Quality of industrial extension leads under investigation

Market surveillance by the Approved Cables Initiative (ACI) has revealed significant quantities of substandard pre-assembled industrial extension leads on sale in the UK.

Pre-assembled yellow units, sold as industrial extension leads designed for use in harsh environments (such as construction sites), have been found marked H05VV-F. These cables are ordinary duty flex and as such are not suitable for industrial use. A sheath of yellow or blue is commonly associated with arctic grade flexibles. 

In one example of such cable, packaging clearly states that the extension lead is designed for use in `harsh environments’ even though the cable is ordinary duty flex (H05VV-F). The cable is yellow and could be easily mistaken for arctic grade flex.

Tests by the Approved Cables Initiative have shown that when the flex is subjected to the cold bend test at minus 40°C, the sheath splits open and insulation cracks exposing what would be live conductors.

Some examples of flex, purchased from a seller on eBay, also failed to meet the tensile strength requirements of an arctic grade and ordinary duty flexible. In one sample the results were more than 30% lower than required.

A further example of an ordinary duty, sold as an industrial extension lead was purchased from a Nationwide Electrical Wholesaler. When subjected to the cold bend test as an arctic grade flex, it failed to maintain its integrity, exposing live conductors. The flex, manufactured in Turkey also failed conductor resistance testing at such a severity that it would warrant a product recall as it poses serious risk of short circuiting and overheating.

In December 2017, the ACI conducted market surveillance aimed at sampling the quality of arctic grade flexibles. Significant quantities of substandard arctic grade flexibles were discovered and the ACI published a warning to the electrical supply chain at this time.

Throughout the course of the ACI’s latest market surveillance programme, various samples have been obtained; a multitude of failures have been recorded across a range of test criteria and requirements. The table below outlines the failures:

Sample purchased from

Sample manufactured by

Failures recorded


Defender Power and Light (owned by Birchwood Price Tools)

Tensile strength of insulation and failure to meet arctic grade cold bend test

Nationwide Electrical Wholesaler

KOC Kablo

Conductor resistance and failure to meet arctic grade cold bend test


Zhe Jiang Shuang Yang

Tensile strength of insulation and thickness of insulation failed


CMK Kablo

Conductor resistance failed


Ebion Kablo

Tensile strength of sheathing failed

Nationwide Multi-Channel Retailer

No manufacturers name

No manufacturers identification on the cable

The ACI is reiterating its message that suppliers and end users who need cable suitable for outdoor use, should look for cable marked BS6004 and the UK cable code for arctic grade cable which is 3183A. Cables marked with H05VV-F are not intended and should not be used in harsh environments.

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