EGC

[kwired]

Since NEC does not state how to use the conduit as EGC Georgia Tech Research Institute presented the research[1994] entitled:
Modeling and Testing of Steel EMT, IMC and RIGID (GRC) Conduit
https://steeltubeinstitute.org/steel-conduit/wp-content/uploads/sites/4/2014/12/GROUNDIN.pdf
According to Table 6.1 Maximum System Length (Predicted by Model for Comparison to Soares - 50 Volt Arc and 500% of Protective Device Rating) for 1/2"emt 280 ft it would be the maximum length.

I did not look through all that, but think I know what the idea is, sort of no different then upsizing a conductor for voltage drop reasons.

I will tell you I have seen many times on irrigation applications where we often have long circuit lengths (though is usually underground in non metallic conduit) an overcurrent device doesn't trip on a ground fault but rather some component fails under the fault current, or at very least the overcurrent device takes a while to trip because the fault current is limited by circuit resistance. This happens even with EGC that is the same size as the ungrounded conductors.

That said, outside of some control conductors at times, the power conductors in those situations are large enough a 1/2 or even 1 inch raceway is out of the question.