is 16 mm enough for supplying earth to 4 flats?

[bengasman]

Another earth question I can not find the answer to in any of my many books.

Large Victorian house is split into 4 flats.
EDF cable comes in and is split 4 ways, as far as I know: 3 times 100 amp and once 63 amp.

Sheath is connected to MEB with 16 mm, the MEB in then supplies the earth for all 4 flats.
Is 16 mm sufficient here or should it be more?

 

[RF Lighting]

The regs only seem concerned with PME supplies, but it is reasonable to use the same for TN-S supplies.

I ASSuME the incomming neutral will not be greater than 35.0mm², so therefore 16.0mm² should be sufficient.

 

[bengasman]

Great, thanks.
Am not a great assumer myself but true believer in erring on the side of caution. I may be arrogant, but enough of a coward to ask a second opinion if I am not completely sure.