Plug adapters do not convert voltage; they only allow a foreign plug configuration to be modified to the visiting country's specifications. Plug adapters are usually plastic components that fit over the existing electrical plug. Most foreign appliances will require a plug adapter, but not all will need a voltage converter.
Voltage converters allow electrical equipment with different electrical current requirements to be used with foreign voltage. Converting voltage from 110/120v to 220v is called a "step up" and reversing the conversion is called a "step down" it is wise to purchase a converter that does both. To determine whether or not you will need a voltage converter for your personal items while traveling, check the manufacturer's voltage guidelines either in the operation manual or on the product's website. Items like laptop computers are able to run on both 110/120v and 220v and do not need voltage converters, but you should always double-check before you travel.
You can buy converters in different wattage amounts. According to Travel Oasis, "travelers should not connect a product that exceeds 90 percent of the converter's rated wattage," meaning you should purchase a converter that is greater than your appliance's wattage by at least 10 percent to guarantee safe operation. To determine the wattage of a given product, multiply the voltage by the amps. Both values are printed on the product's manufacturer's label and in the operation manual.
Voltage converters are used for small appliances and are not recommended for long-term use. If you are traveling for an extended period, of time or plan on bringing electronic equipment like televisions, fax machines and other office products, you will need to purchase a voltage transformer. A transformer works just like a voltage converter but is meant to handle the wattage and power surges that accompany large appliances. Also remember that while a converter or a transformer can accommodate several appliances at once with a power strip, you still need to make sure the combined appliance wattage does not go beyond what the transformer can handle.
The cost of a voltage converter depends on the rated wattage amount. Plug adapters are generally inexpensive and are often sold in sets that include different foreign plug configurations. If you are traveling on a budget, you can always check with your hotel or accommodations on whether it provides voltage converters, before you purchase your own.
