Cable Fire Resistant Test EN 50200, IEC 60331, BS 6387

What is the Fire Resistant Cable?

The Fire Resistant Cable can work properly for a certain period of time when subject to a fire. The specified fire conditions normally are a propane gas flame at a temperature of 650 to 950 degrees, with/without mechanical shock, or spray water.  

The structure of fire resistant cables is similar to ordinary cable, what the differences are:

1)      Adopts copper conductor to achieve higher melting point;

2)      Increase a fire resistant layer between the conductor and the insulation layer. The fire resistant layer is typically a multi-layer of mica material tape.

The structure ensures the fire resistant cable work properly for a certain time in the event of a fire. This characteristic determines fire resistant cable can be used in critical electrical circuits, such as power supply circuits for emergency power of fire-fighting equipment, fire alarm equipment, ventilation and smoke exhaust equipment, emergency indicator lights, and emergency elevators.

Fire Resistant Cable vs Flame Retardant Cable

In parallel to fire resistant cables, flame retardant cables are another significant category.

The flame retardant cable will not propagate or convey a flame when subject to a fire, and after the external fire source is extinguished, the cable can be self-extinguished, or flame spread within a limited distance.

The structure of flame retardant cables is basically the same as the ordinary cable, the difference is all or parts of the cable’s insulation layer, sheath layer, and auxiliary parts are made of flame retardant materials. Using flame retardant materials makes the cable less flammable, limits flame spread and better self-extinguish capacity when exposed to a fire.

Fire resistance cable and flame retardant cable improve the safety of cable when subject to a fire. While fire resistance cables are generally used in critical circuits to ensure the circuit integrity for critical functions to continue at a specific time in the event of a fire. And the flame retardant cables are used wider since it doesn’t promote the spread of fire.

For more information on the flame retardant cable fire tests and classification, refer to “European Cable Fire Testing and Classification”.

Fire Resistant Test Standards for Cable

EN 50200

Method of test for resistance to fire of unprotected small cables for use in emergency circuits

IEC 60331 Series

IEC 60331-1 — Test method for fire with shock at a temperature of at least 830 °C for cables of rated voltage up to and including 0.6/1.0 kV and with an overall diameter exceeding 20 mm

IEC 60331-2 — Test method for fire with shock at a temperature of at least 830 °C for cables of rated voltage up to and including 0.6/1.0 kV and with an overall diameter not exceeding 20 mm

IEC 60331-3 — Test method for fire with shock at a temperature of at least 830 °C for cables of rated voltage up to and including 0.6/1.0 kV tested in a metal enclosure

IEC 60331-21 — Procedures and requirements – Cables of rated voltage up to and including 0.6/1.0 kV

IEC 60331-23 — Procedures and requirements – Electric data cables

IEC 60331-25 — Procedures and requirements – Optical fibre cables

BS 6387

Test method for resistance to fire of cables required to maintain circuit integrity under fire conditions

BS 8434 Series

BS 8434-1 Methods of test for assessment of the fire integrity of electric cables - Part 1: Test for unprotected small cables for use in emergency circuits - BS EN 50200 with addition of water spray

BS 8434-2 Methods of test for assessment of the fire integrity of electric cables - Part 2: Test for unprotected small cables for use in emergency circuits - BS EN 50200 with a 930 degree C flame and with water spray

BS 8491

Method for assessment of fire integrity of large diameter power cables for use as components for smoke and heat control systems and certain other active fire safety systems

DIN 4102-12

Fire behaviour of building materials and elements - Fire resistance of electric cable systems required to maintain circuit integrity - Requirements and testing

SS 299:2021

Fire-resistant cables of rated voltage up to and including 600/1000 V for fixed installations, having low emission of smoke and corrosive gases when affected by fire – Requirements and test methods

Fire Resistant Test Methods

The principles are the same between the different test standards, but the following variations exist.

• Burner type.

• Flame temperature.

• Additional external shock.

• Flame application time

The test method comparison of EN 50200, IEC 60331, and BS 6387.

Cable Fire Resistant Test Apparatus

Considering the diversity of fire resistance tests, a fire resistance test facility that meets all test criteria should contain the following features：

Electrical Control Rack

• Independent control rack, ensuring control safety and reliability.

• Provides transformer voltage adjustable, can adapt to the different product working voltage, and when the test current leakage, can provide sufficient test voltage.

• Provides 5 test channels, transformer voltage in series with fuse, and circuit breaker for protection of each test circuit.

• Operation software with test control, data recording, data processing, report output, etc.

Source of Heat

• The heat source consists of a pressure-reducing valve, pressure gauge, mass flow meter, venturi mixer, and burner.

• The gas pressure reducing valve provides a stable 0.1Mpa ± 3Pa outlet pressure.

• The pressure gauge provides a pressure display up to 200 kPa.

• The mass flow meter provides a consistent propane gas supply with an accuracy of ±2%.

• 500mm Ribbon type gas burner, supplies a propane flame of 650 °C ± 40 °C, 750 °C ± 50 °C or 950 °C ± 40 °C.

• 610mm Tube type gas burner, supplies a propane flame of 950 °C ± 40 °C.

• Flame temperature calibration device, using K-type stainless steel insulated thermocouple, the calibration results are displayed directly on the software.

• The flame application time can be set according to different standards and automatically cut off.

Resistance to Fire Alone Test Bench

• Comforts to BS 6387 Protocol C.

• Independent test bench, the cable sample can be held horizontally on the support rings.

• Burner carriage, which can install the ribbon-type gas burner and tube-type burner. The burner can be fine adjusted the height to suit different kinds of cable samples.

• The cable sample support frame, metal ring, and support frame are well-grounded.

Resistance to Fire with Water Test Bench

• Comforts to BS 6387 Protocol W.

• Independent test bench, the cable sample can be attached to metal support and held in a test frame.

• Burner carriage, which can install ribbon-type gas burner. The burner can be fine adjusted the height to suit different kinds of cable samples.

• The Sprinker water spray device, positioned centrally with respect to the burner, supplies constant sprayed water to the cable sample between 0.25 and 0.30 L/m2/s.

• Stainless steel water tank, collect the spray water and burning debris.

• The cable sample metal support, test frame, and test tank are well-grounded.

Resistance to Fire with Mechanical Shock Test Bench

• Comforts to EN 50200 and BS 6387 Protocol Z.

• Independent test bench, the cable sample can be mounted on the vertical non-combustible board.

• Burner carriage, which can install ribbon-type gas burner. The burner can be fine adjusted the height to suit different kinds of cable samples.

• The cable sample mounting rig is well-grounded.

• Shock producing device, produces mechanical shock with a φ25mm by 600mm long steel bar in the interval of 30s.

• (additional) Tube water spray device according to EN 50200 Annex E.

Contact us for more information on Fire Resistant Test Apparatus or refer to “Cable Fire Resistant Test Apparatus”.

Summary