant requirement.
Caledonian cables can provide special design to meet customers different requirements.
Flame Retardant Standards:
As we know cable is made as per standard for the property of flame retardant and fire resistant, there are also different standard for different grades. Flame retardant tests consists of two modes EN60332-1-2 or IEC60332-1-2 is for vertical single cable test, EN60332-1-2 or IEC60332-3 is for bunched cable test. Undoubtedly non-metallic material such as insulation and sheath is easily get burned. Bunched cables contain more non-metallic material so they are more difficult to pass the test than single cable. The test time dependents on the cable diameter. As you can see from the table of standards, after burning the distance of sharing should be using the data that is stipulated in this standard. You can learn more through reading the standard content. For bunched cable tests, there are three categories with different quantity of non-metallic material and different time. Through the table we can see category 8 which is EN60332-3 or IEC 60332-3-22 is the highest level for flame retardant test.
Fire Resistant Test Standards:
Now we come to fire resistant test standards. As we told in the beginning, circuit integrity is the essential point for fire resistant cables. Therefore, if the cable can still work as normal after test it is considered to pass test. Tests always consists of fire test, water spray test and mechanical shop test. It varies according to the standards. Here I summarize popular standards for testing circuit integrity with test items and time. The following page a brief introduction for each standard. Now let's discuss the first standard IEC60331-21. Lets take a cable sample of 1.2 meter in length and place it on a gas burner and connect to an electrical supply at its rated voltage. Fire is applied for a period of 90 minutes. Later the cable sample is re-energized and must maintain its circuit integrity this is an ordinary test for fire resistant. Then we talk about more strictest standard called BS6387CWZ, it consists of three parts of tests which are fire, water and mechanical shock. So we will hear BS6387CWZ frequently in the future because it is almost the strictest test for fire resistance.
Certifications:
The most assertive certification for fire resistant cables is LPCB. Now we are applying for it, we already have many test reports for fire resistant cables. We can provide test report with the nearest construction as required by our customers. I want to draw your attention to the difference between certification and test report. They all are issued by third party. Test report is to test a designated quantity of sample, which shows concrete conductor size. For example BS8573 copper conductor XLPE insulation and LSZH sheath 3cx1.5. Certification is for a series of kind of cable and also need factory inspection. For example BS8573 copper conductor XLPE insulation LSZH sheath, all single core and multi-core cables.
Application of Fire Resistant and Flame Retardant Cables
Fire-resistant and flame-retardant cables are designed to prevent or delay the spread of fire and limit the propagation of flames and smoke in the event of a fire. These specialized cables are commonly used in various applications where fire safety is crucial. Here are some key applications of fire-resistant and flame-retardant cables:
Buildings and Infrastructure: Fire-resistant and flame-retardant cables are extensively used in commercial buildings, residential complexes, hospitals, schools, and other structures where fire safety is a priority. These cables are typically employed for power distribution, lighting, communication systems, and other electrical installations. They help maintain critical electrical functions during a fire and prevent the spread of fire through the cable network.
Transportation Systems: Fire-resistant and flame-retardant cables play a critical role in transportation systems, including railways, airports, and tunnels. These cables are used in signaling and communication systems, power distribution, lighting, and other electrical installations. They provide vital electrical connectivity in emergency situations and contribute to passenger safety by minimizing the risk of fire propagation.
Oil and Gas Industry: In the oil and gas industry, fire-resistant and flame-retardant cables are used in offshore platforms, refineries, petrochemical plants, and other hazardous environments. These cables are engineered to withstand high temperatures, chemical exposure, and mechanical stresses. They ensure reliable power supply and control in critical equipment and reduce the risk of fire accidents in these high-risk settings.
Data Centers and IT Facilities: Fire-resistant and flame-retardant cables are essential in data centers, server rooms, and IT facilities where sensitive electronic equipment and valuable data are housed. These cables help maintain the integrity of power and data transmission during a fire event. By minimizing fire propagation and smoke generation, they contribute to the overall fire safety of these facilities.
Industrial and Manufacturing Facilities: Fire-resistant and flame-retardant cables are widely used in industrial and manufacturing settings. These cables are employed in power distribution, motor control, machinery, and equipment wiring. They help protect critical processes, machinery, and personnel by minimizing the impact of fire incidents and ensuring continuous operation during emergencies.
Hazardous Environments: Fire-resistant and flame-retardant cables find applications in hazardous environments such as chemical plants, pharmaceutical facilities, and power generation plants. These cables are designed to resist the effects of fire, chemicals, and extreme temperatures. They provide reliable electrical connectivity in areas where the risk of fire and explosion is significant.
Fire-resistant and flame-retardant cables are an important component of fire safety systems in various industries and settings. They are designed to mitigate the spread of fire and ensure the continuity of critical operations during emergencies, contributing to the protection of life, property, and infrastructure.
