A guide to power converters for laptop use overseas

If one of your users is heading overseas with his laptop, you'll need to do your homework on power converters.

When one of your users – or you – heads overseas, one thing to remember is that the electrical current might be different than what you're used to. Electrical outlets in most countries use different voltage circuits than what the United States uses. Travelers with notebook computers should look into acquiring a power converter.

Until recently, I had never had to use my notebook with a different type of current. Either I was traveling abroad on vacation and left my laptop at home, or else I was on business but staying in a hotel that offered Americanized power outlets.

However, as I prepared for a recent business trip overseas, there was no getting around the need for a power converter. Thinking that getting a power converter would be simple, I bought a universal power adapter from a local chain. I thought I was all set. But when I got home, I noticed that the box said the power converter was not suitable for class 1 electronics. This meant the power converter wasn't suitable for use with laptops, digital cameras or MP3 players. Apparently, the universal converter was not so universal after all.

After doing some research, I discovered that different types of voltage adapters are created for different purposes. In the United States, electrical outlets provide 110 volts of AC power, operating at 60 hertz. However, most of the rest of the world uses 220- or 250-volt circuits operating at 50 hertz. Plug shapes, plug holes and plug sizes also differ by country.

Many of the less expensive adapters on the market simply allow you to plug a device with an American-style plug into a foreign power outlet. But you can only get away with doing that if you're using a dual-voltage appliance. For example, many hair dryers and curling irons include a transformer that can accept 110-volt or 220-volt power. If an appliance has a dual-voltage transformer, you can use this type of adapter and operate the device directly off of the foreign power supply.

But any device that does not have a dual-voltage transformer (including most laptops) will be severely damaged or destroyed if you plug it into a 220-volt outlet using an adapter. For anything without a dual-voltage transformer, you'll need a voltage converter that includes a step-down transformer. A step-down transformer converts 220-volt power to 110-volt power.

Not all voltage converters are suitable for all jobs. Converters are generally classified as high wattage (0 to 2000 watts) or low wattage (0 to 50 watts). Some converters include a switch that you can use to toggle between high- and low-wattage modes.

Power converters differ for electrical and electronic devices

When it comes to picking out a power converter, there's a big distinction between electrical and electronic devices. Electrical appliances include shavers, curling irons and electric razors; electronic appliances include laptops and digital cameras. Electronic appliances tend to be much more sensitive than electric appliances. Oddly, some devices that you might think of as electronic are actually classified as electric and can be used with low-wattage converters. Examples include calculators and CD players.

Note: Most converters are not suitable for use with your electronic devices. They're primarily intended for use with electrical appliances. You can use the wattage listed on an electric appliance to determine whether you need to use a high- or low-wattage converter. If the wattage isn't listed, you can calculate it by multiplying volts by amps.

If you're traveling with a laptop or other electronic device, use a converter that's rated for use with electronic devices. These types of converters, although similar to high- and low-wattage converters, provide much greater control and conditioning of the power supply. I recommend checking the wattage of your laptop's power supply and getting a transformer that supplies 10% more wattage than what your laptop requires. Otherwise, the transformer may be inadequate.

One last word of caution: Many European hotel rooms have an American-style 110-volt outlet in the bathroom. Never plug anything other than a low-wattage electrical appliance into this outlet. The outlet lacks the power conditioning necessary for safely powering electronic devices. It also lacks the wattage necessary for powering higher wattage devices, such as hair dryers.

About the author: Brien M. Posey, MCSE, is a Microsoft Most Valuable Professional for his work with Windows 2000 Server, Exchange Server and IIS. He has served as CIO for a nationwide chain of hospitals and was once in charge of IT security for Fort Knox. He writes regularly for SearchWinComputing.com and other TechTarget sites.

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This was first published in August 2007

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