If using an external DC wallwart style psu would the 0v line still get tied to the chassis as the common ‘star’ point? Obviously if it was mains level voltage then the safety earth would be connected to the chassis for safety reasons.

I’m looking at making a project using the following PSU and usually I would use a mains toroidal in the box etc hence linking in the safety earth but using an external one is new to me.

https://docs.rs-online.com/5f27/0900766b81673010.pdf

 

Depends on what is the function of the apparatus.
There are different types of ground and 0V and not necessarily need to be connected to chassis.

1) Earth ground that gets connected to your electric utility and bonded to mother earth
2) Chassis ground which is a metallic or conductive enclosure
3) Signal ground or common which is any reference node in an electrical circuit
4) Then there is analog ground and digital ground which are meant to keep signal paths separate

Along with the above we have double insulated power tools that have no ground connection.

 

Is the 'Star' point mentioned, the usual equipment enclosure earth GND point?
Earth ground is not usually carried through or bonded to the -ve output side of a Wall-Wart, Do you need to bond the DC common to earth GND? If so you would need to pick up an earth GND from the outlet etc.
Or is this just a concern of ensuring the enclosure is earth bonded without the W.W. supply also bonded?
Is it needed in this particular case?

 

That power supply has a 2-pin input, so no earth connection. That means you will be connecting your chassis to mains live via a 2.2nF capacitor.