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SWA in U/F floor slab

whjohnson
Got a job where a new submain - approx 25 metre run in 16mm 3 core SWA. Embedded directly into a new concrete floor where wet U/F heating will be installed. Am trying to work out the best order of installation - that is, should the cable go in first, then the insulation, followed by the U/F pipework,and finally followed by the slab. Am not sure what order the u/f heating side will be installed and am also thinking about how if any correction factors may need to be applied for the current carrying capacity. I have sized the cable with a little overhead in mind in terms of actual final demand, but am still a little concerned about final slab operating temperature

Comments welcome.

PS - Am not liking this new format - it is like writing inside a letterbox when compiling posts!
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    the electric mat underfloor heating (100-200 watts per m2) typically sets the floor temperature limit stat in the range 28 to 35 degrees, so not much derating for that sort of system


    If you used 90C SWA cables, but applied the 70C SWA current ratings, then the rating will be OK for almost a 50C ambient, and even in the hot side of the slab it should not really exceed that..

    But if you can, get your cables on the cold side of the insulation.
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  • 0
    the electric mat underfloor heating (100-200 watts per m2) typically sets the floor temperature limit stat in the range 28 to 35 degrees, so not much derating for that sort of system


    If you used 90C SWA cables, but applied the 70C SWA current ratings, then the rating will be OK for almost a 50C ambient, and even in the hot side of the slab it should not really exceed that..

    But if you can, get your cables on the cold side of the insulation.
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