16 mm t+e feeding submain

[daz1963]

Hi all. been to look at a job where power is required for a garage. need to go back and take a second look. but on first visit i noticed a fully loaded second consumer unit in the kitchen feeding a number of circuits,from a main consumer unit next to the dno cutout feed with 16 mm t+e. i'm assuming its just using the earth in the t+e as the main earth. is that acceptable or should there be a seperate earth say at 10mm. seen this in a number of flats so assumed to be ok but not comfortable with it. just looking for your views on this? Its a t-n-s set up by the way.
many thanks in advance Daz...

 

[malcolmsanford]

Adiabatic equation and all will be revealed

 

[spud1]

Chances are no not satisfactory, especially if main protective bonding relying on that 16mm cpc but you must confirm with Adiabatic equation as malc says