The recent post about generators and neutral bonding to ground reminded me of a thread I read on another forum a couple of years ago, it was very interesting and caused a lot of controversy.
The writer explained a demonstration he had seen during a basic course on electricity at a local community college.
The instructor took the class outside to a grassy area where he produced a car battery, a copper rod a couple of feet long, two single strands of (single conductor) wire, one three feet long, the other about 20 feet long and a car headlamp.
He pushed the copper rod into the ground and with the three foot single strand of wire, connected the copper ground rod to the negative terminal of the battery.
He then connected one end of the longer wire to the positive terminal of the battery and the other end of the same wire to one of the two terminals of the headlamp bulb.
Then he touched the second terminal of the bulb to one of those pop-up lawn sprinkler heads that (he told them later) was screwed onto a metal pipe that came up out of the ground.
Of course, you are way ahead of me, to the astonishment of the class, the lamp lit.
He explained that the earth, and any conductor attached to it, was indeed the second conductor along with the one wire leading to the lamp.
In reality, the lamp would light if it was touched to any metal item that was "grounded" and he found other grounded items and proved it to the class.
Of course, he then disconnected the wire going from the battery to the ground rod and repeated the tests, and the lamp refused to light.
He explained that when the battery was "Grounded" that any other grounded item in the vicinity appeared "Hot" to the light bulb. (That is an interesting observation right there, that to the bulb, the earth appeared "hot".)
He stated that with the battery "not grounded" that the only way to light the lamp was to run a second wire to the bulb.
Eventually, he got around to stating that operating an electric drill (metal cased drill) while standing barefoot in a water puddle was perfectly safe if the drill was being powered by an ungrounded portable generator.
He explained that with the generator "Not" grounded, in order to get shocked you would have to actually come into contact with both wires coming from the generator.
However, he said that if you grounded the generator, you would have to come into contact with only the hot wire coming from the generator and "ANY" other conductor or surface that was grounded, which made that situation much more dangerous.