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GRP Surface Cable Trough - Cable de-rating

Benjamin Bryden

Hi All,

I'm working on a project where due to existing structures and services we are looking to use recycled plastic cable trough (https://www.hirdtts.com/products/green-trough/200-series/).

Has anyone managed to underpin the de-rating of running cables in this type of surface trough or cable duct, given this is not a standard installation method according to BSEN 60502-2?

Thanks,

Ben

  • 0

    Hi Ben,

    There was an article in Wiring Matters a few years ago covering outdoor surface level troughs which links to some papers by Aners and Slaninka. I believe that these papers are still referenced by cable sizing software but I don't think they've been incorporated into a standard (the software we use directly references the papers still).

    https://electrical.theiet.org/wiring-matters/years/2020/83-november-2020/current-carrying-capacity-of-cables-installed-in-concrete-cable-troughs/

    I would be very interested if there have been any updates though.

    PS - Concrete and plastic troughs are of couse not the same in terms of thermal resistivty of the walls but the method should be similar.

  • 0

    you may well find the bigger problem is estimating the effect of the grouping with the existing services, rather than the detail of containment itself - do you know how close to their own max ratings the existing adjacent service cables already are?
    You are in effect going to reduce their cooling, and need to allow for that, as well as calculating for your own new stuff. Of course if it is all long runs ( say more than > 0.5 m per supply volt) and therefore cables are sized based more on voltage drops rather than thermal limits, it will all run cool anyway and  you are quids in.
    Mike

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