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I'm going to be traveling from the EU to the USA for a few days. During my stay, I need to be able to charge personal devices such as my laptop, my phone, and my shaving machine.

Coming from a country with 230V and 50Hz power, what off-the-shelf equipment am I going to need to use the 120V and 60Hz network in the US?

(I see adapters on Amazon that convert the shape of the plug but they explicitly mention that they don't convert voltage or frequency, so I'm a bit puzzled about their usefulness.)

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    Which country are you in? "The EU" is a collection of countries, which use different plug standards. As of today, the UK is still an EU member - but we use different plug to those in, for example France. – Chris Melville Jan 28 at 9:58
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    @ChrisMelville It doesn't really matter. Everywhere in the EU uses 230V, which is the problem being asked about. – thelem Jan 28 at 11:43
  • Check your devices. Most of them will most likely work with 110 V, and then you just need a plug adapter. – Thorbjørn Ravn Andersen Jan 29 at 19:41
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The first thing to do is check all your appliances. Check wether they are multi voltage. You will see that printed on them somewhere. I have yet to encounter a laptop or mobile phone charger that was not good for 100-250V, 50-60Hz. Those kinds of adaptors have been accepting a wide range of AC voltages and frequencies by default for a long time.

The shaver may or may not be an issue. If it is a battery powered one, with a charger, then in all likelihood that charger will accept any voltage as well.

If all your appliance are of the "any voltage" kind, than all you need is a plug adaptor that adapts the shape of your EU plug so that it fits in a US socket.

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    This answer does not address the issue "how do I check if my laptop is 100-250 V, 50-60 Hz". It is as simple as "it should be written on a label on the charger", but it may not be obvious for the OP. – Federico Poloni Jan 29 at 12:28
  • Don't just check the voltage, but the frequency too. Incorrect frequency might result in anything from a device running too quickly, to it becoming very unreliable. Additionally, be aware that some plug adapters are earthed (the third round prong on the US plug) and some aren't. If you have a device that requires earthing, make sure the adapter passes this through too. For shavers, I've often seen a 220V/230V supply in a bathroom in North America for this purpose. But it's not guaranteed. – Dan Jan 29 at 14:19
  • @Dan Where did you see that? In my experience in the US, 220V outlets are pretty much almost exclusively used (at least in residential installations) for cooking appliances and clothes dryers. (I know someone who plugs their Tesla into one to charge as well.) Never seen a 220V outlet in a bathroom. – Darrel Hoffman Jan 29 at 15:30
  • @DarrelHoffman Hotels and some airport bathrooms. Usually with a sticker saying "220V only" or similar. But not universal by any means. Perhaps I just stay in places a lot of business travellers do who might benefit from that. – Dan Jan 29 at 15:54
  • @Dan Hotels and airports, maybe. It's essentially unheard of in private homes business settings though, apart from the aforementioned large appliances. – Sebastian Lenartowicz Jan 29 at 16:45
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As others have said, almost all laptop and phone chargers will support 100-250V at 50 or 60Hz. They have switch mode power supplies, which for various technical reasons I won't go into, are very easy to build to support all the world's major domestic voltage and frequency standards, so almost all of them are built as such. Check on the chargers themselves to be sure. It's also quite likely your shaver will support this; again, check on it to be sure. If this is the case, a travel adaptor would be sufficient, converting the shape of the plug only.

However, a word of warning. I would also suggest buying from a reputable retailer in your home country (maybe an online one), and not from a site like Amazon or eBay where a huge variety of companies can sell things claiming to be other things with limited policing, and where fakes are common. Sure, in all likelihood there won't be a problem, but I wouldn't want to be putting myself in danger of electrocution or fire, which are both certainly possibilities based on the horrific adaptors I've seen in the past. On the other hand, things bought in reputable retail stores or from the websites thereof are generally quite good at complying with all relevant electrical safety regulations. Even if it costs a bit more, to me this is worth the peace of mind.

On a similar note, buy one that is solely designed to convert US sockets for EU plugs. These tend to be a lot more sturdy and safe than the ones designed to convert anything to anything.

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    Note that many of the anything to anything converters can end up exposing hot contacts. – Loren Pechtel Jan 28 at 2:51
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    Depending on the laptop you might be able to get a US figure of eight cable, or the bit that slides on to the power charger for a mac laptop when you get there. If you are planning on repeat trips its worth it for the convenience/not having to chose been charging your laptop or your phone. – tallus Jan 28 at 10:21
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    It’s safe to buy from Amazon as long as you’re buying from Amazon themselves, and not from a third party using the Amazon marketplace. – Mike Scott Jan 28 at 10:23
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    @MikeScott it's quite often difficult to tell these days whether you're actually buying from Amazon or from a third party. The third parties are given equal footing in search results and a lot of them have Prime now as well. – Muzer Jan 28 at 10:50
  • Almost all? is that just to hedge your bet or do you really know of any laptop or smartphone of say the last decade or two that wouldn't support 110 and 220V? Given the economies of scale in modern manufacturing and as you say the simplicity of supporting both, I'd find an example fascinating. – Voo Jan 29 at 17:27
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I see adapters on Amazon that convert the shape of the plug but they explicitly mention that they don't convert voltage or frequency, so I'm a bit puzzled about their usefulness.

This is called an Adapter: The European plug will be adaped to the US power plug (it will not convert the 240V to 110V AC power source) .

Most (if not all of all) Laptops can switch automatically between the 2 (dual-voltage), so only a plug Adapter is needed.

For your phone, which will probably be based on a USB-Charger, the plug Adapter can also be used.

For your shaving machine you will have to look at the label.
If it states: "110-240V~/50-60Hz" (dual-voltage), then a plug Adapter can also be used.
(A quick search shows that many do, but make sure that 60 Hz required in the US is also supported) .

Not using a Converter (where needed) from a 240V (European) appliance to the 110V (US) should cause no harm, it will just not recieve enough energy to work properly (the raser may run slower).

The answer linked below gives many useful details about the whole topic.


Sources:

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    That razor looks like it has an universal power adaptor, and I would expect it to work in the US without issues. Just get a plug adaptor. – Krist van Besien Jan 27 at 12:45
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    @Tor-EinarJarnbjo suggesting it will not be an issue when the manufacturer states it is not an issue dos not deserver a -1... Most modern AC-DC power supplies are switched supplies, and they can operate on pretty much anything. This is good for the manufacturer, who does not have to design a different power supply for each market, and good for the consumer. – Krist van Besien Jan 27 at 15:12
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    @MarkJohnson I do not know what you learned in Electrical Engineering, but the summary of the page you are linking to is 'it depends'. To keep it simple and talk about common travel related appliances, a 240V hair dryer may for example very quickly catch fire if used on 110V. The heating element will operate at a bit more than ¼ of the rated power, but the fan may not start at all, making ¼ of the rated power more than enough to melt or even ignite the mountings of the heating element since there is no air flow to cool them. – Tor-Einar Jarnbjo Jan 27 at 15:53
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    I've blown up my fair share of power supplies and other computer components. They're certainly noxious, but never anything in sufficient quantity to be toxic and certainly not "very toxic" in a single instance. – T.J.L. Jan 27 at 20:11
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    Yeah... that'd require a whole lot more burning cable than letting the magic smoke out of one device by plugging it in wrong. In sufficient quantities, water is toxic, too. – T.J.L. Jan 27 at 20:23

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