What are the advantages of a ground referenced power grid vs. a floating grid?
Mostly static electricity protection.
If the grid was floating, it could accumulate enormous charge with respect to ground, leading to serious problems.
You mean the high voltage (over 7.5 kV) side? Lightning protection, from what I’ve heard. Though I must admit I do not understand enough about lightning protection to explain why it is advantageous to reference it to earth ground.
The 120/240 V side of the transformer, of course, *must *be referenced to earth ground. That one is easy to explain.
If it were not ground referenced, then it is possible that a conductor could and would be at extremely high voltage with respect to ground. This would arc across insulation causing failure.
How does that charge accumulate on a floating conductor? What is the mechanism?
Dry wind (especially dusty wind) will generate static charges as it flows over isolated conductors. Also, there is a potential difference from the surface of the earth to the sky - the higher up you go, the bigger the charge. Something like 30v/foot.
Also halves the wiring needed in the grid by using the planet as a neutral return path. I’ve always wondered whether earthworms living near a power station neutral grounding point get a bit of a tingle.
Except, this isn’t done anymore.