Running PC on 240V 60Hz

I've scrounged around looking for a UPS (of the double conversion online type where AC is continuously converted to DC and back to AC again) that
has 240 volts input, and 120 volts output. So far I have found nothing in the range I'm looking for (2400 watts) that doesn't boost the price by $1000 with a transformer on the output. I don't know if this is a market issue or if they are insisting on having units work in bypass mode (which would obviously not be an option for 240 to 120 without a transformer).
The reason I'm looking is that I have a situation where I need to run many computers in a room where I cannot add new wiring, but a 20 amp 240 volt outlet is available and live (formerly used for a window air condition I suspect, due to it's location about a foot to the left of under a window). 20 amps at 120 volts would not provide the capacity I need, but 20 amps at 240 volts I believe will.
So plan B:
Get a 240 to 240 volt UPS. Run as many PCs that can on 240 volts. All but one have the little red switch in the back, usually labeled 115/230. It seems from some research that the same power supplies models are sold in all countries from Japan (100 volts) to Australia/UK (240 volts) and at both 50 and 60 Hz. PDUs for 240 volts might be the next problem, but I have seen IEC PDUs and I can use IEC-to-IEC cords.
Other stuff (monitor, wall warts for switch, modems) would then be run on the regular 120 volt circuit there in the room.
The question:
Have any of you who are in the USA operated PCs on 240 volt 60 Hertz power? Are there any disadvantages to operating them this way? Are there any known issues with them being powered by a circuit where both wires are 120 volts relative to ground (e.g. neither is a grounded conductor)?
I want to avoid the added expense of a transformer.
One of my PCs (I forgot where I got the case for this one ... I built them all myself) has no voltage switch. Any chance it is an autoranging model? I guess I should play it safe and leave that one on the 120 volt circuit.
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snipped-for-privacy@ipal.net wrote:

Actually, the power supplies will operate at slightly greater efficiency when run from 240V. (Only ~1%)
The only problem might be in getting the 20A branch circuits to the PC's the standard line cords supplied with PC's in the US fit 120V sockets with a ground pin and have parallel prongs for "hot" and neutral. The 240V sockets fit the same outlet boxes, but have "tandem" prongs. I haven't checked for the availability of PC line cords to this configuration, but they may be available. Otherwise it's simple to replace the present 120V plugs. (Any ham could do it.) :-)

I'd check the specs or have a look inside. I've never seen a 120V only ATX power supply. It has to have the doubler circuit to work on 120V, and to change to 240V requires only a SPST switch.
Virg Wall, K6EVE

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Is it three prong 240 volts or four prong. Makes a significant difference to the computer.
snipped-for-privacy@ipal.net wrote:

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Why, the PC is a line to line load. It should work fine on 240v if the PS has the 240v switch (some even autoswitch) Ground is still ground Tom's usual "fix your ground electrode system and install real surge protection" still applies) When you extend this 240v line, bond the ground from the box to your 120v boxes. You will need NEMA 6-15 cord sets but they should be pretty common in the used market from old computer equipment.
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| Is it three prong 240 volts or four prong. Makes a | significant difference to the computer.
It's definitely a NEMA 6-20R. It looks like this, although it's really in a ROUND hole, not a square one (I'm not good at doing round in ASCII.
+---------+ | * | | | | -- |- | | | +---------+
Display in a fixed space font like courier if it shows bad.
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snipped-for-privacy@ipal.net wrote:

The computer could care less, if it gets 240 volts across the PS input and has its case grounded properly. Conforming to electrical code is another thing entirely!

A solution which would probably meet code would be to attach a standard dual duplex box to the existing 240V outlet box, ensuring that the two metal boxes are electrically connected. Then use two 240V, (tandem blade), duplex outlets in the new box. You would need extension cords to the individual computers. A second box could be attached, giving an additional four outlets. Your local code may not allow additional outlets on 240V circuits, but at least this meet safety standards.
Using the existing 120V, (parallel blade, U ground) at 240V will work electrically, but is definitely not in accordance with code, otherwise you could just build a junction box with 120V duplex sockets and wire it to the present 240V outlet with a cord with the correct plug for the existing outlet. I *DO NOT* recommend this!
In any case make sure the existing ground in the present circuit is preserved. This will be a green or bare wire, or in many cases, the metal box and the flex or EMT feeding it will be the ground. This must be electrically connected to the ground pin in all sockets.
Virg Wall, P.E.
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| snipped-for-privacy@ipal.net wrote:
|> | Is it three prong 240 volts or four prong. Makes a |> | significant difference to the computer. | | The computer could care less, if it gets 240 volts across the PS input | and has its case grounded properly. Conforming to electrical code is | another thing entirely!
I just wanted to make sure it didn't assume a grounding polarity since both 120 volt countries and 220-240 volt countries supply their standard voltage as hot+neutral.
|> It's definitely a NEMA 6-20R. It looks like this, although |> it's really in a ROUND hole, not a square one (I'm not good |> at doing round in ASCII. |> |> +---------+ |> | * | |> | | |> | -- |- | |> | | |> +---------+ |> |> Display in a fixed space font like courier if it shows bad. | | A solution which would probably meet code would be to attach a standard | dual duplex box to the existing 240V outlet box, ensuring that the two | metal boxes are electrically connected. Then use two 240V, (tandem | blade), duplex outlets in the new box. You would need extension cords | to the individual computers. A second box could be attached, giving an | additional four outlets. Your local code may not allow additional | outlets on 240V circuits, but at least this meet safety standards.
Where does the UPS fit into that?
| Using the existing 120V, (parallel blade, U ground) at 240V will work | electrically, but is definitely not in accordance with code, otherwise | you could just build a junction box with 120V duplex sockets and wire it | to the present 240V outlet with a cord with the correct plug for the | existing outlet. I *DO NOT* recommend this!
I have no intention of using NEMA 5-XX at anything more than 140 volts.
| In any case make sure the existing ground in the present circuit is | preserved. This will be a green or bare wire, or in many cases, the | metal box and the flex or EMT feeding it will be the ground. This must | be electrically connected to the ground pin in all sockets.
If I can find smaller 240 volt UPSes, I might go with two of them. But I have found a 240-in 240-out at the size that would let me use the full capacity of the 20 amp 240 volt circuit. I can _build_ a 240 volt PDU if I need to. I already have half the parts for that, now. Cord that have IEC-320 female and NEMA 6-15P male would be cool. I found ONE at a shopping site, but it's a $20 thingy from Cisco. I'll decide later if I waste money on that or just cut plugs off the excess 5-15P cords I do have and stick hardware store 6-15P's on there. Premise wiring will be to code, and the PDU will at least be right, if not UL-listed.
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snipped-for-privacy@ipal.net schrieb:

