Amperage pull of a computer?

I am wondering if anyone knows the approximate amperage use by a typical home desktop computer and monitor, or if there is an easy way for me to determine this on my own. (in U.S. with 120 V circuit).

I have other devices that I'd like to know also, such as electronic music synthesizers and an audio mixer. I ask because I live in a very old building with weak circuits, and I want to know how much I'm pulling when I turn different combinations of devices on.

Thank you.

Jaxon

Reply to
Jaxon Bridge
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I think the easy way is called "the data plate on the back."

They also have them.

If you want something more accurate, you'd probably need to buy a wattmeter.

Reply to
Charles Perrin

On Sun, 25 Jan 2004 21:45:01 GMT, Charles Perrin Gave us:

Uhhh... The "data plate on the back" is ONLY a declaration of what the power supply is capable of producing, NOT what the device the power supply powers (the PC) uses.

Monolithic devices typically state what they actually do use. PC power supplies state what they CAN use as a maximum. That figure is rarely what they actually do use.

Reply to
DarkMatter

There is no such plate on the back of my computer. However, there is a sticker on my synthesizer that says 25 watts. Does anyone know the approximation of a computers wattage/amperage?

Thank you.

Jaxon

Reply to
Jaxon Bridge

You would do good to believe your synth's sticker, at least on a basic level. OTOH, computers aren't so well behaved. The manufacturer has no clue what widgets you've added to your system, so the label is more-or-less a worst case. It's typically far less than this.

The next question is whether you're worried about the current drawn ("amperage") or the power consumed. The former (VA) is important if you're interested in a backup unit. The latter is important if you're worried about power consumption (cost of electricity) or heat output (thus cooling requirements).

Reply to
Keith R. Williams

On Sun, 25 Jan 2004 20:50:50 -0500, Jaxon Bridge Gave us:

Said "plate" is actually a sticker, and it can be found on the power supply in the PC. That might require removing it to read it.

In any case, the computer will NOT be using what the supply is rated at producing.

Nearly ALL power supplies are like this. They get rated on their capability, not their consumption.

Most any stand lone device or dedicated power modules get rated on what they consume under normal use at nominal line voltage.

Reply to
DarkMatter

Read the wattage on the monitor and get the amp clamp out and measure the computer current when it is not in power saving mode.....then we do our arithmetic.....It's not rocket surgery now is it!......

Reply to
Ross Mac

My 1KVA UPS has my entire office connected to it comprised of the following:

520W P.S. in the computer HP Photosmart Printer HP Scanner 4 wireless USB ported devices my phone and answering machine HP Fax/Copier 2 high quality halo lamps a nice 200W sound system (auxilary input is from the computer) Cross Cut Paper Shredder a clock

Since you asked, I turned everything on at once and put a Fluke Amp Clamp on the power cord to the UPS which is on a 20A breaker. Reading with everything fully on performing tasks is 11.85A. With most peripherals in standby but normal use of the computer..... 3.8A. The paper shredder by itself uses 3.65A according to the amp clamp.

Reply to
EEng

For Gods sake buy an amp meter and/or watt metter and find out for yourself!

Reply to
Brian
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Isn't volt-amps (or more properly, the amps portion) needed for calculating the circuit capacity? In other words, with a 100% power factor you could pull 1,800 watts on a 15 amp circuit, but with a misearble power factor of 50% (chosen just to make the math easy) you're limited to a mere 900 watts?

(and, of course, an additional 20% derating for continuous duty)

if you've got a misearble power factor of 50% then you better not pull more than

Reply to
danny burstein

On Mon, 26 Jan 2004 03:38:50 GMT, "Ross Mac" Gave us:

For a monitor, merely read its published spec sheet, or the power consumption declaration on the rear of the device near the line entry module.. They are typically accurate. A monitor is a stand alone device, and is declared as stated above.

AC inductive current probes aren't cheap. Nice try though.

Open the AC line in the power strip, and install a 0.1 Ohm precision resistor in series with one phase, and read AC volts in RMS directly across the resistor and convert to current. Real simple. Be sure to keep the probes isolated from everything. The meter and probes "float high" as well, if one is on the "hot" side. I would suggest the neutral line.

