Here is what the FAR
's have to say (at least pt 91) about Minimum Safe Altitudes:
Sec. 91.119 — Minimum safe altitudes: General.
Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes:
(a) Anywhere. An altitude allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface.
(b) Over congested areas. Over any congested area of a city, town, or settlement, or over any open air assembly of persons, an altitude of 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet of the aircraft.
(c) Over other than congested areas. An altitude of 500 feet above the surface, except over open water or sparsely populated areas. In those cases, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure.
(d) Helicopters, powered parachutes, and weight-shift-control aircraft. If the operation is conducted without hazard to persons or property on the surface—
(1) A helicopter may be operated at less than the minimums prescribed in paragraph (b) or (c) of this section, provided each person operating the helicopter complies with any routes or altitudes specifically prescribed for helicopters by the FAA; and
(2) A powered parachute or weight-shift-control aircraft may be operated at less than the minimums prescribed in paragraph (c) of this section.
The parts of this section that apply are: A and C.
As far as A is concerned, he is operating in open fields so I would say he could carry out a landing without undue hazard to persons or property. As for C, he is in sparsely populated areas, so the entirety of legality pretty much comes down to if you consider a power line a "structure". Even if it is considered a structure, pretty much everyone is going to turn a blind eye to it.
EDIT: See below
[Edited 2012-03-21 10:01:19]