How much Voltage Drop is acceptable for computers? Outdoor Desktop Office

You need a licensed electrician for this.

Voltage drop should not be a problem, but this is the kind of high voltage project that I would leave to a professional.

BUT, most computer and monitor power supplies are not PFC, not power-factor corrected, and draw their current in a short pulse in the middle of the sine wave. With a stiff source impedance they draw about 10x the rms current, so that'd be 20A and a 16V drop. Of course we'd not call 0.8 ohms a stiff source, so the pulse wold be spread out some and the drop a bit less severe.

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The computer power supply, as well as the monitor, should have a label that lists the acceptable minimum for the applied voltage.

The equipment you list seems like a fairly light load however, use should uses large gauge wire for long runs. You can also use a double run of smaller gauge wire. Further, insure you use cable rated for direct burial or use electrical conduit. If you opt for conduit, slope it and provide a sump.

Will you be adding a breaker to your service panel to supply this line?

First you need to know (measure) the total current drawn by all of the loads. 10 AWG wire is about 1 ohm per 1000 feet and 12 AWG wire ia about 1.6 ohms per 1000 feet. For a 250 foot run, that is a total of 500 feet. Say you used 12 AWG, that would be about 0.8 ohms; at 2 amps current (crudely 250 watts) that would give a drop about 1.6 volts - which is not enough to worry about. You should use wire rated for underground useage, and have zero splices anywhere outside (or underground). Do not buy used wire, the cost savings is not important; *safety* IS important and well worth a few dollars.

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Computer power supplies are often rated for 90 to 132V and usually exactly twice that with switch in 230V position. Many monitors are rated for full range 90 to 264V. Use a good power supply though. Cheap power supplies often have a narrower tolerance and when you go out of the band, your PC will crash or reboot. Because of the way computer draws current, power factor is about 0.6. Because it's crest factor is so high, peak current can be over 3 to 1. Thin wiring will result in high harmonic distortions at the line end making the top and bottom of sinewave closer to a shape of mesa.

Considerably less severe. I don't have data for 120 V mains, but this issue is important for IEC 61000-3-2 and -3, and 0.8 ohms strongly tends to turn 'rapacious' rectifier loads into pussy-cats.

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"Stiff source impedance"? I know what you mean, but have never encountered that curious term before...

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"What is now proved was once only imagin'd." - William Blake, 1793.

You did not mention where you are from. Here in the US, as a general rule of thumb if you go with a run larger than 50' you should use the next wire size. A run of 200 - 250' I would go with a "Sub Panel". A 40A Sub Panel, with 20A circuits should fit your needs.Check with your local codes and the NEC code book, or better yet confer with a licensed electrician if you've never done this work.

Not sure where the OP is but assuming he has a 110VAC supply, even with 10 gauge cable, at 250 feet length and assuming a 500W load (which seems about right for what he's saying), there'll be of the order of 10 volts drop along the cable. It doesn't sound much but that also means that there'll be about

1W per foot of cable being dissipated 'somewhere': this is a recipe for disaster.

That length of extension is a job for someone who knows their stuff and can do it properly - they will probably even be able to source the cable cheaper than the lay person.

Ken

Art of Electronics.

I don't think so... "stiff signal source" might be a better term.

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"What is now proved was once only imagin'd." - William Blake, 1793.

Really? That sounds a lot less costly. Is there a way to have a double run result in one outlet, or do you just have two?

Thanks Dub

Run 240 with a neutral, and split the load at the shed.

Cheers! Rich

I'm sorry, I don't understand what you mean. I'm a total newb at electricity, sorry.

That's why I recommended a licensed electrician. It may be required by law in your area that you use a licensed electrician. It's not excessively expensive, and the house you keep from burning down will be your own.

According to your original post,

Well, first, you should use a real electrician, especially if you didn't understand my comment.

If you simply use an extension cord to go 250 feet, you'd need about #8 to really supply the whole room on 120V. One thing that will halve the size of wire you need, but increase the number of conductors by 50%, would be to wire a 240V three-wire subcircuit, that's black and red, the two opposite legs of the 240, and white, the neutral. In normal 3-wire wiring, the black is 120V relative to neutral, and the red is also 120V, but with opposite polarity (so from black to red is 240, but you don't need to worry about that) When you get into the shed, split the neutral to go along two buses - black/white and red/white. Plug half of the stuff into each.

Hope This Helps! Rich

such that black is 120V to