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Cables in heating voids

Martyn
Hi Folks,


'intresting' day today...


So at the moment I am replacing a 150kW gas warm air unit, a huge thing in a commercial building.


Today I finished ripping out the old unit (146kW) the system draws in fresh air from outside and distributes the warm air via a network of underground ducts, really they are just concrete tunnels large enough to crawl through.


So being inquisitive and not being able to resist this unknown hole to somewhere in the floor of the plant room I stuck my ladders down there and went for a wander (pig in sh*it comes to mind ?) as soon as I get in there are 4 25mm galve conduits (building lighting 10x 10A) and a 25 2c SWA (feeding a kitchen sub 100A) with a 10mm earth attached snaking through there, I wander further 25m ish still the armoured and conduits but also a few fire alarm cables have entered the scene.


Swa -90's

Conduits - either 73 or 90's


Clearly a very convienient route for cables and none of them are showing any outward signs of distress (cant see in the galv conduits ofcourse)


Thoughts? Just canvasing opinion...
Parents
  • 0
    Cables need then to be de-rated rather as of they were grouped with some other cable running hot. How much to derate much requires some understanding of the system, or probably more usefully some of those peak temperature stickers.

    Moving hot air is less of an issue, as it is not there long enough to get much hotter, More of a problem would be places that heat up but d not have much draught.
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  • 0
    Cables need then to be de-rated rather as of they were grouped with some other cable running hot. How much to derate much requires some understanding of the system, or probably more usefully some of those peak temperature stickers.

    Moving hot air is less of an issue, as it is not there long enough to get much hotter, More of a problem would be places that heat up but d not have much draught.
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