Cablofil Steel Wire Cable Tray - Matting Myth Expounded

Cablofil Steel Wire Cable Tray - Matting Myth Expounded

Paul Courson, Managing Director of Cablofil UK explains why the use of matting with high quality steel wire cable tray systems is not only unnecessary but could actually do more harm than good.

National stereotyping is a dangerous business but most Brits would accept our continental peers’ assessment of our character as being somewhat cautious. But, while the UK market tends to want to see proof that a new product type will work well and deliver all the benefits it promises, our market also develops strong loyalties to the products that can demonstrate those proofs – and that’s just what has happened with steel wire cable tray containment. 

When Cablofil first introduced steel wire cable tray to the UK market in 1995, contractors needed to be convinced that it would provide a viable alternative to perforated cable tray. Since then uptake of steel wire systems has grown year on year as more and more contractors realise the speed of installation, ease of use and cost benefits it can offer. Indeed, steel wire cable tray has moved from being a niche product to being the containment system of choice for many contractors – not only for data and small power cabling either, but also for higher voltage cabling and mechanical installations.

With more than 80,000 miles of the Cablofil cable tray has now been installed worldwide and several decades of successful steel wire tray use in all kinds of electrical installations, one might assume that consultants and contractors now trust steel wire cable tray as a flexible, convenient and, above all, reliable form of cable containment. Indeed, most do. There remain some, however, who still don’t trust an open structured system to provide the support required by large quantities of data cables, regardless of the number of installations still successfully performing well after several years service. As a result, they are wasting time, money and effort on installing matting inside the tray: a practice that is not only unnecessary but could actually damage the cables over time.

False assumptions
The problem stems from a single assumption: that the weight of multiple cables on the mesh structure of steel wire cable tray containment will lead to pressure marks on the cables over time at the points where the cables touch the tray. To counter this, the specifiers and/or contractors who buy into this hypothesis deem it necessary to place a flat base, usually a closed cell rubber matting product, inside the basket to protect the cables from pressure marks and the subsequent alteration of the cable technical characteristics. The reality is that a high quality steel wire cable tray will not cause pressure marks on the cables as it has been designed to distribute the weight evenly across the structure and has been proven in situ over periods of 20 years or more to do the job for which it was designed.   

However, the misconception that pressure marks may occur persists and it is now compounded by a misreading of European legislation. European Standards EN 50174-2 (EN 50174-2) were updated in 2009 to help clarify quality requirements and best practice for data cable installations and, for the most part, the updated standards have done just that. However, there is a common belief amongst consultants and contactors that the standards call for the mandatory use of a matting product to avoid the risk of pressure marks when a steel wire cable containment system is used. This is simply not the case. But the misreading of the standards means that contractors are spending money on materials and time on site that are simply wasted.

Hard evidence
For many, the proof of countless installations that have stood the test of time all over the world is proof enough that the addition of matting to a steel wire cable tray installation is surplus to requirements. But, at Cablofil, we don’t expect the market place to take important matters of installation integrity on trust; we prefer to be able to prove it in black and white. That’s why Cablofil commissioned Intertek Testing Services, a division of ETL, the world’s leading provider of testing, inspection and certification services to carry out independent tests using Cablofil steel wire tray.

The aim of the tests was to determine whether there were any advantages to including flatbottomed supports in a steel wire cable tray containment installation for Cat 5e and Cat 6 cables. Two tests were carried out: the first for reliability and the second for durability. For the reliability test, 90 metres of Cat 5e and Cat 6 cables were tested with no load using both Cablofil and a flat surface containment. The cables on both the Cablofil and flat surface were then subjected to mechanical stress equivalent to the weight of 40 data cables stacked together. By measuring and comparing the return loss for each configuration, the test team was able to determine the effect of the support and concluded that there was no significant difference in behaviour between the Cablofil tray and the flatbased support, proving that cables are at no greater risk of pressure marks when Cablofil tray is used alone, without matting. 

For the durability test, the equipment was subjected to a 15 year aging process based on extremely stringent military standards and the same tests were then performed again. The cables and supports were subjected to 200 cycles over large temperature variations (-40°C to +85°C) within a two-week period. The test team’s conclusion was that the natural ventilation from an open containment system like Cablofil actually meant that the cables performed better than they did in the flat-based support system that did not allow heat to dissipate. 

Sound advice
What the test results prove is that the addition of a matting product to a steel wire cable tray installation is not only costly and unnecessary, but that it can also be detrimental to the long-term integrity of the installation. One of steel wire tray’s integral advantages over perforated steel cable tray for data cable installations is its natural ventilation which can help to prevent overheating and matting simply inhibits this ventilation without providing any compensatory benefits. 

While it’s impossible to estimate how much the practice of installing matting with steel wire cable tray is costing the industry, given both the additional costs of buying materials and those incurred by spending extra time on site to lay the matting, it would be fair to say that it’s an overspend contractors can ill afford – particularly in today’s economic climate. 

For the wholesaler, there is a clear role to play in advising contractors about the absence of any real need to use a matting product to avoid pressure marks and to signpost customers to the evidence that supports this view. Naturally, persuading the industry that the practice of using matting with high quality steel wire cable tray systems is unnecessary will not be as simple as that; there is also a long way to go to persuade consultants that the test results outlined above prove that pressure marks are not an issue. However, wholesalers are a vital link in the chain and a trusted source of information for contractors, so if manufacturers and suppliers work together to educate contractors it shouldn’t be too long before installations no longer bow to pressure to include matting in the steel wire tray containment specification.

Press Release : Electrical Wholesaler Magazine April 2010.

Thorne & Derrick UK are Approved Distributors for the Cablofil Steel Wire Cable Basket range of cable containment.

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