|
Click on the cover to read the latest issue of PSB
Affiliate Links
|
Cable management: cleats count24 August 2011Cable cleat manufacturer Ellis Patents has been at the forefront of the industry’s efforts to establish proper installation procedures for this critical area of cable management. Managing director, Richard Shaw warns of the dangers of poor installation practiceCable cleat manufacturer, Ellis Patents has been vocal in its attempts to draw attention to the importance of properly installed cable cleats in electrical installations. And although significant progress has been made, there is still a long way to go, as managing director, Richard Shaw, explains:
“The problem we’ve faced trying to get our message across has been twofold. Firstly, there are deeply ingrained installation short cuts that have happened so frequently and for so long that a lot of installers aren’t even aware they’re taking them. And secondly, because different cleat manufacturers don’t all work from the same hymn sheet, the market is very much a mish-mash of products of differing quality.”
Taking the installation issue first, the company has focused a lot of attention on the task of eradicating these short cuts. Its approach has been to educate the market as to the dangers posed by a practice that has arisen largely because the importance of cleats is underestimated. This has led to them simply being ‘lumped in’ with the electrical sundries and seen as fair game for cost-cutting when installers seek to keep within tight budgets.
The inherent danger of this practice is that it poses a risk to life; an under-specified cleat offers as much short circuit protection as a plastic cable tie – that is, precisely none. In fact, the only thing under-specified cleats would do in a short circuit situation is add to the shrapnel.
This message, and the hard hitting imagery it provokes, has proved extremely effective, and when you add in the publication of European (EN50368) and International (IEC61914) standards, it’s fair to say great strides have been taken in changing people’s attitudes towards cleats.
However, the journey is far from over. The standards are only advisory, which means those claiming adherence to them can do so through self-certification. And this is where the problems, as far as the manufacturers are concerned, begin.
Today, it is not uncommon for manufacturers to claim a given short circuit withstand at a given cleat spacing and legitimately provide third party certification to support this. However, the overlooked fact is that the quoted short circuit withstand is only valid for a cable diameter equal to, or greater than, the diameter of the cable used in the test. If the project in question is using smaller cables than those referred to in the test (and the fault level and spacing is the same) then the force between the cables is proportionally greater and the certificate is inappropriate.
So, the question is how to resolve a potentially fatal issue that is being inflamed by bad practice and the misunderstanding of all parties, from the manufacturers and specifiers, to the contractors and installers?
Of course, the situation could be resolved through a process of education and agreement involving all these parties and industry regulators, but this would be a long-term process that fails to take into account the dire need for a quick-fix before the unnecessary threat to life caused by the problem turns into the wholly unnecessary loss of life.
There is only one sensible and safe solution: cable cleats need to start being treated as circuit protection devices – meaning they are given the same degree of importance as a fuse or a circuit breaker. After all, in the event of a fault, the forces between cables reach their peak in the first quarter cycle and this is the point that cleats earn their crust. In contrast, circuit breakers typically interrupt the fault after 3 or even 5 cycles by which time, if the cleats are under-specified, the cables will be long gone!
Wider adoption of this attitude would ensure the correct use and installation of cleats. And when you consider what this means in terms of delivering safer electrical installation, it’s fair to say that such an approach is absolutely the right course of action.
Contact Details and Archive...Related Articles...Most Viewed Articles... |
|