The field strength is the Killer, literally. A 7200 line as typical for service around here only has around a 1-2' field around the cable that if you as a ground enter will Arc TO You(Easiest source to ground), where I worked was 345kv, had a SEVEN Foot Circumferential Field where anything got within seven feet it would be incorporated into that field, that is why birds do not fly close to the big Hi Lines as they can Feel that field. Grounding only does so much as generally is done at both ends of a dead cable, anything metal in contact or close proximity will still build static charges that have to be dissipated or can be life threatening. We lost a Electrician at my previous employer to that, he grabbed a recently Ungrounded cable that had built a static charge(DC) popped him and killed him wile still grounded at the Other end. The Earth magnetic field can build a charge in long lays of cable, to the level can be Several HUNDREDS of DC Volts and will still kill you if you are grounded.
