The problem of faulty and potentially unsafe cable in the market is the subject of an ongoing information and awareness programme with stockists, installers and specifiers. Equally important is the accuracy of the information given to describe the performance of the cable. After all it is this information, rather than an analysis of the product, that the purchaser will rely upon to determine if the product is compliant with his requirements.
Unfortunately, in the area of “low smoke halogen free” cables, the lack of agreed terminology to describe the required performance and the reliance on descriptive trade names has already led to the discovery of traditional pvc cables in the market being misrepresented through the product description as “low smoke halogen free” types.
There is now a general agreement on the terminology “low smoke” and “halogen free” which is preferred to the previous use of “zero halogen”. The term “halogen free” may be used to support environmental/ecological needs in meaning the essential absence of halogens in the components of the cable, in a similar manner to the use of terms such as “lead free” or “cadmium free”. However, most often it is used as part of a description of the total fire performance of a cable, in conjunction with “low smoke” to describe a cable giving low emission of smoke and halogen acid gas when burnt.
When used correctly, as in BS product standards (e.g. BS 6724, BS 7211, BS 7629, BS 7846), the terminology is related to defined test methods and defined test requirements:
“low smoke” describes a product tested in accordance with BS EN 61034-2 (the 3 m
cube test) and meeting a minimum requirement of at least 60% for residual light
“halogen free” describes a product tested in accordance with BS EN 50267-2-1 (IEC
754-1) for corrosive and acid gas emission and meeting a maximum requirement for HCl
In some standards, particularly those originating from European Norms, the BS EN 50267-2-2 (IEC60754-2) test, which gives an indirect assessment of corrosivity is used in place of BS EN 50267-2-1.
Whilst reference to British Standards should be used to check claimed performance, problems arise for products for which there is no nationally published standard. In these cases the only description is often through a generic acronym such as LSOH or LSF.
Great care is needed if using such descriptions to define a level of product performance. Many acronyms are in fact trade marks. However, protection of such marks has become increasingly difficult and the major acronyms have become used as generic descriptions. Unfortunately not all users are using them with the same meaning as the trade mark owner and purchasers can thus be mislead into thinking they are buying a “low smoke halogen free” cable as defined by the appropriate tests (as used by the trade mark owner), when they are in fact buying something quite different that has far from low smoke and acid gas emissions.
When buying “low smoke halogen free” cable it is possible to minimise the chances of being caught in the “acronym trap” by following a few simple rules:
Always purchase a recognised brand from a reputable well known manufacturer
Look for compliance with the appropriate BS supported by independent third party
Where no BS product standard exists, look for compliance with the appropriate BS test
standards and requirements described in this paper
Beware of products only described by generic acronyms such as LSF as their
performance may be far from that expected and needed.