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Changing legislation affecting cable joints

Author : Jonathan Rawlinson, technical manager at Prysmian Cables & Systems

You may or may not have already noticed that labels on certain cable jointing products have changed and now carry the worrying phrase, “suspected of causing cancer” with a logo to match. You also may or may not know why this has happened and what it means for your day job.

Changing legislation effecting cable joints

If you work with electrical cables, whether as a contractor or distributor, then undoubtedly you will have to join them together at some point using a resin joint or sell products enabling this. So, it is important to understand the reasons why this new labelling has come into force and what the implications are to your health when using products with these new warnings.

What is happening?

In a nutshell, conventional technology associated with most cable jointing resins uses polyurethane. A major chemical ingredient in this material is an isocyanate known as MDI. There have been concerns for some time that this chemical ingredient presents a real health and safety risk to those who work with products containing it. Consequently, multiple attempts have been made at a European level over the past 10 years to have MDI re-classified as a carcinogen (a substance that is an agent directly involved in causing cancer).
The EU via the European Chemical Agency (ECHA) has the responsibility of doing this and also implementing a new globally harmonized labelling system (CLP). Under the new system MDI is now classified as Carcinogen Category 2 – “Suspected of causing Cancer”.

From December 1st 2010 any cable joint resin product containing MDI has new labelling. This labelling carries the new “cancer” warning and also warns of other risks associated with MDI already well known. These include being an irritant to skin and eyes as well as being a sensitizer (a chemical which may lead to the development of allergic reactions after repeated exposure).

What has been done about this?

Companies such as Prysmian have been working on resin solutions that present no health and safety risk for some time. As far back as 1998, a major UK power utility approached Prysmian with concerns that resin joint kits containing MDI could have adverse affects on staff.
The idea was to create a non-hazardous MDI free system for jointing of electrical cables that also complied with the requirements of the European standard BS EN 50393 and the Energy Networks Association Engineering Recommendation C81 type test.

Some have suggested that HDI is a suitable alternative to MDI, as it is not affected by the changes to legislation. However, there are disadvantages associated with this chemical.
Firstly, the raw material cost of HDI is substantially higher than that of MDI. This would result in a prohibitively high cost for the resulting resin. Also, HDI based resins have little service history in buried cable jointing applications and are known sensitisers.

Perhaps of even more importance with this chemical is that it could be re-classified in future in much the same way MDI has been. So, using HDI based resins now could result in the same issues currently being faced by those containing MDI.

In1999 Prysmian successfully developed the new JEM (Joint Encapsulation Material). Independent extensive testing to International Standards subsequently proved the product to be non-irritating to eyes or skin and non-sensitising. This means JEM resin kits have to carry none of the hazard labelling currently required by those containing MDI. JEM resins are also non-flammable and therefore do not require any special storage or transport. During development JEM resin underwent large scale filed trials proving that the product performs as intended.


It is important to say that there is no requirement for change in existing working practice when handling resins containing MDI; current levels of industrial hygiene and PPE should be maintained.

This is because the listing of MDI as a Carcinogen category 2 was the result of testing with it in aerosol form. With cable jointing resins coming in liquid form, it is true that the risk of cancer occurring cannot be truly quantified, even if the material is swallowed or vapours inhaled.

Nonetheless, that is not to say the material cannot cause irritation and allergic reactions that then become permanent. The most common result of inhaling MDI vapour is still respiratory sensitisation leading to occupational asthma.

It would be prudent to make sure that any risk of this happening to your staff, customers or yourself, no matter how small, is eliminated. One way of doing this is to use jointing resins such as JEM. Since December 1st 2010, all Prysmian resin jointing kits are JEM only and contain no harmful MDI. JEM also has a proven track record in the field, with more than 4 million litres already installed with zero electrical failures and a host of technical and environmental benefits.

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