Thesafety aspect is its simply much harder to shock yourself with 120, and when you do its no big. The economy aspect, higher voltages require less wire for the same power. This is why transmission lines are all high voltage, they allow a great deal of power to be transmitted a long way using relatively thin wire.
WorldVoltages. The world runs in two voltage ranges: 110-127V or 220-240V. If your device falls within either range, variations within that range won’t be a problem for short-term use. If the local power is 110V, for example, and your device lists its input at 125V, it will work.

Now the difference in cost of wiring and components 220v will cost more as you need two 110v legs. So 220v circuits will costs 2x (or more depending on gauge) as much to install compared to a 110v circuit. Say you had a 110v hot tub and a 220v hot tub. The 220v hot tub will heat up 2x faster than the 110v but use the same amount of energy.

Its worth noting that dual voltage motors typically report different specifications for 50Hz vs 60Hz operation, which is significant. If they're dual-voltage motors (center-tapped windings), this may lead to confusion about the performance differences being related to the different voltages when, in fact, it is more likely the numbers
Evropase ve 20. letech minulého století rozhodla pro sjednocení energetické sítě, z poměrně nízkého napětí se tak přešlo na vyšší. Potom, co v České republice ale ještě v 90. letech proudilo v zásuvkách 220 voltů (V) a na západě v Anglii a ve Francii 240 V, stanovil se kompromis 230 V s 10% odchylkou. Původní A115-volt air conditioner will supply less cooling power than a 230-volt unit. Cooling is calculated in British Thermal Units, or BTUs as they are commonly abbreviated. Typically, the highest amount of BTU cooling power supplied by a 115-volt unit is about 12,000, while a 230-volt unit can supply up to 24,000 BTUs of cooling. tZQ35. 509 648 251 447 15 527 407 752

220v vs 230v vs 240v