I'm using a GPSMAP 64st. It report consistently 10' accuracy. I'm doing waypoint averaging for receptacles and meters and often double check them over several days to minimize errors. I have GLONASS and WAAS turned on. The power lines are already in the ground but do not appear on any "map" therefore they are unprotected. My only purpose with this is to document locations and directions to provide to any locator so they can do their jobs easier rather than guessing. It's a tool that works "good enough" for the purpose and being able to zoom down to 20' or so would really help and expand the possible uses. I do not strictly rely on the GPS data and often double check the results, but it makes life so much easier to have the reference tracks.