How to Connect Outgoing Busway

I agree with your question. There may be a reason for connecting M1 differently from the others, but I don't know why.

What are the small diagonal slashes on two of the PEN lines?

The small diagonal is usually a removable link. As for the rest I'm confused.

Based on the information available to me (which does not include the wiring standard for TN-C-S unfortunately), -S indicates separate neutral and PE conductor configuration where as -C indicates combined neutral and PE conductor configuration, both of which are valid arrangements in the TN-C-S system.

From this I think that -M1 could be a main distribution board (TN-C system with -M1 powering multiple sub-distribution boards) and the other feeders -M2, -M3 and -M4 could be individual sub-distribution boards (TN-S system). -T1 appears to be the source, but if that is so why is the star point connected to -PE instead of -N.

This explains the link in question, however this seems to be an overall system diagram and as such is a little broad (as in incomplete).

Can you provide any more information (including the standards and country this scheme/design is being used in). The more I think about it and the more I re-read your comments the more I think this may be a homework question (spot the mistakes) and not a real system? Perhaps I am reading too much into it.

D/YO Transformer signifies nothing, it should have been something like D/Yn11, thereby "n" stands for neutral and 11 is the vector group.

You have omitted dotted lines encapsulating the busbars A,B,C,N,& E (those signify panel board) otherwise all the five bus bars are distinctly in a panel board and there is no provision of a jumper between neutral and earth bus bars as has been shown.

Neutral of the transformer being a current injector in the event of a fault must go to the earth pit directly , later the earth bar in the board can be connected to the earth pit, separate cable connects neutral of transformer with the neutral bar in the board.

Codes require separate cables from the motor for earth and neutral otherwise in the event of a single wire disconnection one can can get nasty shock and please do realize that there would be two separate distinct earth connections from each equipment.

You seem to have a mixture of earthing systems.

T1 TN-C-S

M1 TN-C

M2 > M4 TN-C-S but wired as TN-S

Are concentric cables used on M1? It could account for it being TN-C