EN 50575 European Cable Fire Testing and Classification
What is Construction Products Regulation (CPR) for Cables?
The Construction Productions Regulation (CPR) is the building materials directive of the European CE marking.
CPR covers all building products, including cables, classified by its reaction to fire behavior.
The EU published Regulation 2016/364 in March 2016, which sets out fire ratings and corresponding test methods for all types of construction materials, including electrical cables. Also according to European Commission Notice 2015/C 378/03, EN 50575 has officially become the standard for reaction to fire requirements for wire and cable for construction in July 2016 and the standard will be officially implemented from 1 July 2017.
Any cable products already on the market prior to this date can continue to be sold and supplied without reference to the CPR. The cable products manufactured and sold after this date will need to comply with the standard EN 50575, which classifies wire and cable fire ratings according to their behavior of heat of combustion, heat release & smoke production, vertical flame propagation, smoke density and acidity & acid gas content. The CPR ranking highest to lowest are: Aca; B1ca; B2ca; Cca; Dca; Eca and Fca.
CPR is mandatory for all European countries, but the minimum CPR requirements may vary from country to country. Some countries have implemented a minimum classification and some countries have adopted a risk assessment methodology based on the type of installation or its fire suppression system.
The cable products covered by CPR regulations contain the following.
Power cables – insulated conductors and cables for use in, e.g. the supply of electricity;
Control and communication cables – wires, symmetric cables, and coaxial cables with metallic conductors for use in, e.g. telecommunication, data transmission, radio frequency, video communication and signalling and control equipment;
Optical fibre cables – for use in, e.g. telecommunication, data transmission, radio frequency, video communication and signalling and control equipment.
Test method/standards involved in CPR:
| EN ISO 1716 | Reaction to fire tests for products — Determination of the gross heat of combustion (calorific value) |
| EN 60332-1-2 | Tests on electric and optical fibre cables under fire conditions — Part 1-2: Test for vertical flame propagation for a single insulated wire or cable — Procedure for 1 kW pre-mixed flame |
| EN 50399 | Common test methods for cables under fire conditions — Heat release and smoke production measurement on cables during flame spread test — Test apparatus, procedures, results |
| EN 61034-2 | Measurement of smoke density of cables burning under defined conditions — Part 2: Test procedure and requirements |
| EN 60754-2 | Test on gases evolved during combustion of materials from cables — Part 2: Determination of acidity (by pH measurement) and conductivity. |
Classification, Test method and AVCP Systems
| Class | EN ISO 1716 | EN 60332-1-2 | EN 50399 | EN 61034-2 | EN 60754-2 | AVCP |
|---|---|---|---|---|---|---|
| Aca | R | - | - | - | - | 1+ |
| B1ca | - | R | R | ○ | ○ | 1+ |
| B2ca | - | R | R | ○ | ○ | 1+ |
| Cca | - | R | R | ○ | ○ | 1+ |
| Dca | - | R | R | ○ | ○ | 3 |
| Eca | - | R | - | ○ | ○ | 3 |
| Fca | - | R** | - | - | - | 4 |
R - Required.
○ - Optional, addtional for subclasses.
** - May be carried out by manufacturer
The fire performance of cables is classified based on a number of test:
Flame spread (EN 60332-1-2, EN 50399).
Heat release (EN ISO 1716, EN 50399).
Flaming droplets (EN 50399).
Smoke release (EN 61034-2).
Acidity (EN 60754).
Classification of fire performance
7 Classifications for flame spread and heat release: A, B1, B2, C, D, E and F (A is non-combustible and F is no criteria specified).
5 classifications for smoke release: s1, s1a, s1b, s2, s3 (s1a is the most smoke-free and s3 is no criteria specified).
3 classifications for flaming droplets: d0, d1, d2 (d0 is the most droplet-free and d2 is no criteria specified).
3 classifications for acidity: a1, a2, a3 (a1 is the most acidity-free and a3 is no criteria specified.)
A specimen in specified mass is burned under standardized conditions, at constant volume, in an atmosphere of oxygen, in a bomb calorimeter calibrated by combustion of certified benzoic acid. The heat of combustion determined under these conditions is calculated on the basis of the observed temperature rise, taking account of heat loss and the latent heat of vaporization of water.
Test Procedure of the Bomb Calorimeter Test
a) Prepare 3 sets of test specimens (sampling & conditioning)
b) Weight a specimen and place it in the crucible.
c) Place the crucible in the holder, attach the firing wire and loop it to touch the specimen (1ml de-ionized water is added to the calorimetric bomb to absorb the combustion gases).
d) Place the holder in the calorimetric bomb, and tighten the lid.
e) Fill the oxygen into the calorimetric bomb until a pressure of 3.0 to 3.5 MPa is achieved.
f) Insert the bomb in the calorimetric vessel.
g) Introduce the calorimeter system into ready condition.
h) Start the test with the auto program of the calorimeter system.
i) Check the test result.
j) Remove the bomb from the calorimeter vessel.
k) Cooling down and slowly reducing the pressure. Open the bomb and clean the combustion residues.
l) Test all three specimens with the same procedure.
