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Construction Products Regulations - What Cable Manufacturers Need to Know.

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The European Union (EU)’s Construction Products Regulation (CPR) (1) is far-reaching legislation that covers many aspects of all kinds of building materials sold into the European Economic Area (EAA).

The CPR aims to remove technical barriers to trade in the EU and to ensure reliability of material performance information using standards and uniform test methods (2). Manufacturers, distributors, and importers of construction products going into the EAA are responsible for ensuring their products meet the requirements.

Although there was much debate regarding test methods and performance requirements for cables, these issues have now been resolved and requirements for cables under the CPR came into effect as of 1 July 2016, with a transition period until 1 July 2017, when the requirements become mandatory. At that time, all cables marketed in the EAA must comply with new testing, certification, and CE marking requirements as spelled out in the European product standard EN 50575 (3).

Cable requirements under the CPR

Cables will be categorized under the Euro classifications A to F, which define reaction to fire based on the following test methods (3, 4).

·       EN ISO 1716 measures gross heat of combustion or calorific potential (PCS).

·       EN 50399 measures heat release rate (HRR), total heat release (THR), peak heat release, fire index growth rate (FIGRA), flame spread (FS) and smoke production measurement on cables during a test with either a 20.5 kW or a 30 KW flame source.

·       EN 60332-1-2 is a single vertical fire test that measures the height (H) of the combusted length of cable after a flame (1 KW) is applied.

·       EN 61034-2 measures smoke density of cables burning under defined conditions.

·       EN 50267 measures acidity of gases after cables are completely consumed.

These test methods measure criteria considered key to predicting how a cable will behave in the event of a fire, which include:

·       Ease of ignition of the cable

·       Speed and distance the fire would propagate along the cable

·       Quantity of smoke generated by the burning cable

·       Toxicity of the by-products of the cable combustion

·       Corrosivity of the by-products of the cable combustion.

Class A has no contribution to a fire, Classes B through E have some contribution to a fire measured by these tests (details shown in Table I), and Class F has no requirement.

Under the CPR, all cables marketed in the EAA must carry a CE mark for one of these categories, which indicates that the product has met the test requirements. Each EU country’s governing body can decide what classification requirement is needed for cables going into new construction; these are expected to include B2, C, and D.

Table1

What aspects of a cable affect fire performance test measurements?

Some of the factors that affect a cable’s fire performance include:

·       conductor type and cross-sectional area

·       insulation type and thickness

·       the number of insulated cores in the cable

·       the lay angle of the cores

·       Presence or absence of binding tapes and tape type

·       Presence or absence of a bedding or filling layer

·       Bedding or filling material type and thickness

·       Extrusion technique used to apply the bedding or filling layer

·       Presence or absence of metallic armouring or braid

·       Armouring type, coverage, and lay angle

·       Sheathing compound type and thickness

·       Extrusion technique used to apply the sheath.

Sometimes the design and construction of the cable are fixed, and the sheathing compound is the main constituent that can be changed.

Cable materials for the CPR

Low-smoke, zero-halogen (LS0H) compounds—also called LSHZ, LSHF, HFFR or HFFR-LS (halogen-free flame retardant-low smoke) are designed to reduce the propagation of fire and have low smoke emissions. 

In addition, being free of any halogen-containing materials (including PVC or halogen-containing flame retardants), they have reduced evolution of toxic gases which, coupled with the reduced smoke evolved, allows increased time for personnel to leave a building before becoming disorientated and incapacitated during a fire.

These types of compounds are in widespread use throughout Europe, but it is expected that increased use will be seen as a result of the CPR coming into operation. 

For typical dwellings and buildings, cables with class D or C rating appear to be those specified by individual countries within Europe; for high occupancy or buildings which are difficult to evacuate, such as hospitals, class C or B2 are being stipulated.  The choice of compound will depend on which class is specified and whether there are additional requirements, such as no dropping particles.

Cable makers that are affected by the CPR are in the process of acertaining what class in the CPR their current cable designs are capable of meeting. 

Where the cables are not able to meet the required level, designs may have to be changed, which may involve the use of alternative materials for the various components of the cable. 

The choice of these materials is a difficult task, since it is not easy to correlate small-scale tests made on individual materials to how the complete cable will burn in the EN50399 vertical burn test.  In addition, minor changes to the physical design and size of the cable can have a big impact on the class that the cable ultimately achieves

Since there is no hard data that can easily be applied to how a cable will perform made with certain materials, it then becomes a matter of experience of which grades to recommend. A compound supplier has valuable insight into the behaviour of materials during combustion, which enables them to make informed recommendations on the choice of materials to meet the required classifications in the full-scale test.

For more information: 

Mexichem’s technical support team is on hand, not only recommend suitable materials, but also to attend extrusion trials to ensure that the compounds are processed in such a way as to give the best performance on the cable.  Being also able to witness the fire tests will also assist the team in tailoring the compound to customers’ particular designs and requirements, thus providing full support and turnkey solutions.

 

References

1. EC, “Construction Products Regulation,

2. Gov.UK, “EU Construction Products Regulation and CE marking, including UK product contact point for construction products,” 

3.    EN50575, “Power, control and communication cables – Cables for general applications in construction works subject to reaction to fire requirements" 

4. SP Technical Research Institute of Sweden, “Cable fire testing and research”