Reply to
DarkMatter

On Sun, 25 Jan 2004 19:47:08 -0800, EEng Gave us:

The 520 Watt PC supply does NOT use 520 watts, UNLESS your PC is filled chuck full of peripherals, and high current hard drives. Very unlikely, even then.

The halo lamps use exactly what they state.

The 200W audio "system" does NOT use 200 Watts, until and unless it is fully cranked up with signals being fed. At that point, it PUTS OUT 200 Watts over the channels included, but would also consume MORE than 200W to make it there at the outputs. Sitting at idle, I'd say it uses less than 100W, and that still until you get up over 2 Watts per channel, which, believe it or not, is fairly loud. I have never cranked up my Monsoon flat panel 6 ch system past few watts. I have neighbors around me.

Why you hang non-essential appliances like a shredder and "halo" lamps on a UPS is beyond the grasp of ny logical man. In a power outage, they could easily be added, if one really needed to operate them in such circumstances. Did you break the line cord open, and place the meter on one line only?

Reply to
DarkMatter

I never stated that anything used any specific amount of current. I never stated that anything runs at any particular rate. I merely hooked up my entire office to my UPS so I could use an Industrial Amp Clamp to easily take an accurate measurement. My very point being that in general, an entire office doesn't use even 15A.

Reply to
EEng

On Mon, 26 Jan 2004 01:32:40 -0800, EEng Gave us:

I never said you did. I was merely stating what they didn't use, in a couple of cases.

I didn't say that you made any incorrect statements, I merely clarified what others might read your data as being a declaration of.

Ahhh... They tend not to read low AC current very well. I see.

Hehehe.. Let's hope not. I burn one 15 watt fluoro bulb and three PCs 24/7, and they don't use much. The bulb and monitors are off when not used. The PCs crunch seti units all day. My dual CPU box does more than twice what the others do. They burn the same power whether idle, or doing full crunches... bits are bits... I had some dude arguing with me that a PC doing some problem (like say fractal generation) uses more wattage than an idle PC.

I told him he was nuts. Idle PCs still have instructions flowing in them, and the average number of high bits is usually always around

50%, so they do not consume more. A PC doing peripheral services might, however.
Reply to
DarkMatter

message

I suppose if accuracy at that level is important, the series resistor would certainly do the trick. I think the OP said "approximate"...In that case the amp clamp or even a DMM should suffice...

Reply to
Ross Mac

Wrong!

You're the one who's nuts, DimBulb (nothing new here). All modern processors (x86 anyway) have a "Halt" instruction and all OSs after Win95 make use of it (and Win95 can with an add-on). When in the OS's idle loop the CPU is halted and no instructions are executed. Newer processors also shut down units that aren't being used. For instance, if there are no FP instructions in the pipeline, the FPU's clocks are stopped. The power output of a modern processor certainly *does* change with varying workload! It'll change by an order of magnitude or more (though advanced processes aren't making this easy).

Reply to
Keith R. Williams

On Mon, 26 Jan 2004 12:25:46 GMT, "Ross Mac" Gave us:

How would a mere DMM suffice? If you are going to break the line to place the meter inline with the load to use the ammeter section of the DMM, you are adding the meter lead drops in as well. Bad Idea. The resistor shunt I described is the best, most accurate, and least expensive method. It can also be installed permanently, and forgotten about until needed.

Even the single piece price for one is negligible. And simple volt readings and a conversion is all that is needed to get the result.

The drop on the meter leads would certainly change the voltage at the outlets supplying the device in question. The resistor, near nil.

The current meter section of a DMM is not very good for higher currents as it actually changes the circuit with the Vdrop on the leads, and gains an inaccuracy for the same reason. The voltage present at the device under test differs by a greater margin as well. There is also a slight chance of heating the leads as they are typically only like 22Ga or higher. Not good for much more than an amp or two.

Reply to
DarkMatter

You should have listened to him as they do, plain and simple. If you don't believe me, just run some CPU temp monitor software and notice the temp drop when you stop SETI crunching. A fairly idle pc (using a real OS) will do CPU Halt calls instead of running an idle loop. This results in less power being dissipated and consequently lower temps.

Reply to
Anthony Fremont

Reply to
Jaxon Bridge

Then use the clamp....my meter is a Fluke 8062A and is quite accurate...but like I said, your method is the most accurate....The OP was just looking for an approximation...

Reply to
Ross Mac

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