From Wired How-To Wiki
All electricity is not created equal. In fact, the world is full of varying voltages and Hertz levels that make traveling with electronic devices somewhat complicated.
This is perhaps the most complex problem gadget geeks headed abroad will face -- sorting out all the different requirements for one's gear. Do you just need a wall adapter? An adapter and a voltage converter? And what about a surge protector?
Fear not -- this guide should answer those questions.
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What's the Deal with Electricity?
Worldwide voltages range from around 110 to 240. Plug a device expecting 110 into a wall outlet delivery 240 and you can easily end up with a melted hunk of plastic and burned out circuits.
Fortunately, newer electronics are often able to handle a wide range of voltages. You know those tiny print labels on all your battery chargers that you've always ignored? Time to pull them out and have a closer look.
The text you're interested in is the voltage rating, which, if you're lucky, says "100V - 240V." If yours says just 110V or just 240V, you're going to need a voltage converter. When it comes to voltage converters, the best option is to buy one that covers the whole range. Voltage converters can be found at just about any online retailer which sells electronics.
Also bear in mind (if you happen to be a war correspondent) that Afghanistan and few other countries sometimes have voltages up to 280V, so you may want a converter that can handle more than 240V.
If voltage wasn't enough to worry about, the world's electricity supplies also deliver varying degrees of Hertz. Generally speaking, the options range between 50-60Hz.
So again, pull out those chargers and check to see how many Hz they can handle. Now, if you need to, you can buy a voltage adapter that spans 100V-240V and 50Hz-60Hz.
Guide to World Electrical Systems
How do you know what you're going to encounter at your destination? Just look it up in this indispensable chart of electricity around the world. The table on that page lists every country and displays the voltage, Hertz and the type of wall adapter necessary.
Also, check out Wired's gallery of electrical conduits and plugs from around the world.
Plugging it In
The last and simplest concern for travelers totting high tech gear is a good set of travel plug adapters.
A plug adaptor is a relatively simple little gadget that will allow you to plug an appliance designed for one type of outlet into another type of outlet. Generally, you can buy plug adaptors in kits of five or six plugs.
If you take a look at one of the many guides to all the wall socket types in the world, you'll notice that there's over a dozen -- so how come adapter kits have fewer options? The answer is that you average travel adapter kit ignores the grounding wire.
While that's not necessarily a bad thing, it is important to remember that unless you spring for a grounded adapter, there will be no grounding, which creates some potential safety concerns. For most short terms uses, like recharging your laptop or camera battery, you can get by without the grounding. If you're planning a long term stay abroad, you should probably grab some grounding adapters.
Unfortunately it can be somewhat difficult to come by grounding adapters outside the area in question. Your best bet may be to buy one at an electronics shop when you get to your destination. It may also be much cheaper to do it that way.
Another thing to keep in mind if you're coming from the U.S.: not all type A outlets are the same. In the States, we've mainly switched over to polarized outlets, where one hole is slightly larger than the other to accommodate the slightly larger plug blade. (The larger plug blade is the neutral side of the current).
Unfortunately, not every country that uses type A outlets has switched to polarized wall outlets. That means that if you devices have a larger blade in one side you may still need an adapter to fit an older, non-enlarged, Type A wall unit.
Beware the AC/DC
There is one final concern when plugging things in abroad -- direct current (DC) outlets. Although DC is rare, it does exist and will most definitely fry your gear. If you're unsure if a particular outlet is DC, ask someone at your hotel or guesthouse. I've been to 23 countries on three continents and never encountered a DC outlet, but there are some still hanging around.
Watts and Surge Protectors
Travel surge protectors can be had from most of the same places that sell adapters. Sometimes you can even find surge protectors that come with adapters. A travel surge protector is essentially the same as your usual power strip, though it generally only offers one or two plugs to conserve on space and weight.
Most geek gadgets -- laptops, digital camera batteries and the like -- operate in the 75-200 watt range. To find out exactly how many watts your devices use, look on the power plug label, consult the manual or use this formula:
Volts(AC input) x Amps(amperage) = Watts (Wattage)
110V x .5 amps = 55 watt
When you're looking at at voltage converters, keep this number in mind since different converters can power different wattages.
Also bear in mind that heating appliances such as hair dryers (as well as irons, coffee makers and more) need a 1600-watt converter. Good to know if you're the type that has to maintain the well-coifed Flock of Seagulls hair 'do even when you're traveling.
Although it's not a bad thing to buy some of this stuff ahead of time, it may, in some cases, be cheaper to find abroad -- especially if you're headed to Asia.
Also be aware that not all adapter/voltage/surge kits are created equal. I bought an rather expensive combo unit in the States that blew up in Paris. I bought another expensive one in Paris and it blew up in Nepal. Finally I bought a cheap, all-in-one unit for $2 on the street in Bangkok and it has lasted for four years now.