Can anybody tell me if 3 computers are too much for a 20 amp circuit? Actually it is 3 monitors a printer "not laser" and 3 thin clients if anybody knows what a thin client is. it is about the size of a book and is not a full tower so I assume it consumes alot less power then a full computer tower.
True thin client workstations are far less power hungry than their larger PC cousins. Also, keep in mind that even though a desktop PC may have a 400-watt power supply, its maximum power draw is likely to be less than half that.
Here's the scoop according to eWeek:
"While a PC can consume as much as 220 watts of power, a thin client such as Sun's Sun Ray 2FS consumes less than 8 watts. Even a thin client with a processor and DDR (double data rate) RAM such as HP's HP Compaq t5720 consumes about 30 watts or less."
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If the accompanying monitors are LCD flat screens, add an additional
30 to 60-watts per workstation; if, however, they are of the CRT variety, you might bump that number up to 100 or 120-watts.
One other thing to note: if these thin clients are, in fact, older generation or "obsolete" PCs that have been "reborn" as thin clients,
150-watts per workstation may be a more reasonable estimate.
So with that in mind, total wattage could fall anywhere from as little as 150 to 200-watts (< 2.0 amps) at the low end, to perhaps as high as
800 or 900-watts (< 8.0 amps), with the monitor type accounting for much of this spread. Even at 900-watts, this load would represent less than half the circuit's rated capacity; a 20-amp circuit would seem more than sufficient.
Well personally I would go by the wattage of the power supply, not what a magazine article tells me, but I don't manage thin clients in my data center.
I suspose you're probably more realistic here. If it were me I'd break it out into at least 2 15 Amp circuits - not knowing anything at all about his situation other than what little was provided. At least then you could comfortably put something else on the circuit - like lights, a small fridge, network routers, fans for the room, a radio, creature comforts.
According to the EPA, a typical desktop computer uses between 25 and
60-watts and a CRT monitor between 55 and 90-watts (they peg LCD monitors at 30-watts). At the upper end, that suggests the combined wattage of a computer and monitor would be in the order of 150-watts.
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According to an article published in this week's Economist, "a typical desktop and monitor together use perhaps 150 watts."
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Tufts University tells us "the average desktop computer uses about 120 Watts (the monitor uses 75 Watts, and the CPU uses 45 Watts.)"
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A 20-inch iMac "with both of Core Duo's cores cranked to 100 percent utilization," is reported to consume just 95-watts.
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So, if you wanted to be a bit more cautious, you might budget a combined total of 200-watts per workstation. Again, we're told these are thin clients and not high-end servers, so you wouldn't expect them to be decked out with multiple hard drives nor power guzzling multi-chip processors.
I'm sure some of the larger CRTs could consume in excess of 100-watts but more typical office-type CRTs are likely to come in below this. For example, the University of Waterloo tells us their 17" SONY CRTs draw 75-watts when in use.
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The maximum power draw of my 17" NEC MultiSync LCD 1700V (the one I'm using now to type this) is 40-watts and in standby mode it comes in at under 4-watts.
Unless we're looking at some unusual setup, budgeting 30 to 60-watts for a 17 to 19-inch LCD panel and 75 to 125-watts for the equivalent CRT doesn't strike me as unreasonable.
As a sidebar to this, with the low cost of LCD panels, I can't imagine why anyone would want to buy a CRT monitor, unless they had a pretty compelling reason to do so. I can purchase a name brand 22-inch LCD monitor for under $400.00 Canadian (less than $340 US) and a 17-inch LCD monitor for half that. The energy savings and, in particular, the resulting space savings make this a no-brainer.
The other thing we shouldn't forget is that OP has told us these are thin clients about the size of a large book, so it's safe to assume their power consumption is quite low. We know, in fact, the Compaq t5720 has a maximum power draw of just 30-watts and that Sun's Sun Ray thin client is under 8-watts, or about the same amount of power as would be consumed by a night light.
So if we were to allocate 60-watts for an LCD monitor and 40-watts for a thin client PC, our total combined wattage for these three work stations is 300-watts (~ 2.5 amps) and that's being rather generous. And if CRT monitors are used in lieu of LCD panels, total wattage might then jump to between 350 and 450-watts (< 4 amps).
Simplest way to find out without guesstimating is to use a Kill-S- Watt, and _measure_ the actual va, watts, amps, whatever drawn by the combination of devices connected downstream from it. Clue: watts are not the limiting factor, since power-factor can vary widely; count amps.
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