This is one thing that really gets me going,
we opened the N-E links on a whole street fed with 230/400V MEN and got a Fault Current of 23,000A, tested at the "Consumers Terminals" (The Line-side of the Main Switch).
With the links closed, we had a Fault Current of 36,000A, at the same point.
This was undertaken during an Undergrounding Operation,that I was involved with, a new 11kV transformer being installed mid-street. [Linked Image]