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Benefits are better PSU efficiency (~3%) and higher load on same wire size.

Someone told me it would not work (or break) because the 240v of Europe is not the same as 240v in America, his argument was about phases and how the 240 is made from the 3 wire.

Personally I would simply change the breakers, identify the outlets as 240v and take the risk.

What could go wrong ?

he was an idiot. 240 volts is 240 volts. It is often delivered as 3 phased power, but that is irrelevant for the device - basically 3 phase power allows you to transport more load with the same amps, but the phases get split. In my appartement for example we have one phase for the kitchen heavy users, one for the light, one used for the room outlets - with the electricity soon also powering a separate server circuit. 3 phase in, 3x1 phase out. Every device jsut gets one phase, except SOME that are very heavy load and require special cabling (some heave ovens for example take 2-3 phases).

Thanks, that make sense.

Anyone here moved to 240v for that 3% efficiency ?

No. Most countries ARE on 240 volts ;) Never seen 120 volts outside the US (note: I was not everywhere on this planet).

U.S. and Canada. and from Mexico to much of Brazil all are.
 -  http://www.kropla.com/electric2.htm

Well, there still is 50Hz and 60Hz...  :-[

I would suggest you change the outlets to Schuko or, well, any that are used in 220-240V countries, then you will be less likely to plug a 120V device to 240V outlet.

Anyway, I read somewhere that 240V in US is made from two 120V live wires 180 degree out of phase. I do not know if that's true or not (I live in Europe so I have no way to check), but in Europe 230V (it can be 220-240 depending on the country) is single phase (meaning you get one live wire and one neutral). I also do not know what the effects of split phase 240V would be on the devices (maybe none).

Also, the frequency in Europe is 50Hz, so, for example, a synchronous motor will spin faster in the US.

Anyway, I read somewhere that 240V in US is made from two 120V live wires 180 degree out of phase. I do not know if that's true or not (I live in Europe so I have no way to check), but in Europe 230V (it can be 220-240 depending on the country) is single phase (meaning you get one live wire and one neutral). I also do not know what the effects of split phase 240V would be on the devices (maybe none).


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It appears the same to the device. 

I am using 240V 60hz with my computers with no issues...the main benefit is that you have 1/2 the line current so there is less line loss and you can run more rigs with an even balanced load as opposed to "wall socket" 120v

One PC per 15amp breaker is a real pain to manage...

That's the main benefits I'm looking for.

I run all my mining rigs on 240v, because I live in an apartment and the wiring in the building just wasn't designed for the load I'm putting on it.

The outlet for my electric stove is 40 amp at 240v, so I made an adapter so I could plug a 240v extension cable into that outlet and still use the stove.

The cable I selected has three NEMA 6-15 outlets on one end, and one NEMA 6-15 male plug on the other.

I found NEMA 6-15 to C-13 (the typical PSU main power socket) and run with those, so it isn't possible to accidentally plug a 120v device into the 240v outlets.

My PSU's auto-switch from 120v to 240v, and do run slightly more efficient on 240v.\

The PSU's are all Corsair AX1200's,

The cables I got from a hydroponics shop...
http://www.horticulturesource.com/hydrofarm-240-volt-8-ballast-power-cord-p6174/?osCsid=b5157fd1e79ac4643f7262b66b7ba6cc
http://www.horticulturesource.com/hydrofarm-240v-extension-cord-with-3-outlets-25-ft--p9355/?osCsid=b5157fd1e79ac4643f7262b66b7ba6cc

What's your take on this ? 
I'd expect a 200$ 80+Gold PSU to handle almost anything ...

It appears the same to the device. 

I am using 240V 60hz with my computers with no issues...the main benefit is that you have 1/2 the line current so there is less line loss and you can run more rigs with an even balanced load as opposed to "wall socket" 120v
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Actually in the us 120 is made by seperating the two live lines from 240 all your power is delivered residentally as 240 pole to house

I don't think the US 240V is actually 2-phase. It has 2 x 180deg. out-of-phase components, one on each of the outer lines with the middle line being neutral between them. So connecting to each half of the 120V circuit is out of phase but the 240 is still single phase.

It would be easier with a diagram...

1 2 3
( | )
) | (
( | ) etc.
240 between 1-3 is single phase
but 120 between 1-2 and 2-3 are out of phase.

I'm not an power company technician so I'm not 100% certain of this but I have had to do some wiring in the past and this is what I recall of the setup.

I'm lucky as here in Thailand it's 240V and they use US style plugs too!!! Fortunately we don't have 120V appliances laying around or we'd burn them out often by accident.

About 5 years ago I bought a PSU that had not been set by the store to be 240V and I didn't check myself. When I plugged it in there was a big flash and bang! But the store did replace it for me as they are supposed to set the switch when they import these things.

I wonder on what appliances it does not work. (as they say)  Only problem I could see is with the 50hz vs 60hz.

I have faith that 240 is 240 and that my PSU doesn't care if it's 50 or 60hz

I just found this forum thread where some electricians (retired and not) explain how the US system works and that it is single phase. It appears to validate my little diagram above.

http://www.diychatroom.com/f18/can-someone-please-explain-us-240v-system-1-2-phases-13189/

quoting one post:

"So our systems for single family dwellings are actually 120/240 volt single phase 3 wire sometimes called the edison system."

That thread has nice diagrams and some good background info too. Worth reading. He explains that most non-electricians get mixed up about what phase means and use the wrong terms.

A 60Hz clock will run 5/6 as fast on 50Hz (including most digital clocks). Electric motors will run slowly which may cause an issue (for example AC or freezer.)

Most computer PSUs are designed for international operation, so from 100V/50Hz to 250V/60Hz.

Oops already covered.  Ignore!

Frequency doesn't matter at all for PSUs, most if not all will run on anything from DC to 100+Hz, since one of the first things that happens to the power once it enters the PSU is that it is rectified to DC. The 120/240 switch enables or disables a voltage doubler circuit, when it is set to 120, the voltage doubler circuit is switched in to produce 240VDC which is then down regulated to the output voltages. When its set to 240, the input is rectified to DC and regulated to the output voltage.

An interesting note is that if you want to run on DC, you must set it to 240V and feed it ~180VDC or above, the voltage doubler circuit will not pass DC.

The above is a bit oversimplified now that I think about it, forgot about converting RMS and peak voltages...

tl;dr because of this

By pulling over the amount of voltage (or amperage) off a wire than is recommended, you risk a burnout or fire.

/thread (unless I'm wrong)

Here you go.

http://www.powerstream.com/Wire_Size.htm

Here in my town (Blumenau, in Brazil), our voltage is 220v, delivered just two wires (phase and neutral). But we have the option to request a tri-phase power (330V), making the energy more efficient (be my next upgrade).

 ;)

Well I was wrong, then, as it seems a quick looks shows it being based solely on amps

Yep...until you reach the breakdown voltage of the insulator that is.

Good point, but as I see that as being an unlikely factor in a modern dwelling or building. But that is just my speculation

Typically 600V in US residential wiring.