Key Test Results:
Gross heat of combustion, in MJ/kg.
Flame Propagation Test
A cable specimen is mounted vertically and exposed to a 1 kw pre-mixd flame for 60/120/240/480 seconds, record the afterflame time and burning behaviour of the cable after removal of the flame, and measure the flame propagation distance of the cable.
Test Procedure of the EN 60332-1 Test
a) A piece of single insulated cable with a length of 600mm, is mounted vertically.
b) Stabilize the ignition source as per IEC 60695-11-2, and adjust the burner angle to 45 degrees.
c) Impinge the flame to the insulated cable, at a distance of 475mm.
d) Observe and remove the flame after the specific flame application time.
e) Repeat two more tests.
f) Evaluate the test results.
Key Test Results:
Flame spread distance, in mm.
EN 50399 Test
Bunched cables are mounted on the ladder, the ladder is installed vertically inside the test chamber, and the cable is exposed to a 20.5 or 30kw burner flame for a test time of 20 minutes.
During the EN50399 test, the combustion gas generated is collected and sampled for analysis, and the heat release rate and smoke production rate are calculated. At the same time, the flame spread and burning droplets are recorded, and fire damaged length of the cable is measured when the test is finished.
Test Procedure of the EN 50399 Test
a) Prepare test specimens (conditioning).
b) Supply the air to the test chamber at the rate of 8000L/min.
c) Adjust the exhaust duct rate to 1.0 m3/s.
d) Stabilize the analysis system (Analyzer, smoke measuring, sampling device, DAQ…)
e) Mount the cables to the ladder, and install the ladder to the test chamber vertically.
f) Install the burner carriage to the position and close the test chamber.
g) Run the MOTIS EN 50399 Test Program.
h) The software would run the standard program automatically, including baseline running, burner flame application, data acquisition, continuous analysis, continuous calculation, and test result output.
i) Records the flame spread condition and droplets during the test.
j) Measure the fire damaged length of the cable when the test is finished.
Key Test Results:
Heat release rate, HRR, in kW.
Total heat release, THR, in MJ.
Smoke production rate, SPR, in m2/s.
Total smoke production, RSP, in m2.
Fire growth rate index, FIGRA.
Flame spread, in mm.
Fire damage length, in mm.
Occurrence or not of flaming droplets.
Smoke Density Test
The cable is mounted on a tray horizontally, inside a corner of a cubic test chamber with an internal dimension of 3000mm x 3000mm x 3000mm. The cable is exposed to a standard fire source beneath, and the generated smoke fills the chamber, and the system detects its density by the photometric system installed on the chamber wall.
Test Procedure of the EN 61034 Test
a) Prepare 6 sets of test specimens, three lengthwise and three crosswise (conditioning).
b) Check the required airflow velocity (0.7 m/s) in the chimney of the combustion chamber.
c) Install the specimen to the specimen holder and mount the holder into the test chamber.
d) Light the burner and adjust the flame height to 20mm in the vertical direction.
e) Tilt the burner to 45 degrees.
f) Impingement of the flame to the specimen (surface or edge exposure) 15 seconds.
g) Remove the flame after 15 seconds, and record the flaming time, flame spread height, and droplets during the test.
h) Test all six sets of specimens with the same procedure.
Key Test Results:
Ignition time, in second.
Whether the flame tip reaches 150mm above the flame application point or not.
Presence of droplets/particles
Corrosion Test Apparatus
1 Gram specimen is put on the combustion boat, the boat is fed into the tube furnace, the specimen is completely lysed at 800 or 900 degrees, and a stream of dry air is supplied to take the released combustion gas out, the gases are absorbed in wash bottles. The halogen acid content is determined by titration. The pH value and conductivity are determined by a pH meter and conductivity meter.
Test Procedure of the EN 60754 Test
a) Prepare the test specimens, each specimen shall be taken from a sample representative of the cable.
b) Heating up the furnace tube to 800/900 degrees.
c) Prepare the wash bottle with the agent dissolved.
d) Weight 1 gram specimen to the combustion boat, and feed the boat into the furnace tube.
e) Supply the dry air into the furnace tube.
f) Remove the combustion boat, and take the absorbed solution from the wash bottle for the halogen acid content test, Acidity test (pH), and conductivity test.
Key Test Results:
Halogen acid content.
pH value.
Conductivity.
Summary
The European Construction Regulations (CPR) uniformly regulate the fire performance of electric cables.
It provides unified requirements for power, control, communications, and optical fiber cables intended for installations in all types of construction used in all EU member countries.
MOTIS offers all CPR Cable Test (EN 50575) instruments and provides technical support services for laboratory establishment, contact us for more information.