Time to define terms.
VOLTAGE is the FORCE pushing the electrons through the wire.
AMPERAGE is the AMOUNT of electrical current in the wire. Think of a water pipe. You apply
pressure to push the water through the pipe. As a result a
volume of water flows through the pipe. Force is required to push the water because of friction between the water and pipe walls. In a similar manner friction prevents electrons from freely flowing through a conductor thus they, like the water, have to be
pushed. Electrical resistance is measured in
OHMS. Conductors, like copper, steel, aluminum, etc. have very low amounts of friction to electron movement while non-conductors (a misnomer, actually insulators) offer a very high amount of friction to electron movement. Dry air, e.g., is an excellent insulator requiring 76,200 volts to ionize the air enough to carry a 1 inch (2.54cm) spark.
The standard utility pole in the United States is about 40 ft (12 m) long and is buried about 6 ft (2 m) in the ground.
So a "body" be it bird or bear cannot hold/contain voltage and discharging through the air to the ground impossible (unless you have 31,000,000 volts)
Ok so far so good, now the wires on the poles. Once again let's define terms:
Distribution lines carry power from local substations to customers. They generally carry voltages from 4.6 to 33 kilovolts (kV) for distances up to thirty miles, and include transformers to step the voltage down from the primary voltage of the lines to the lower secondary voltage used by the customer. A service drop carries this lower voltage to the customer's premises.
Subtransmission lines carry higher voltage power from regional substations to local substations. They usually carry 46 kV, 69 kV, or 115 kV for distances up to 60 miles.
On poles carrying both, the electric power
distribution lines and associated equipment are mounted at the top of the pole above the communication cables, for safety. The wires themselves are
uninsulated, and are supported by insulators, usually porcelain,(although wood is a non-conductor WET wood can conduct thus the insulators), commonly mounted on a horizontal crossarm. Power is transmitted using the three-phase system, with three wires, or phases, labeled "A", "B", and "C".
At the power station, an electrical generator converts mechanical power into a set of three AC electric currents, one from each coil (or winding) of the generator. The windings are arranged such that the currents vary sinusoidally at the same frequency but with the peaks and troughs of their wave forms offset to provide three complementary currents with a phase separation of one-third cycle (120°). The generator frequency is typically 50 or 60 Hz, varying by country.
At the power station, transformers change the voltage from generators to a level suitable for transmission.
After further voltage conversions in the transmission network, the voltage is finally transformed to the standard utilization before power is supplied to customers.
Most automotive alternators generate three phase AC and rectify it to DC with a diode bridge.
Now,
Subtransmission lines comprise only these 3 wires, plus sometimes
an overhead ground wire (OGW), also called a "static line" or a "neutral", suspended above them. The OGW acts like a lightning rod, providing a low resistance path to ground, thus protecting the phase conductors from atmospheric static discharges.
The pole itself may also be grounded with a heavy bare copper or copper-clad steel wire running down the pole, attached to the metal pin supporting each insulator, and at the bottom connected to a metal rod driven into the ground. Some countries ground every pole while others only ground every fifth pole and any pole with a transformer on it. This provides a path for leakage currents across the surface of the insulators to get to ground, preventing the current from flowing through the wooden pole which could cause a fire or shock hazard. It provides similar protection in case of flashovers and lightning strikes.
OK, at last anything, bird, chimp, or bear touching any of these transmission lines is totally safe
UNLESS a ground wire is also touched
at the same time. If our poor bear touched the subtansmission line
PLUS the OGW above it or any other wire plus the poles grounding wire at the same time, he's gonna fry.