Getting foreign gadgets to play nice with the local power grid is a nightmare any time you travel internationally. Here's why every country on the planet (except yours) totally screwed up indoor wiring.
In the early days of the electricity craze, just after Nikola Tesla and the Westinghouse company wiped the floor with Thomas Edison's DC power scheme, inventors around the world began working on ways to harness the fantastical energy for household work. Everybody had a different idea of how to do so. In fact, when Westinghouse standardized its operating frequency 60 Hz, it snuffed out nine other potential frequencies. The same is true for the worldwide standard of 120 and 220-240V systems—these two beat out ten other options to become the de facto voltages.
However, Germany paid little heed to the US's choice of a 60 Hz frequency. They instead decided on a 50 Hz standard because that's what was already being used by the BEW company, which held a monopoly on German power generation and transmission, in 1899. The 50 Hz scheme spread through Europe while the 60 Hz spread through North America. They became competing, nearly-universal standards—120V at 60Hz in North America, 220-240V at 50 Hz in Europe.
The other problem with early electrical systems: There was no easy way to tap into the power supplying small appliances. If you had a table lamp or a hair dryer or some other low voltage gadget, you'd have to knock down a wall and hard-wire it into the house's electrical grid. Amateur inventor Harvey Hubbell is credited with creating the first appliance with a "Separable Attachment Plug." However, instead of the cord remaining attached to the device, it would be hard wired into the system and would disconnect from the base of the gadget.
While Hubble's preliminary plug and socket design prevented access to live wires from the home grid, many other inventors stepped up to improve his pioneering design to reduce shock and fire risks through the inclusion of grounding and electrically insulated pins, polarized shapes, and additional cut-off switches.
The most momentous of these added features arrived in 1928 at the hands of Philip F. Labre. Until then, it was uncomfortably common to receive an electrical shock when removing plugs because the pins (or prongs) would short easily short when the plug was partially pulled out of the outlet. The electrical current could travel through the person into the ground. By integrating a third pin slightly longer than the other two, Labre was able to direct all potential short circuits safely to the ground rather than through a person.
The problem with Labre's design is that the triangular plug can be inserted into the socket in three different ways, two of which are wrong. This creates what's known as an unpolarized plug. So engineers developed plugs that could only be fully inserted into a socket when properly oriented, thus guaranteeing a safe, polarized connection.
There are a few ways to design such a plug. In North America, prongs are different shapes and sizes. In Europe, they are angled so that the plug only fits in one way. Throughout Asia, the shape of the prongs dictate how the plug fits into the outlet.
While plugs and outlets the world over all share the same basic safety features (for the most part) how those features are implemented varies by region and country. Here's a quick rundown of the plugs in your neighborhood.
The US, Canada, and Mexico rely on two standardized plug styles (of the 13 such primary standards) known as Type A and B. Type A plugs—aka NEMA 1-15s—use a pair of 15A, 125V ungrounded prongs. These are common throughout North America and along the South American Eastern seaboard and have been polarized since the 1950's, though many older homes still use the unpolarized outlets. More recently, the Type B (or NEMA 5-15) grounded standard has been adopted. They are very similar in shape to the Type A's and also work at 15A, 125V but they also include a ground pin. In addition to North and Central America, you can also find these plugs throughout the Caribbean, Colombia, Ecuador, Venezuela, Japan, Taiwan, the Philippines and Saudi Arabia.
Fun fact: In the mid 1950s, the US government briefly entertained the thought of converting its 120V system to match that of the European standard. While the US never actually made the switch, the US implemented Edison's old three-wire system—the positive 120V wire, the negative 0V wire, and a third -120V wire so that heavy home appliances like refrigerators and washing machines could access the larger 240V range (known as Class II appliances) without overloading smaller voltage appliances that ran on the 120V standard (Class I appliances).
Many outlets in North American bathrooms, where appliances like hairdryers, electric shavers, and other accessories are commonly used around water, are now outfitted with Ground Fault Circuit Interrupters (GFCI) receptacles. You can spot these sockets by their red and yellow "reset" and "test" buttons on the cover. These devices measure the flow current, and if a sharp difference is detected, kill the power supply to the outlet, before the electrical short hits you.
Most of Europe uses the Type C plug, more commonly known as the Europlug, utilizes a pair of cylindrical, unpolarized prongs and is used almost exclusively by devices that require 2.5A or less. It is employed throughout the continent as well as the Middle East, Africa, some parts of South America, central Asia, and the many ex-Soviet satellite states.
But Germany, on the other hand, uses the Type F "Schuko" 16A, 250V outlet. It looks a lot like the Type C except that it is polarized through the inclusion of a pair of grounding clips. Other Schuko users: Albania, Austria, Bosnia and Herzegovina, Bulgaria, Chile, Croatia, Denmark, Estonia, Finland, Germany, Greece, Hungary, Iceland, Indonesia, Iran, Italy, Latvia, Lithuania, Luxembourg, Republic of Macedonia, the Netherlands, Norway, Pakistan, Portugal, Romania, Russia, Serbia, Slovenia, South Korea, Spain, Sweden, Turkey, Ukraine, and Uruguay.
Most of the United Kingdom relies on Type G (aka British Standards 1363 or BS1363) plugs for its power. This pin uses a trio of grounded, polarized pins set in a triangular shape with an integrated safety fuse. This makes them among the safest (and most cumbersome) on the planet. The United Kingdom, the Republic of Ireland, and Hong Kong use the Type G. Cyprus, some parts of Malaysia, Singapore and Saudi Arabia also use plugs compatible with this standard.
In Switzerland, folks use 10A, 250V Type J plugs. These closely resemble Europlugs, however they are not necessarily insulated per the Swiss standard. To compensate for this shock hazard, outlets throughout Switzerland are recessed into the wall to minimize the danger.
And in Italy, people use the Type L, which allows for either a 10A or 16A receptacle with differing prong diameters.