Powerful proof of application suitability
For electrical contractors, the advent of steel wire cable management tray has dramatically reduced data cable installation times, and, as a consequence, helped reduce costs too. Up to 40% quicker to install than traditional perforated steel tray, steel wire tray can be cut, shaped and fixed on site. What’s more, the installer does not need to be a qualified electrician, allowing contractors to free up the time of skilled workers for other tasks and speed up the electrical installation still further.
With all these advantages, it comes as no surprise that this method of cable management has grown dramatically in popularity since Cablofil first introduced it to the UK market 13 years ago. Numerous other companies have launched steel wire tray products into the UK market since then – all of which is great news for the client and the contractor who want to reduce costs by using this cost-effective, time efficient material. Unfortunately, the fact that use of steel wire tray has generally been confined to data cable installations has prevented the industry from reaping these benefits still further. That, however, may now be about to change….
Compiling the evidence
Specifiers look for quality and strength when selecting a cable management solution and steel wire tray can be capable of carrying similar weights to cable ladder, whilst providing a solution that is much lighter and easier to handle.
The problem is that specifiers won’t select steel wire tray instead of cable ladder unless they can be certain that the steel wire product can withstand a short circuit with equal stability. To give them that confidence, we knew we had to prove that Cablofil steel wire tray could withstand short circuit faults, and short circuit testing was the most effective way to deliver that proof.
Having decided to carry out the short circuit tests, Cablofil approached Richard Shaw, the Managing Director of Ellis Patents, to ask whether the company would be interested in helping Cablofil to prove their point.
As independent cleat manufacturers with numerous short circuit tests to their name, we knew Ellis Patents would have the expertise we needed to carry out the tests to the highest standards and with the credibility required to change perceptions. The next step was to meet with the Ellis Patents team and agree the parameters of the tests; the size of cables to be used, the fault current we would test up to and the type of fixing required.
To inform these decisions, Cablofil contacted numerous consultants, contractors and local authority engineers to determine a realistic fault level for most projects.
The point of doing the tests was to gain the confidence of people who work in the industry so that they would be happy to specify Cablofil steel wire tray instead of ladder on real projects. That’s why asking their opinion on this was a critical part of the process.
Cablofil’s research suggested that a peak fault of 70kA would be acceptable for typical commercial, health authority, education facility and domestic projects. However, one customer responded that if Cablofil tray could pass short circuit tests at 100kA they would specify Cablofil instead of ladder for all their power cabling so the test team decided to carry out 100kA fault tests too.
The team from Cablofil and Ellis Patents travelled to the Damstra Laboratory in the Netherlands to conduct the short circuit tests, accessing a specialist facility with a track record in electrical testing dating back to 1936. Part of Eaton Industries, the Damstra laboratory offers Kema and Asta certified test facilities, capable of replicating real short-circuit scenarios.
The tests were prepared using three 35mm single core cables in a trefoil arrangement. The cables were cleated at 600mm intervals and secured to Cablofil CF105/450 tray using a specially developed mounting bracket.
The choice of tray was designed to provide an alternative to the cross section of ladder products that might be used in a typical power cable application. The tray was secured to channel brackets that had been fixed to the test bed at 1500mm intervals and the two lengths of wire tray were connected together using proprietary couplers. Indeed, the whole test platform was installed exactly as we would advise electrical contractors to install both the tray and the brackets so that we could be sure that the tests would offer a genuine indication of how the tray would react in a real short circuit situation.
Once the test was prepared, the three cables were connected to a generator at the head of the test bed and linked by a copper bar at one end to induce the short circuit. The generator was then calibrated before the test began to ensure accurate results.
For the Cablofil tray to achieve a Class 2 pass of the European Standard (EN50368) the cables had to undergo each short circuit test in duplicate. After the first fault was applied only a visual inspection was permitted. The fault was then applied a second time and a pass could only be recorded if the cables and cleats remained secure.
The first tests were carried out using Ellis Patents’ aluminium Alpha cleat and a pass was achieved at 72.6kA. The test rig was then set up again, this time using Ellis Patents’ stainless steel Vulcan+ cleat and once again, the tray achieved a pass, this time at 104kA.
The product was subjected to a great deal of energy during both tests and it performed exceptionally well. The results showed unequivocally that Cablofil steel wire tray can provide a suitable replacement for ladder as a containment for power cables. It’s the result we were confident we would get but it has massive implications for the industry because it provides the proof that specifiers needed to be comfortable with using Cablofil in power cable applications.
While there will always be some projects that demand the use of ladder for power cable containment, the Cablofil short circuit tests have already created a sea change in the way the product is being used. A video of the tests, available to view on YouTube, provides compelling evidence of the ferocity of the tests and has already convinced several engineers that Cablofil tray should be specified more readily for power cable containment. In fact, the specification has already been changed on several projects to reflect the proof of Cablofil as a viable alternative to ladder.
The commercial benefits of using steel wire tray instead of ladder are considerable and these tests pave the way for that to happen. From here on in, the cable management revolution that began with the use of steel wire tray for data cabling applications will also have a profound effect on the way power cables are installed.