Hello,
the plugs used in germany (Schuko) may be inserted in two positions, this will swap hot and neutral. The computer therefore should not expect the hot line to be really the hot one. Computers build for export to Germany too should not assume a grounding polarity. But you should check that with your computers.
Bye
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wrote:
| snipped-for-privacy@ipal.net schrieb: |> |> I just wanted to make sure it didn't assume a grounding polarity since |> both 120 volt countries and 220-240 volt countries supply their standard |> voltage as hot+neutral. | | Hello, | | the plugs used in germany (Schuko) may be inserted in two positions, | this will swap hot and neutral. The computer therefore should not expect | the hot line to be really the hot one. Computers build for export to | Germany too should not assume a grounding polarity. But you should check | that with your computers.
So how would you ensure that the metal base of a screw in light bulb has the grounded, rather than the hot, wire connecting to it? Or is that just not done in Germany?
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snipped-for-privacy@ipal.net writes:

I suspect the Germans are smart enough to know 'don't put your fingers in light bulb sockets', unlike too many Americans. :-)
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Michael Moroney wrote:

Also note that most American table lamps come with cords having non-polarized plugs. :-( But then, it's only half the voltage! :-)
Virg Wall
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Michael Moroney schrieb:

Hello,
the safety regulations for electrical equipment used in Germany do not assume smart enough users. ;-)
Bye
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wrote: | | | Michael Moroney schrieb: |> |> I suspect the Germans are smart enough to know 'don't put your fingers in |> light bulb sockets', unlike too many Americans. :-)
| the safety regulations for electrical equipment used in Germany do not | assume smart enough users. ;-)
So you have light bulb sockets that fingers cannot get into?
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snipped-for-privacy@ipal.net schrieb:

Hello,
we have the small ones but also those big enough for fingers, but the finger must be fully inserted before a dangerous contact is possible.
Bye
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snipped-for-privacy@ipal.net schrieb:

Hello,
if it is a lamp connected with a Schucko plug, the screw could be connected to the hot wire. But we have special lamp sockets here with two contacts at the base and the screw of the socket is isolated from these contacts. When you touch only the screw of the socket with no bulb in it, you have no connection to the hot wire. If a bulb is screwed into the socket, the screw could be hot if the plug is inserted in one of the two possible positions. But it not possible to touch the screw when a bulb is in the socket.
Light bulbs on the ceiling should be connected with the hot wire to the central contact of the bulb socket.
Bye
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This applies in much of Europe. The French/Belgium plugs are not reversible in their sockets, but it is undefined which way round live and neutral are. Actually, in all double outlets and 2-way adaptors I've come across, the two outlets are internally hard-wired the opposite way round from each other, so it's not like there's even hint of a convention one way or the other.
In the UK, live and neutral are distinguished all the way into the appliance. Ironically, we use relatively few screw in light bulbs compared with rest of Europe (we're mostly bayonet cap B22d), but we do require the live/hot is connected to the centre/tip and neutral to the screw in the case of any screw lamp holders.
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Andrew Gabriel

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Probably better if he makes his own 'extension cord/power strip', so that only one 'device' (it) is plugged into the outlet, and there is absolutely no modification to the house. A 6-20P cord feeding a metal dual duplex box with 2 duplex 6-20R or 6-15R outlets. Maybe a second segment of wire from this box to a similar second box. (in our computer room we have daisy chains of 3 or 4 of these boxes with each box containing 2 duplex 120V outlets and a 3 phase 20A plug feeding it)
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Michael Moroney wrote:

I'd forgotten about the 240V ups! :-(

the UPS. The output of the UPS to

Good idea!
Virg Wall
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Phil, no computer shop that i have ever seen in the US has 220 (240) available on the test bench. consiquently you are setting the client up for some long term headaches. when the box comes back from service with the switch on 120 and gets pluged in to 240 ...
did you try Powerware?
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| Phil, no computer shop that i have ever seen in the US has 220 (240) | available on the test bench. consiquently you are setting the client up for | some long term headaches. when the box comes back from service with the | switch on 120 and gets pluged in to 240 ...
Don't worry. These are MY OWN computers. And except for a couple of old Sun Sparc machines, I built them all. The location is an upper floor of a house I am considering renting to live and work in. The lady who owns it doesn't want any construction work done on it to add another outlet. Fortunately, it now has central A/C. I just hope it will be enough for the heat I'll be releasing. I have 6 computers now, and will be adding 4 more. I could run a couple in another room but the rest need to be together.
| did you try Powerware?
Yes, that was one of them. Also tried APC, Tripp-Lite, Sola, and a few others I've forgotten.
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