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BICC or BS7671 comply for design

Anthony Sullivan
Hello IET guys 


I have a problem where a cable installed on site doesn't comply to Bs7671 current  carrying capacity for underground cable reference method D 


the engineer who design the cable used amtech and data from bicc with reference method 110. 


Dose bicc comply? As its old data for cables install in any country from what I can see. I would have thought bs7671 design must be used? 

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  • Former Community Member
    0 Former Community Member
    Ok - a quick check on that cable at 1m depth, in ducts, not grouped or spaced, at ground temperature of 15C and soil thermal resistivity of 1.2K.m/W in air ambient of 30C suggest a 1 x 4C x 95mm2 (copper) with SWA and XLPE insulation (ie 90C) can carry about 260A - so greater than the device rating of 250A without further setting.


    You will need to make a demand on the 90C operation however, unless you can get that MCCB down to around 220A if you operate at 70C - which seems to be the case anyway, by the nature of the load


    As a quick check the cable is around 65C at 220A


    Personally speaking, it looks OK at the first pass


    Regards


    OMS






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  • Former Community Member
    0 Former Community Member
    Ok - a quick check on that cable at 1m depth, in ducts, not grouped or spaced, at ground temperature of 15C and soil thermal resistivity of 1.2K.m/W in air ambient of 30C suggest a 1 x 4C x 95mm2 (copper) with SWA and XLPE insulation (ie 90C) can carry about 260A - so greater than the device rating of 250A without further setting.


    You will need to make a demand on the 90C operation however, unless you can get that MCCB down to around 220A if you operate at 70C - which seems to be the case anyway, by the nature of the load


    As a quick check the cable is around 65C at 220A


    Personally speaking, it looks OK at the first pass


    Regards


    OMS






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