Hi Roland,
The gloves provide virtually no protection against the 480kV
that high power transmission lines run at. (That is about as much as a small
tesla coil will do) The danger when you hang onto a live transsmition line
is that the electric field gradient around you is steep enough to drop many
kilovolts between your head and toes which is why they wear chain mail suits
to even out the field around the persons body.
Nick Field