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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
    Yes, de rating factors if you like


    First have a read of Appendix 4, section 7.1 where it relates to installation method D


    Then take the data for "BICC" installations in Amtech and apply that to the BS 7671 data for all the parameters you list (noting Table 4B4 doesn't have a correction for 0.8m depth of lay)


    Check if BS 7671 is applying the Factor Cc of 0.9 for all buried cables (direct or in ducts) as Equation 1 in 5.1.1 in Appendix 4


    If you still have a difference, put it down to manufacturers testing being mare accurate than BS 7671 values which may have 5% variations used (and up to 10% on buried cables) which tend to be on the conservative size


    As a sanity check, see if your calculations show more than 10% variation, which may well be the Cc factor above which BICC data doesn't use (although it may be applied equally by Amtech to either case)


    I've run calculations using BICC data and BS 7671 data with very good agreement of out turn cable size - so it may be an Amtech glitch


    Regards


    OMS




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  • Former Community Member
    0 Former Community Member
    Yes, de rating factors if you like


    First have a read of Appendix 4, section 7.1 where it relates to installation method D


    Then take the data for "BICC" installations in Amtech and apply that to the BS 7671 data for all the parameters you list (noting Table 4B4 doesn't have a correction for 0.8m depth of lay)


    Check if BS 7671 is applying the Factor Cc of 0.9 for all buried cables (direct or in ducts) as Equation 1 in 5.1.1 in Appendix 4


    If you still have a difference, put it down to manufacturers testing being mare accurate than BS 7671 values which may have 5% variations used (and up to 10% on buried cables) which tend to be on the conservative size


    As a sanity check, see if your calculations show more than 10% variation, which may well be the Cc factor above which BICC data doesn't use (although it may be applied equally by Amtech to either case)


    I've run calculations using BICC data and BS 7671 data with very good agreement of out turn cable size - so it may be an Amtech glitch


    Regards


    OMS




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