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In Brazil I have visited a number of cities where every house is wired with 220v. This is a FULL 220v between the Live and the Neutral, plus the Ground wire. Very different from the 220 in the US where you get two Live wires with 110v and a Neutral.

Everyone in one of these towns have to buy special bulbs, clothes iron, hair dryers, blenders -- that is anything that has a a resistance to produce heat and motors.

But for laptops and phones it is a completely different story -- they all work well on both 110v and 220v -- as you might have seen on the label of your phone charger. And here comes the interesting piece -- they do not work equally as well -- they charge your laptop/phone in approximately half of the time.

Questions are:

  1. Is it possible to wire such a circuit in the US?
  2. Is connecting the two live wires to Phase and Neutral on a normal outlet, produce someting that will allow phone chargers to work?
  3. Is it legal?

I am aware of the slightly related question here as well as of the existance of step-up transformers and the 20 Amp - 250 Volt outlet:

20amp - 250volt outlet

but I can't stick my iPhone charger into it.

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  • of course you cannot plug your phone charger into that outlet ... that is to prevent "120 V only" devices from being plugged in
    – jsotola
    Commented Apr 25, 2022 at 1:53
  • 3
    Citation needed for "they charge your laptop/phone in approximately half of the time." - the limiting factor is typically output-side voltage/current, not the primary/input side. I have a USB C charger right in front of me that is specified to do USB PD 9V@3A, and it achieves its nameplace spec perfectly happily on a 110 V outlet. Also, not sure where in the US you live, but we have 220V already wired for our electric vehicles, dryers, stoves, etc.
    – nanofarad
    Commented Apr 25, 2022 at 3:15
  • @jsotola phone charges are NOT "120 V only" the are 120/220.
    – TeX Apprentice
    Commented Apr 25, 2022 at 3:17
  • @nanofarad I have 220v in the house as well (electric vehicle, dryer, stove & air conditioning), but it is totally different 220v from the one I described above. Here in the US it is: L1 (110) + L2 (110) + Ground. There it is: L (220) + Neural + Ground. My phone works there. The questions is if it will work the same here.
    – TeX Apprentice
    Commented Apr 25, 2022 at 3:28
  • @TeXApprentice NEMA-14 provides L1/L2/neutral/ground, so there's a discrepancy somewhere in the question. I don't even understand the premise of the question - why would a two-terminal device such as a double-insulated phone charger actually care about anything other than a potential difference?
    – nanofarad
    Commented Apr 25, 2022 at 3:31

2 Answers 2

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Having mains with 220-240VAC at the plug is quite normal in many parts of the world. It is just different what you are used to and in fact not that interesting.

Contary to your claim the phone and laptop chargers are not chargers but only power supplies and they do not charge in half the time when plugged into 220VAC. These will provide exactly same amount of power out, and take approximately same amount of power in, except for minor differences due to the fact that the efficiency can vary slightly because of the input voltage. As the input voltage is double, it takes in half the current, to charge something at constant power.

From the laptop power supply point of view, it does not matter how it receives 220VAC, with wires named live and neutral or with wires named live and live.

The problem is only that common household sockets in US are wired for 110VAC and while 220VAC sockets do exist tey only exist for special high power purposes and standard plugs are not compatible with them for obvious reasons.

So the answers:

  1. Yes, it is possible, nothing prevents you from wiring 220VAC sockets, except the fact that it is unnecessary to begin with, and you must use the correct wall socket type to prevent plugging in 110VAC equipment, and you must use a custom adapter for your devices and these are obviously dangerous as they allow plugging 220VAC into 110VAC devices. And it may not be up to electrical codes and regulations.

  2. Yes, devices that accept 220VAC can work but dangerous due to reasons above, but don't use a standard plug.

  3. You can have a legal 220VAC socket if you want, just not 220VAC on a standard 110VAC socket. But it is just not needed at all. Your 110V mains sockets charge your phone and laptop just as fast as in 220V socket.

