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CSA of main earthing conductor for TT

Grumpy
Morning! Has the minimum CSA of the main earth to the rod changed in the 18th ed? I can't find any reference to it in the BBB (except when buried). 

I have a guy who is insisting on 16mm whereas I "thought" it could be much less if not buried and protected against corrosion and mechanical damage. I only have table 4.4(ii) in my 17th ed OSG as corroboration. Thanks.
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    Sparkingchip:

    There are some very involved answers to a simple question.


    Table 54.1 says it is 2.5 mm2 provided the cable has a sheath and is protected against mechanical damage.


    16 mm2 if it has a sheath, but is not protected against mechanical damage.


    25 mm2 if it does not have a sheath and is not protected against mechanical damage.


    Andy B.


    Table 54.1 applies to a BURIED earthing conductor. Grumpy was interested in an earthing conductor to a rod which was NOT buried.


    Z.


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  • 0
    Sparkingchip:

    There are some very involved answers to a simple question.


    Table 54.1 says it is 2.5 mm2 provided the cable has a sheath and is protected against mechanical damage.


    16 mm2 if it has a sheath, but is not protected against mechanical damage.


    25 mm2 if it does not have a sheath and is not protected against mechanical damage.


    Andy B.


    Table 54.1 applies to a BURIED earthing conductor. Grumpy was interested in an earthing conductor to a rod which was NOT buried.


    Z.


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