voltage adaptor

What you are talking about is a voltage converter. An "adapter" is the gadget that allows you to plug an electrical cord into an outlet that has a different configuration. See this very helpful page that not only discusses different electrical systems, but differentiates between electrical appliances and electronic devices: http://www.rei.com/learn/expert-advice/world-electricity-guide.html I think you might regret buying and lugging a voltage converter to use your own hair dryer overseas. Those can be like lugging a brick, and all too often they end up not working, or frying themselves or worse yet frying your hair dryer. This is my experience from researching the subject and from observing fellow travelers a few times. Heat producing electrical appliances like hair dryers are the biggest power-suckers, and it's not just voltage you have to deal with, it's wattage. I hope some electrical engineer can explain it better. If you must have a good hair dryer for your 2 weeks abroad - I strongly advise that you don't waste money on a voltage converter. Spend your money instead to buy a hair dryer that is designed and built to be used with the electrical systems in Europe. Either shop online for one, or wait till you get there and buy one there. Also, if you haven't tried one of those microfiber towels (a bit bigger than a hand towel) for drying your hair, run don't walk and get one, and take it with you. Cuts way down the blow-drying time! (The brand I have is Aquis, purchased at BB&B.) I know you want to enjoy yourself in France, and not feel frustrated about your hair, or uncomfortable. I hope you get it figured out and have a great time!

I'm a mechanical engineer, not an electrical engineer, but in my career I designed plenty of electro-mechanical appliances. Think of voltage as the pressure in a garden hose and current ( amperage) as the flow rate. Wattage is the voltage times current. In a resistive device, such as the heating elements in your hair dryer, the current drawn is voltage/R (resistance). The heat produced is V2/R. (That should be V squared, but ETBD's BBC doesn't support superscripts.) A single voltage device would draw four times the amps, and produce four times the heat, at twice the voltage. Dual voltage hairdryers just switch the resistance heaters between series and parallel so that each of two heaters always sees 115V. A common hairdryer might draw 12 amps at 125 volts, which is 1500 watts. Since most home circuits in this country are protected to 15 amps, you can't use a device with more than about 1500 watts without blowing the breaker. I once tried to use my hairdryer at a hotel in London and the breaker blew. When I looked in the breaker box, it was a 5 amp breaker (1200W at 240V); my hair dryer drew more than 5 amps. BTW, how do you know that the hotel supplied hairdryer will not work. Have you been there before.

Many of us that travel a lot use a dual-voltage hair dryer. They sell them all over. Just Google dual-voltage hair dryers and you will see where to buy one. I purchased mine from REI and it has a dial to switch between voltages. Which I switch over before I leave home. They are not that expensive Here is a link for the various adapters needed around the world: http://electricaloutlet.org/ You can buy them at Walmart and various other stores. I always carry extras just in case I leave one behind or need more than 1 or 2.

In this country, some UL required safety protection is provided by either a grounding plug (third round pin), a polarized plug (one blade wider than the other), or occasionally by double insulation (square-in-a-square symbol, equal width blades). Electrical receptacles in continental Europe do not provide for polarization, so that protection can be lost. Realistically, you don't need that protection in most cases. Americans use polarized hairdryers in Europe all the time without a problem. A few hairdryers might be double insulated. This would be the preferred hair dryer to use in France.

I found a Revlon dual voltage at Marshalls for $16, and just tried it out, but it seemed to fry my thick, curly hair. I assume the hotel dryer will be even worse quality. I won't bother bringing one that is not dual voltage. I am hoping to find a high quality dryer that I could use at home and when traveling, but understand it must be dual voltage, now. Has anyone found anything that worked well?
Thanks!