QEX July-August 2016 has a lengthy report on some experiments I performed to check on the validity of NEC modeling for low and buried wires: Download QEXJul-Aug 2016 BOG .
A summary of this article was run in QST June 2016: Download QST June 2016 BOG .
One important comment was omitted from these articles:
The function in NEC which models wire insulation works only for thin layers of insulation, i.e. < one wire diameter and even that is pushing it a bit.
I tried to use this function to model buried radial systems with the wires in plastic tubes. All I got was nonsense! The EZNEC manual is very clear on this point but I couldn't resist trying it anyway!