Sub-Standard Cables — Contractors Beware

Unfortunately, with the globalisation of the manufacturers and the harmonisation of the core colours within Cenelec the problem has returned. While the cable may look perfect, generally this is furthest from the truth. Copper and PVC are global commodities and as such are internationally traded. Therefore the costs of high grade copper and premium grade PVC are subject to market fluctuations.

If cables are being sold at knockdown prices, it may seem a bargain to the contractor giving them increased profit margins in the short term. In the long term, it is likely they will have headaches as the installations consistently break down.

The golden rule is look for an approvals mark. This mark is normally embossed on the insulation of non-sheathed single core cables and on the outer sheath on flexible cables that are fully harmonised within the EU, an example is plus the manufacturers name or trademark. This marking ensures the cables are subjected to third party testing. VDE is the German National Accredited Body that runs the HAR scheme within Germany. Most countries have their own unique accredited bodies and are registered within the Cenelec system under the HAR Agreement. The HAR Agreement entails the random selection and testing (to the required cable standard) of finished cable from the manufacturing plant, where up to 150 samples are selected and tested per annum, ensuring that highquality is maintained.

The graphical symbols of the common HAR mark from each country is as follows:-

Austria  OVE  HAR
Belgium  CEBEC  HAR
Czech Republic  EZU  HAR
Denmark  DEMKO  HAR
Finland  FIMKO  HAR
France   USE  HAR
Germany  VDE  HAR
Great Britain  BASEC  HAR
Greece   ELOT  HAR
Hungary  MEEI  HAR
Ireland  NSAI  HAR
Italy   IEMMEQU HAR
The Netherlands KEMA-KEUR HAR
Norway   NEMKO  HAR
Portugal  CERTIF  HAR
Spain   AENOR  HAR
Sweden   SEMKO  HAR
Switzerland  SEV  HAR
Turkey  TSE HAR

A similar scheme is in place for “House Wiring Twin and Earth Cables”. The only difference is the HAR mark does not appear, only the manufacturers name and the approvals body eg BASEC.

In relation to non-approved cable, this is where the manufacturers are using the CE marking directive. They are marking the cable with their name plus the letters CE, this is giving the impression that the cables have third party approval.

The main problems with unapproved cable is as follows:
— Low grade copper giving a high conductor resistance;
— Poor quality PVC ie polymer that has excessive amounts of filler and low grade plasticizer resulting in poor insulating properties;
— Thin insulation and sheath.

With the combination of the above, the life span of the cable operating at the designed temperature is reduced significantly.
The normal life span of a high-quality cable is in the region of 25 years, however, with the unapproved cable this can be as little as 5 to 7 years.
In conclusion, contractors should be extremely careful in the selection of cables they are purchasing ensuring the appropriate approval marks are visible on the cables.