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  • 1
    Chargers that claim 100-240V input, but perform differently when powered off 110V or 220V in fact do exist and are not that much rare. They are simply of low quality and should not be used at neither voltage because of other risks related to low quality electronics (e.g. fire hazard or damaging the connected devices).
    – fraxinus
    Commented Apr 25, 2022 at 8:08
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    US voltages have been 120/240 nominal for nigh onto 50 years at this point. 110/220 and 115/230 are quaint relics of a bygone era. And yes, if your charger works faster on 240, it's likely counterfeit junk that will probably catch on fire at either input voltage. An actual iPhone charger puts out the same DC volts and current at any rated input voltage.
    – Ecnerwal
    Commented Apr 25, 2022 at 14:48
  • @Ecnerwal My Apple 18W USB-C power adapter says Output: 5V/3A or 9V/2A. The 20W USB-C (also from Apple) says: Output 5V/3A or 9V/2.22A. You can check both labels here. Commented Apr 25, 2022 at 17:35
  • 3
    So, you don't understand USB charging standards. Whether it puts out 9V or 5V depends on what the device connected to it says (or does not say) when they negotiate the charging voltage, NOT what the primary voltage into the charger is. switchchargers.com/what-is-fast-charging
    – Ecnerwal
    Commented Apr 25, 2022 at 17:40
  • I have a hair dryer labeled as universal but it's a trick ... it just runs half as hot in 120V countries. Just a marketing con. Aside from that I've never seen or heard of a dual voltage device that works "better" on one voltage or the other. You will not get better performance out of anything by wiring up a "Brazilesque" outlet. If you have a 220 or 240V device, you MUST install an appropriate outlet. If you have a universal device (like a laptop PSU) you can do whatever you want and it will, as promised do exactly what it does. Don't waste your time.
    – jay613
    Commented Apr 25, 2022 at 19:21
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And here comes the interesting piece -- they do not work equally as well -- they charge your laptop/phone in approximately half of the time.

No. Either your testing is very flawed (e.g. "feels like" instead of the Scientific Method) - or your charging blocks are very cheap garbage. I use genuine Apple charging blocks, the 12W unit designed for the iPad, I get them on eBay.

I have a feeling this notion comes from a limited understanding of how older power supplies work - the ones with big transformers. Everything else is confirmation bias. That is wrong, switching power supplies operate on a completely different principle and work on any voltage > their output voltage. (with the proviso that too low input voltage means too much input current, and they may not be built for that much current).

I am aware of the slightly related question here as well as of the existance of step-up transformers and the 20 Amp - 250 Volt outlet:

Yes, we have a whole collection of 240V receptacles, and you're welcome to install as many of them as you like into your home.

enter image description here

As you can see, they are nothing special, and they slot right into normal junction boxes and use normal wires. You can even have many such outlets on a circuit, the rules are the same as for 120V outlets (except these must add on to the required 120V outlets, not replace them).

but I can't stick my iPhone charger into it.

Then get an iPhone charger with a 240V plug on it. Note that on the 12W iPad units, the plug is changeable. But your premise is false, it won't make your phone charge any faster.

Is connecting the two live wires to Phase and Neutral on a normal outlet, produce someting that will allow phone chargers to work?
Is it legal?

Heck no, you can bet it's not. It creates an incredibly dangerous situation where some time after you do it, either you forget that your outlet is tainted, or someone else comes along. They plug a 120V device in there and #1 it catches fire and blows up. Or #2 the polarized appliance is built with less shock protection on neutral, and yours has -120V on it, so they get killed.

If you are hellbound and determined to energize a NEMA 5 socket at 240V, then go get one of those cruddy Chinese step-up transformers that has the "universal everything socket" on the front which will take NEMA 5. Cell phone chargers are about the limit of those everything sockets. And it's obviously a step-up transformer, so anyone who plugs a 120V load in there has no one to blame but themselves.

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  • Can you really install a CEE7/4 ("schuko") legally in the US ?
    – fraxinus
    Commented Apr 26, 2022 at 11:25
  • @fraxinus I don't see why not... if it's UL or CSA/US listed. The government doesn't say "you shall only use NEMA". Depending on what our treaties say exactly, TUV or BSI might be enough even without a /US. Commented Apr 26, 2022 at 17:25
  • Good to know. Thanks.
    – fraxinus
    Commented Apr 27, 2022 at 21:02

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