I need to know what conductor size I must use to meet 17th edition. I
found a table at
http://www.tlc-direct.co.uk/Book/5.4.3.htm
but I'm far from clear about what column's what.

The installation is:
tails 25mm^2
earthing TN-S
No RCD
Main bond conductor length 12m
Install age: early 1980s

Can someone explain the columns?


thanks,
NT