Can I Use My Hair Straightners in the USA?
The answer depends on which straighteners you have as some are dual voltage and others are not. If yours are dual voltage thet will say something along the lines of "110/240V 50/60Hz" somewhere on the appliance. If they don't then you can safely assume that they were not made to operate on 110V.
(Or anywhere else that uses 110V)
If They are Dual Voltage
Take them with you, they will be fine. Mark IV GHDs and later should all be dual voltage. You will however need a travel adaptor in order to plug them in and you have to be a little bit careful if you want to remain safe. There are two important points that you need to consider:
You can also get universal adaptors in either earthed or unearthed forms if you want a more flexible solution. Again you need to check that they can handle the current before using one.
Do they need to be earthed? If so you will need an earthed adaptor (one that has 3 pins instead of two). How do you tell? The easiest way is to look at the plug that came with the device. If the top pin (which is the earth) is plastic then it doesn't need earthing. If it is metal then assume that it does need to be earthed. Standard GHDs for example do not need earthing. This is what we would recommend if you need a dedicated earthed adaptor.
How much current do they draw? Cheap adaptors that you may get in a pound shop are cheap for a reason. Usually they are rated for a very low current - maybe just 1 or 2 amps and they often will not even give a rating on the packaging so you can't even tell.
Working out the current that a pair of hair straighteners will draw is not so simple either. We have seen GHDs which claim that they use 35 watts. Whilst they may only use 35 watts once they are up to temperature you can bet that they use a whole lot more in the initial warm up, in fact we've seen measurements of 300 watts. On a UK supply of 240V 300 watts will only require 1.25 amps but when you try to extract the same amount of power out of a 110V supply it will draw 2.7 amps which will likely be more than a cheap adaptor is comfortable handling. You may get away with it as it is not drawing this current over an extended time, but then again you may set fire to your hotel room! here's a decent unearthed adaptor that can handle the current.
If They are not Dual Voltage
In theory it should not be dangerous to try it and they should just take longer to heat up and not get as hot. In practice however we have heard of it causing damage to the straighteners which then need to be repaired or replaced so we would not recommend it. Mark 3 GHDs and earlier are not dual voltage. If you really can't live without your straighteners then you have three options:
Buy a cheap set when you get there.
Treat yourself to a new set of dual voltage straighteners before you leave.
You can take a transformer to convert the 110V to 230V (the frequency 50/60Hz will not matter). But, and its a big but, it will cost nearly as much as a decent set of straighteners, is bulky and heavy (around 5 kg).
It is generally recommended that you choose a transformer with a power output around 25% greater than the peak draw of the appliance which means that you will need this kind of step up transformer. Even this says that it is not powerful enough for hair straighteners but we think that they are probably being over cautious as long as your peak power is not over 350 watts (check your instruction booklet). The next one up in size is this which frankly justifies its own suitcase.