When to convert radial lines?

[Jrattray]

As part of scheduling an upgrade of a radial spur to a net worked solution I am trying to get a feel for what is current best practice. The first step will be a presentation to the regulator on what other countries / states do.

I know some jurisdictions go N-1 at 10, 15 or 25 MVA, some on least cost between lost energy and the cost of the upgrade; in the latter using a value for lost energy at about $25,000 a MWh.

What would be appreciated is any thoughts on what is the process outside of Australia.

Thanks in advance for your time