Why Do Some Countries Use 120V Power While Others Use 240V?

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One of the big challenges to home charging in the United States is that homes and garages often just don’t have good power for Level 2 charging. There may be a plug right near where you park your car, and that’s often true for apartment buildings and even multi-level parking garages. But, that plug is often a 120-volt plug with wiring that can only support 15 or 20 amps. That puts a limit on available charging to about 1.4 kW (to leave room for safety).

But, European wall outlets are a lot nicer in this regard. They’re often limited to 13 or 16 amps, but at 230 volts, we’re talking about around 3 kW of power. This is roughly twice as powerful as a US outlet. Most drivers would probably want a 7+ kW charger if they’re doing a dedicated charger installation, but getting by with 3 kW of power is a lot easier than trying to rely on only 1.4 kW of charging power in the US.

Most newer US homes have 240V power available at the breaker box and wiring for that power goes to receptacles for stoves, ovens, clothes dryers, and water heaters. But, adding an EV charging circuit often requires running a whole new set of wires from the breaker box, which may or may not have enough overhead for charging to begin with.

Europe also has a lot more access to three-phase power, which leads to even faster AC charging being available (up to 22 kW).

All of this puts US EV drivers at a pretty good disadvantage. So, we have to ask ourselves why one of the wealthiest and most powerful countries on the planet be like this? It turns out that there’s some interesting history behind this that goes back to the 19th century. (article continues after embedded video)

It all starts out in Chicago in 1878. Thomas Edison went to see a guy who had invented a generator that could put out enough power for up to 8 high-powered arc lamps. This excited Edison (who was more of an investor than an inventor), but he didn’t think arc lights would be very popular because they were just too damned bright. So, he decided to look into other options. With the light bulbs his team pioneered, he figured that he could power cities’ worth of lower-power bulbs with just a few of these dynamos.

Sadly, the generator he found in Chicago didn’t turn out to be great, so he did what all wealthy tech investors do and went into Borg mode, buying up every generator design he could get people to sell him. Elements from each of these designs were cobbled together into a better generator. It just so happened that the first generator his team started with was set up for 110 volts, and this configuration survived the testing and improvement process.

Years later, when Edison’s first power plant went online, he found that some power lines had people using more lights than others. This, of course, increased the resistance on those lines. So, to keep voltage from sagging and lights going dim on busier lines, Edison doubled up the 110-volt generators, and ran a third wire out to those areas. Customers’ circuits would go from one of the main lines to a new third neutral wire to get the 110 volts and complete the circuit. This allowed Edison to balance out circuits and use less wire for the system overall (and copper was expensive in those days, too).

Another cool thing about this setup was that it also offered 220-volt power along the same wires. By running a circuit from the two hot wires instead of hot to neutral, you could get twice as much wattage for something like an electric motor. By the time all this was worked out, the industry had already standardized on 11o volts for light bulbs, so it didn’t make sense to make individual light sockets and outlets use the higher voltage. This then led to basically the whole United States sticking with that format.

But, the landscape changed in 1904. Another team figured out how to make better tungsten-filament bulbs, which in turn allowed for 220 volt circuits to run light bulbs. European power companies saw that this could be beneficial, because you could send twice as much power over the same wires using that higher voltage. Some even paid customers to switch to better bulbs so that they could upgrade all of the circuits to 220 volts and skip the 11o-volt middle man.

The United States already had such a demand for light bulbs that new tungsten bulb production couldn’t keep up. What made U.S. light bulb demand so high? The explosive growth of Chicago. When Chicago became the railroad and water transportation hub of the Midwest, it jumped into the millions, with the most explosive growth of the city happening right in the middle of this change from 110 volts to 220 volts.

Then, on top of the growth, there was the Great Chicago Fire. When basically the whole downtown burned to the ground, the whole area was rebuilt from the ground up with new building technology, and this happened at a time when 110 volts was the standard. The world’s fair and all of these new buildings ended up spreading the building practices of Chicago out all over the United States. Tall buildings couldn’t safely use gas lighting, so electric lights became the standard.

So, many people kept buying older bulbs that couldn’t handle higher voltages just so they could keep the lights in all of the new buildings and houses that were springing up in Chicago. Other countries were building power systems from scratch and weren’t experiencing explosive population growth, and thus didn’t have this baggage get stuck in the proverbial carousel.

In other words, because the U.S. was an early adopter of electric lighting in a city experiencing crazy population growth, it got stuck with an earlier version of the technology. By the time tungsten bulbs were widely available, the industry had already built too many 110-volt circuits to want to switch over. So, 11o-volt tungsten bulbs were produced.

At this point, all of the major world empires were European, with the United States only taking an interest in North and Central America. So, countries supplied by European companies went with 220 volts while countries supplied by the United States went with what the Americans were selling.

After this, power companies decided to start upping the voltage to make their systems more efficient while still supporting existing devices. 220 volts became 230 and 240. 110 volts became 115, 120, and even 127 volts. The only country to drop its voltage was Japan, who had adopted American 110V power, but lowered it to 100V due to fear of fire (which would be utterly devastating to Japanese architecture of the time).

Featured image by Jennifer Sensiba.


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