It’s difficult to comprehend the difference in Voltages and Wire Gauge (diameter of electrical wire), so we’re going to talk about them in terms everyone dislikes … TRAFFIC.
If you ever looked at the power lines distributing power throughout the country you will see signs warning of danger. They will be marked at 10,000 Volts, 30,000 Volts, and even 100,000 Volts. Why does the U.S. almost always use 115 Volts, while the rest of the World uses 230 Volt? The issue is Electrical Power and Money.
Power in electrical terms is Voltage multiplied by Current (also called Amperage). The formula is P=VI. P is for Power, V for Voltage and I for … Current? Nobody said engineers make sense.
To make electrical things work, they need power, or on a scientific scale, they need electrons, lots of electrons flowing through the wire supplying devices that use electrons to make them operate, such as lights, motors, computers, etc.
Think of one electron as a pickup truck travelling on a road which, in this case, the road is wire. One electron has so much energy available to do so much work. In our case we measure the potential to do the work in volts, and in this case it is 115 volts. When demand is high, i.e. you plug in something that takes a great deal of pickup trucks (electrons) to operate, and if your road is narrow (small gauge wire), the result is that the road is going to get into a traffic jam. What is occurring is that all of these vehicles (electrons) are trying to get to their destination – the thing you plugged in – find that there is not enough room for them on the narrow road (the thin gage wire) and the road jams up causing it to literally overheat, tripping a breaker, and the lights go out – nothing works.
As an alternative we can raise the potential to do work of each pickup truck (electron) by doubling the voltage to 230 volts and pass fewer electrons to the destination but with each electron having double the potential energy to do the required work, and therefore there will be no traffic jam and the narrow wire will get the job done.
You can also spend a lot of money making bigger roads. By bigger roads we mean wire of a greater diameter, therefore able to pass more vehicles (electrons) for a given potential to do the work (voltage). And just like it is in the highway system, bigger roads cost more money. Copper is expensive and since P=VI is a direct formula, the rest of the world decided to double the voltage, in order to use half the size of wire in order to save money on the wire. Unfortunately 230V can kill, so take it with a grain of salt what value the rest of the world puts on lives. We admit that this last line is a bit heavy, but that approximately explains how it happened.
Electrical utilities jack up the voltage to tens of thousands volts, even in some cases over 100,000 volts to ship power across the country on relatively thin wire and then transform (think of it as a train yard where cargo is unloaded onto pick-up trucks) that power to something useable (115V) in your living room.