A VERY good idea and more relevant now GPS is more accurate (the de-rating of accuracy now removed by US military).
If all wires, posts and pylons were surveyed over a period (maybe during maintenance) then a database (silimar to Jeppeson, or even part of it) could be built up and loaded to any GPS. Even the wires themselves could be shown on the moving map.
Big job? Not as big as putting them all there in the first place and that got done...
All new installations could be entered as they are built as matter of obligation, all exisiting could be surveyed by the firms patrolling, Pilots from every district could send in info. to be ratified by a central mapping agency. All anyone needs to supply their local wire/post info is a GPS and a pen......! Info could even be downloaded to a central computer over the net...All the technology is there right now.
Care would have to be taken that pilots do not become too dependant on such a system and fly into unlisted wires as a result but that would only require the same amount of caution that ALL GPS derived information should be treated with. An EMF proximity warning system could help in that direction too.
I've always thought that EMF would be (should be) easy to detect, one may do it at home (in a crude way) using a $10 microphone connected to any amplifier.
The two systems used in conjunction could be a very important step forward. Wires are a major problem here in NZ (as they are in other Countries). I am going to forward this excellent idea on to NZ CAA right now.
Well done.