IMO a lot of people would size the conductor I am asking about based on the 40 amp fuse which would be 10 AWG copper which will be correct on the load side of that 60 amp disconnect.
I wanted to point out that the EGC on the supply side of the 60 amp disconnect will need to be based on the 400 OCP.
That would normally be a 3 AWG but for this application, will only need to be 8 AWG as the supply conductors are only 8 AWG.
I thought Georges example was perfect for pointing all this out,
only a little off topic.