I'm finishing all the modifications to Knight's Rest's PSU, and I wondered if the change to 220V would be worth it? The PSU states that it's 1100W with 110 and 1450w with 220, and I know you can pick up some efficiency as well. This is a Delta PSU, mind. Server equipment. If I'm not mistaken, they're made to run on 220, aren't they?
I thought voltage at the wall was 110V for you Americans and 230 over here. Most PSUs switch automatically. Its got a special name I can't remember.
I believe most new homes here in the US are wired for 240V, split into 120V on the hot and neutral. Standard wall outlets are typically wired for 120V (though the actual voltage range is typically 114-126V). My house was built in the mid-1980s, and every outlet I've measured has come in right at 120V. Most houses are wired with a couple of 240V outlets for large appliances such as clothes dryers, and if you're lucky you might get at least one 240V line in the garage just in case you have beefy power tools. Edit: As to whether or not it's worth running a new 240V (or 220V) line just for your computer, I suppose it's really a matter of personal opinion. I'd love to run one to my garage (see above), but time and resources have dictated other priorities.
I think it's part of the long and sordid history that goes back to the current wars with Westinghouse, Edison, and Tesla.
... You get a smaller shock if you cut something... For the same reason site tools in the UK are also 110V, but they're even safer as they're centre tapped (55/0/55, no earth, double insulated) for, let's say obvious reasons A disadvantage is that higher voltages (actually lower current, but hey) have lower transmission losses over distance, though at the local-sub-station to house end it's pretty negligible.
I wouldn't bother with the expense or the hassle of installing a 220V line just to eke a bit out of a PSU.
Uk mains is 230V hot to neutral, US is 240 hot to hot 180 degrees out of phase, which I'm not sure would work properly. I know I've seen data centers and Telco equipment running 208V and 240V, but I'm not sure consumer equipment can handle it. Anyone have an old power supply, a fire extinguisher and an appetite for destruction?
What play_boy is saying is that the phase difference of the US standard 240V compared to European 230V might be too much for the equipment; leaving you with a very expensive paperweight, or at worst, a fire.