I'm planning to buy a Siemens coffee machine from Europe. It uses 220-240V 50Hz. Previous models work just fine in USA using 240V outlet (my electrician was able to get it done, I bought leviton 5031-w).

Recent models are different and apparently use internal timers that rely on frequency and therefore the machine won't work--it displays this message: Power supply frequency is out of range.

I tried to find outlets that claim to be 220V/50Hz and found these:

Do they convert the 60Hz to 50Hz, or how do they operate exactly? Is that all I need?

I appreciate your assistance.

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    Is your model of coffee machine not available in a 120/60 version?
    – Huesmann
    Commented Mar 22, 2023 at 13:48
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    You should ask Siemens help desk why they enforce the 50Hz requirement, and add the answer to your question. It is interesting. Also can you tell us why this coffee machine suits you better than any one sold for the US market? I know people want European tea kettles because they work much faster, but I don't know of any reason a European coffee maker would be better than a similar US-marketed one.
    – jay613
    Commented Mar 22, 2023 at 17:36
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    Euro teakettles work faster because they have higher wattage to work with; its not inherent to the kettle design. If you plugged one into a 120V/15A circuit (common for US households), it would be just as slow as a teakettle sold for the US market. As to the coffeemaker, the only difference could be the quality of the coffee it produces, which has nothing at all to do with the electrical supply.
    – asgallant
    Commented Mar 22, 2023 at 21:51
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    @jay613 It's probably a market segmentation strategy on the part of Bosch/Siemens. Perhaps the US version is sold at a significantly higher price, or the model is not on the US market at all (e.g. to avoid cannibalizing sales of more expensive models). Perhaps the brand is positioned as a premium one on the US market? (It's entirely average in the EU.)
    – TooTea
    Commented Mar 23, 2023 at 9:00
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    @Anis what's the model of the machine?
    – jay613
    Commented Mar 23, 2023 at 13:04

7 Answers 7


TL;DR A different receptacle will not change voltage, frequency or anything about the electricity. It just changes the physical configuration.

But there are devices to change voltage and/or frequency. It gets complicated...

It is easy to change voltage. In fact, your utility sends electricity at thousands of volts and it is converted to 120/240 in the US, varying but similar voltage elsewhere in the world. For a long time there have been small travel transformers to convert, for example, 240V to 120V so that a traveling American could use their small appliances around the world or Europeans to use their small appliances in the US. And since most US homes have either 240V or 208V power available, it is not that hard to wire up an appropriate receptacle for European appliances.

However, frequency is a different story altogether. It is hard to change frequency. In fact one of the easiest ways might be a double conversion UPS - AC 60Hz to DC to AC 50 Hz, but I don't know if anyone makes such a device for routine use at a reasonable price.

For a lot of things, frequency hardly matters. The most common issue that I am aware of is not timing - typical appliances now use digital timers that don't care about line frequency at all. It is large motors, which will run at the wrong speed and might have major problems. I suspect the frequency detection you found isn't about getting timing right but about making sure you don't have motor problems.

Unless there is a great need (one of a kind medical device?) I highly recommend getting an appliance that is either designed for 60 Hz or flexible 50/60 Hz.

To address the issue of voltage, hot, neutral, etc. which has been discussed extensively in comments:

Most typical AC-powered consumer devices - lights, heaters, computers, coffee makers, vacuum cleaners, toasters, TVs, etc. - around the world today are designed for, broadly speaking, one of two power ranges:

  • 100V - 125V - This covers US/Canada, Japan and a number of other places. There is variance by country and also historical. For example, typical equipment (appliances, receptacles, switches, etc.) for the US/Canada are rated for 125V (or more) but the typical voltage is 120V and many devices still reference 110V.
  • 200V - 250V - This covers Europe, most of Asia, most of Africa, etc. It also covers US/Canada. The US/Canada standard split phase system delivers 120V between hot and neutral and either 208V or 240V (with some variance allowed there as well) between two hots. In places where 230V is the base consumer voltage then it is between hot and neutral with some higher voltage (e.g., 400V) between pairs of hots.

