Traveling abroad in the '60's through 80's, I only had to worry about having extra alkaline batteries, and if my hotel had a bathroom adapter for my electric razor.
Today, my list of travel and photography gear, needing an electrical outlet to work or get charged, seems to go on forever. My travel electrical needs, like so many travelers, is significant.
Just as most every country has its own language, and currency, and definitely its own culture, countries have their own electrical power specifications. Travel photographers, like any traveler, need to be aware of the electrical milieu of the countries they're visiting, so they are prepared for their stay.
There are two basic factors for which travelers must be electrically prepared; voltage and electrical outlet form-factor.
There are two basic standard voltage ranges in the world today, 100-125 volts (North American/Caribbean system), and 220-250 volts (Europe and the rest of the world).
Especially if you're traveling to multiple countries, electrical outlet form-factors are a problem. Magellan's, a leading catalog company specializing in travel gear sells eighteen (18) plug adapters which describes the scope of the outlet problem.
For most devices such as computers, cameras, GPS, battery chargers, mp3 players and alike, you only need worry about voltages, even if you're plugging multiple devices into a single outlet, however, if you're using an iron, or hair drier, all bets are off. These devices suck up a lot of power, so amperage (essentially, the amount of electricity used per second) becomes important. If you're in an old hotel with an electrical circuit rated only for low “amps,” you might blow the fuse or circuit breaker.
Today, manufacturers of most electronic devices, including cameras, cell phones, mp3 players, etc., design them to be “dual voltage,” able to be used in both the North American and European mode electrical systems. Most electric razors are likewise designed, but I can't say the same for hair driers and irons, for example, although there are a few “dual voltage” units available.
For travel photographers voltage generally isn't an issue. For example my Canon charger lists it can handle electrical input from 100–240 V AC-50/60Hz. Likewise, my Nikon EN-EL4a battery charger lists it can handle it too.
That being said, it is critical that you check each electrical device you will bring on your travels to ensure it can handle the full range of electricity you will encounter.
If you have a piece of essential electrical gear which isn't “dual voltage,” you'll need a voltage converter. To choose it, if possible, you should determine the amperage it uses. Hair driers, curling irons, and coffee pots use high amperage, so you'll need a heavy duty converter for them.
TIP: Here's something I learned from the folks at Magellan's. If you use an iron while traveling, please note that many irons don't work properly with voltage converters. You're better off getting a dual voltage iron for international travel.The biggest problem for international travel photographers is the variety of electrical outlet form-factors used throughout the world. Even if your electrical device is “dual voltage,” it doesn't mean its plug will work everywhere. If you're from the US, your plugs won't work in Europe.
When traveling away from your home country, more often than not, you'll need plug adapters to use your electrical devices.
For example, if you were going on a trip from the US to the UK, France, Italy, and Egypt, you'd need five (5) plug adapters (for regular and grounded outlets combined) to ensure you could plug into any outlet you encounter.
Before you leave on any trip, for each country you'll visit, check to determine what plug adapters you need to match their electrical outlets. Play it smart, get both the grounded and non-grounded plug adapters.Like me, you may have need to plug in multiple devices in your hotel room at night to be ready for the next day. I often plug in iPhones, an iPod, my computer, and couple of battery chargers simultaneously. To make that easy, I use a Belkin Mini Surge Protector Dual USB Charger. I can plug in three electrical devices and two USB devices simultaneously to the Belkin, and only need a single plug adapter for it.
Be prepared for the electrical systems you'll encounter to help ensure you'll have a great time during your travels.