Cable from NER to Earth Pit

See:

IEEE Std 32-1972/1990 IEEE Standard Requirements,Terminology, and Test Procedure for Neutral Grounding Devices.

ch.10. Resistors.10.2 Insulation Levels:

"The line end and ground end insulation levels shall be selected from Table 4 on the basis of fault voltage criteria, Columns 3 and 4."

Yes, remember the earth cable is at or very near ground potential.

It's mentioned in whatever standards you are working to.

What's up? Didn't you buy enough and you have no budget provision for another reel?

The question is not about the budget, my previous projects were using HT cable from Tx to NER, and NER to ground, for this current project, the customer requests to use 2 x 70mm2 earth cable as per their specification...

There may be special reasons for this in your previous projects, that or the consultants didn't know what they were doing (not an uncommon occurrence in my experience).

Why yes Mr consultant I will bail you out of your mess free of charge while you get paid for presenting my work.

Calculate values of fault current for L-G & L-L-G.