Some equipment, such as laptop power adapters, can actually use the entire 100V - 250V range.

Without a ground or neutral specific reference, there is no practical way for a device to "know" whether it is on a 240V system (like Europe) or on a 120V/240V system (like US/Canada). And it doesn't actually matter.

Where it can matter is safety. In the US/Canada (but not necessarily everywhere else) neutral and ground are bonded. Which means that if neutral and ground touch each other and you have a metal case that is bonded to ground, nothing will happen. That can be good for safety (a properly wired US/Canada light fixture with bulb sockets is installed so that the more accessible part of the socket is neutral rather than hot, which makes changing light bulbs relatively safe even if the hot wire is live), but in some cases (3-wire dryer connections with a broken neutral and a wet floor) be very dangerous.

But since many non-US/Canada systems don't have grounded receptacles everywhere (they still aren't everywhere in the US/Canada but most houses have plenty of them even if they still have some two-wire receptacles) and many systems are not polarized to force the hot/neutral configuration, best practice is to design consumer equipment for international use in one of a few ways:

  • Both current carrying conductors fully insulated from any user access (i.e., little fingers).
  • Plastic case or, if metal is used then no intentional contact between any current-carrying conductors or other "live" components and the case.

If built properly (and that is the job of UL, ETL, etc. to make sure equipment is designed and built properly) then the end result is that ~200V - ~250V equipment can be used in different countries around the world with the only change needed being the power cord/plug. Computers and many other consumer electronics take advantage of this by using a removable cord and including a different cord depending on the destination. Notably, some low-end laser printers include a permanently attached cord and that actually makes sense because while the control electronics are identical for 100V - 250V, the fuser (a heater that melts the toner onto the paper) is generally different for ~120V vs. ~240V.

The one exception to "anything 200V - 250V is pretty much the same everywhere" is frequency. Which is where this all started.


No they do not convert the frequency.

  • 4
    There's more to the question than that. It's also asked implicitly what else is needed to use the device.
    – isherwood
    Commented Mar 22, 2023 at 20:45
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    Then the question title ought to at least attempt to cover that, instead of the trivial matter of installing another kind of outlet. Commented Mar 25, 2023 at 14:51

No, sockets don't change frequency. Changing frequency requires very complex electronics comparable to a VFD (Variable Frequency Drive). Basically a DC power supply coupled to a DC/AC inverter. The thing would be the size of a toaster and have cooling fans.

I would consult with the factory on whether they would support 60 Hz.

Coffee makers are resistance heaters and DC electronics. Neither one cares what the frequency is. It's not a "clock" thing. If it was, the coffee maker would work and then do everything 18% faster. They have silicon electronics in there, which runs on DC, and they have added circuitry and cost to allow them to detect the frequency. They have done that for a reason.

Obviously some coffee maker manufacturers are taking a big stand on 60Hz operation, and other manufacturers are not. The answer is "To heck with the ones who impede you". Deny them your business.

Your other option is to use a European online UPS - the specific kind that does not have a transfer switch, but runs in inverter mode all the time and has an AC-DC converter supplying the DC to the inverter. Since this type is DC-coupled (and does not care what the input frequency is), it will cheerfully make 50Hz all day and not know it's not in Europe.

You may ask yourself "why are you proposing a box with an AC-DC converter, DC-AC converter and a battery when the battery is superfluous to this task?" The answer is "economies of scale". UPS's are sold by the millions. 50Hz-locked VFDs, not so much.

