Simple question: Most power supplies are auto-sensing between 110V/120V and 220V/240V. This begs the question, can they use 240V in North America i.e. connected to both hots (red and black)?
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3 Answers
Most PSU support wide range input from 90 to 260V.
If you have a 3-phase line, then the voltage between 2 phases is 110*√3, not 110*2.
Check the spec of your PSU. If unsure, you should avoid it. If you like fun, just try it out, but be prepared to dial 112 (Germany, Europe), or 911 (US).
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Does the PSU support an input that is changing in voltage during operation, i.e. voltage fluctuations within that range of 90 to 260V while it's running?– davidtgqCommented Dec 31, 2015 at 9:20
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Don't know if fluctuations over the whole range are supported, but I think so. Read the spec of your PSU to find out if it supports wide range input at all. Commented Dec 31, 2015 at 10:21
In the US, 220V household wiring is single phase. The full 220V is used for heavy appliances, like electric stoves. The two legs are split inside the breaker box, and the separate legs are used for 110V outlets.
However, 220V outlets accept a different shaped plug, so you can't accidentally plug a 110V appliance into 220V and burn your house down. If the power supply was sold for the US market, it will have a 110V plug on the cord. If the power supply was sold for an area where 220V is standard, it will have a different plug than a US 220V outlet, so you wouldn't be able to simply unplug your electric clothes drier and plug in your non-US computer.
Which is why the power supplies are auto-sensing or switchable, and you can use the available local power without having to rewire your house in violation of building safety codes. But if you did have some kind of adapter to plug a non-US 220V power supply into a US 220V outlet, it should theoretically work.
answered Dec 30, 2015 at 15:43
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Now, I've never hooked my mains up to an oscilloscope before, but I was fairly sure that 220V in US was provided as two 110V lines that are 180 degrees out of phase. Each is a single phase, meaning that when they are tied together, they can provide 220V power to a device. This is why most 220V plugs have 2 hot wires and one neutral (no dedicated ground) in the US. Figures 1 and 2 here support this assumption: en.wikipedia.org/wiki/Split-phase_electric_power I do understand this is more semantics, as everything else you have to say is correct (AFAIK), but just though I'd chime in.– MagnaVisCommented Feb 7, 2016 at 1:57
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@MagnaVis: We're talking about the same thing. It's also referred to as split-phase. There's nothing mutually exclusive in what we're describing, just another way to express it. Commented Feb 7, 2016 at 2:28
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Thanks! I thought maybe we were talking about the same thing because you did refer to them as "legs", as I would (implying they are actually out of phase with one another). The one thing that threw me was the reference to single phase.– MagnaVisCommented Feb 7, 2016 at 2:35
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@MagnaVis: the 220V is one phase of the 3-phase generated power, which is split into two 110V halves. The halves add to 220V because, by definition, they're 180 degrees apart (think of the center as zero, with +110 on one side and -110 on the other; there's 220 between them). Commented Feb 7, 2016 at 3:09
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That's a great way to think of it, thanks! I also found this, which goes into more detail: ctgclean.com/tech-blog/2015/08/electricity-behind-walls Interesting stuff!!– MagnaVisCommented Feb 7, 2016 at 8:38
It should be fine. Many countries have unpolarised plugs and sockets so there is no real distinction between hot and neutral in appliances designed for the worldwide market.
Obviously you would have to buy or make a suitable power cord and be careful what you plug said power cord into.
http://www.stayonline.com/208v-straight-blade-cords.aspx
I would also make sure you use reasonable overcurrent protection. Don't go connecting a computer directly to a 50A or so cooker circuit.
