Higher voltage = less amperage needed for the same number of watts = smaller cabling can be used.
Same reason most high-speed trains use 25kV (AC). Local trains use 1.5kV (DC), but for the wattage required, the amperage increase would require the overhead cables to be much thicker (and therefore heavier & more expensive to manufacture, install, and support).
Ah, so sacrifice a little safety for a cheaper install?
All building sites use transformers for 110 equipment.
Lower amperage is usually safer, although you're still dead either way past a certain threshold. Smaller cables are also more flexible and therefore less likely to break. Not a big deal in a house, but if it's an overhead wire to power a train, you don't want to be replacing sections all the time.
Usa supports same voltage
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