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    I think for the total amount of money needed for a sufficiently large online UPS plus all the other bits of this "solution" including the electrician and the machine itself ... I'd rather fly to Italy, have a nice cup of coffee there, and I could probably do that about 4 times.
    – jay613
    Commented Mar 23, 2023 at 14:41
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    The other way that frequency conversion is (or at least was) done is going via kinetic energy rather than via DC, using two AC motor/generators connected by a shaft. Apart from being noisy, it's far too inefficient to use for appliances like this (it's mostly useful for connecting different grids together, where the power flow can be in either direction). Commented Mar 23, 2023 at 16:51
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    @Toby Or simpler, a rotary converter, which is DC-coupled and considerably less copper windings than an M-G set. Although, more brushes. The local power company says "we know when you run it because it corrects power factor for half the county!" Unfortunately the art of making them is probably lost. Commented Mar 23, 2023 at 19:46
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    To heck with the ones who impede you". Deny them your business. => another option is to hack their device and force it to work the way you want it to. Even more satisfaction if you ask me. Commented Mar 24, 2023 at 3:57
  • Many UPSs will auto-select the output frequency based on input. The hardware for 50 & 60Hz is essentially identical and having a different input & output frequency means you can't use a mechanical or internal bypass in the event of a UPS fault. I'm pretty sure that would throw an error on any serious UPS. Commented Mar 24, 2023 at 8:41

The wall plug is a dumb device.

Behind the cover it has some wires going in and bringing Power(Voltage and current). On the other side it is the plug you see where you plug in.

It does noting other than bringing the power from one side to the other side without changing anything.


Can be described as how often the power goes on and off (yes it does that)

It does that very very fast so you do not notice. We call that Alternating power.

It is measured in Hertz. In US it does that at 60 Herz, means 60 times per second. In Europe it does that at 50 Hertz. It is so fast you can not see it since our eyes are to slow for that. If you could see it you would see the lights flicker.


The outlet is nothing but wire terminals assembled in a case so a plug can have "proper" connection. Some outlets have a security fuse or breaker.

None of above do anything to voltage, frequency or any other property of the mains.

The only thing that will chage after replacing the outlet with outlet used in EU is this: You will need to use european plugs.

You technically can use the outlet for 230V 50Hz, 220V 60Hz, 110V 60Hz and even for 24VDC, 12VDC or any other of your choice.

BUT it will be as wise as cleaning your ears with a rusty nail.

You know, if you see european outlet you expect it is powered to european standard, if you see U.S. outlet, you expect american standard.

If you want to achieve 60Hz to 50Hz conversion you need dedicated AC-DC-AC converter.

  • 1
    "if you see european outlet you expect it is powered to european standard, if you see U.S. outlet, you expect american standard." - I answered a question a while ago where someone replaced a 240V outlet with a 120V outlet (same wiring) and plugged in some 120V appliance and it went bang. That is why the 240V outlets are different from the 120V outlets. Commented Mar 25, 2023 at 6:35

Those 'outlets' will absolutely NOT change voltage or frequency. They are just very pricey custom outlets for specific installation.

A power supply that converts 60 to 50 hz will be expensive. How much current does the coffee maker require? $1000-1500 would not shock me.

  • 2
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    – Community Bot
    Commented Mar 22, 2023 at 8:21
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    50Hz invertors are readily available, so one just needs the appropriate 60Hz AC to enough DC input device. Way less than $1000.
    – Jon Custer
    Commented Mar 22, 2023 at 12:56
  • question did not ask about changing voltage.
    – Nelson
    Commented Mar 23, 2023 at 0:51
  • @JonCuster I don't drink coffee but think coffee machines use heating elements to boil water so running one from an inverter might need a quite big inverter Commented Mar 23, 2023 at 4:12
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    @JonCuster OP wants to import a fairly fancy European machine. I just checked and ours is 1600W, and dual boiler ones are considerably higher - this one is listed at 2200W. Commented Mar 24, 2023 at 9:06

No, a simple power outlet will not change the frequency. The outlets you mentioned in the question are just power outlets with extra protection in some specific environments (either wet or with dangerous chemicals), but they seem overpriced to me.

To convert the frequency you would need a device such as this one: https://www.amazon.com/220-Volt-50Hz-Power-Source/dp/B091JDHJH3/ (this is not a recommendation to buy, it's just a sample to see how it is supposed to look like). However, this seems to me like too much trouble just to have some coffee.

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