Answer / 7anoter4

It depends on many factors:
For continue load:
insulation maximum permissible temperature: pvc-70 dgr.C
XLPE,EPR-90 dgr.C
conductor material-copper or aluminum
cable routing: open air, in conduit, cable tray, underground
[buried, ducts] and so on.
ambient temperature: air[30-40 dgr.C], earth [20-25]
thermal resistance of the earth
other[like shield losses, conduit losses and other]
In the IEC World IEC 60287 could be a guide.
In USA the J.H.Neher and M.H.McGrath publication could be a
guide:
"The Calculation of the Temperature Rise and Load
Capability of Cable Systems"
For short-time[as in short-circuit case]it depends on
insulation maximum permissible temperature[140 pvc, 250
xlpe,epr] ,conductor material and the duration of the load.

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