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Cost to run conduit to shed

Icecold

Senior member
Nov 15, 2004
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I'm interested in running a bunch of conduit to shed on my property. Basically, the goal is to run ~4 circuits and network from my main breaker panel to a sub panel in a shed ~100 feet away. The goal would be to have ~10 3080 level graphics cards inside 10 3950x(or equivalent) PC's, and an appropriately sized window air conditioner running. This would be primarily for TeAm Anandtech distributed computing projects(think crypto coin mining, but for COVID fighting purposes and other science - see DC subforum for more info). I was wondering if anybody has any ideas on ballpark what I would be looking at in terms of cost? It will likely have to wait until the spring since I'm in Ohio so it will be too cold soon to trench conduit. I'm hoping I'm looking at < $20k for the electrical portion, but am calling for quotes on Monday and was hoping to have a general idea. I have tools/labor if doing the trench ahead of time is likely to save me on the total cost, but I wasn't sure if most electricians would be okay with that. I really appreciate the help!
 

sswingle

Diamond Member
Mar 2, 2000
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Not an electrician but a few thoughts based on what I do know.
I'm sure most electricians would appreciate the trench pre dug.
Conduit itself is cheap. Not sure what size they need but maybe $2/ft
I would guess they would run an 80 or 100 amp circuit to the sub panel, not 4 individual 20 amp circuits. This would probably be done with 4 gauge wire which looks to be $4/ft
 
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Icecold

Senior member
Nov 15, 2004
446
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Not an electrician but a few thoughts based on what I do know.
I'm sure most electricians would appreciate the trench pre dug.
Conduit itself is cheap. Not sure what size they need but maybe $2/ft
I would guess they would run an 80 or 100 amp circuit to the sub panel, not 4 individual 20 amp circuits. This would probably be done with 4 gauge wire which looks to be $4/ft
I appreciate the reply! Any idea if I could trench, run the cabling and conduit, etc. and then just pay them to hook it to the panel / add a panel, etc.? I can do the manual labor portion myself it it makes it cheaper.
 

herm0016

Diamond Member
Feb 26, 2005
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you should be able to do it yourself. as long as you keep the trench open for inspection. check your local code for depth. how many amps do you need? 4 regular circuits is only 60 amps if they are all at max current. if you have a 200 amp service, you can probably run 80 or 100 to the shed, but if you have 100 amp service, all you may be able to do is 50, depending on your mains capacity. a licensed electrician should be involved to decide the wire size and amp rating for the breakers.

i ran a 20 amp circuit to my sheds with direct bury cable over the summer.
 

Icecold

Senior member
Nov 15, 2004
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Distributing outhouse?
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Basically :) . Honestly I can't think of a better shed / outhouse. A bunch of PC's keeping it warm all winter - and it's helping fight COVID/cancer/etc. Maybe adding a nice(really private, it's in a shed :p ) bathroom makes sense :)
 

Icecold

Senior member
Nov 15, 2004
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You might as well go with 40 3080 tier cards. 4 for each 3950x. :p
I should be able to get 100 amp service to the shed. Doing the math.. maybe I suck at Ohms law and general math.. but that should be 12000 watts.. say 1500 watts for the 10 3950x's.. maybe less if I undervolt them.. I probably could run 3 cards per system with thee cards set to a reasonable voltage an and still have a small amount of room on the panel for an air conditioner? I wonder how much heat 30 RTX 3080's would put out.
 

Greenman

Lifer
Oct 15, 1999
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Here in CA I could do that job for you for around $7k. It should be a sub panel in the shed and distribute from there. Keep in mind that a detached building with a sub panel has to have it's own ground, separate from the house.
 

Greenman

Lifer
Oct 15, 1999
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I should be able to get 100 amp service to the shed. Doing the math.. maybe I suck at Ohms law and general math.. but that should be 12000 watts.. say 1500 watts for the 10 3950x's.. maybe less if I undervolt them.. I probably could run 3 cards per system with thee cards set to a reasonable voltage an and still have a small amount of room on the panel for an air conditioner? I wonder how much heat 30 RTX 3080's would put out.
Are you suggesting that those 10 cards draw 10 amps each?
 

Icecold

Senior member
Nov 15, 2004
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Are you suggesting that those 10 cards draw 10 amps each?
Each PC would draw around 1000 watts - a 16 core CPU at ~150 watts and 3 graphics cards at ~275w each. I would ideally have about 10 of these in the shed. I was just saying based on my current electric service I think I could get a 100 amp panel out at the shed.
 

herm0016

Diamond Member
Feb 26, 2005
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100 amps at 240 volts is 24000 amps. You will be running 240 to the panel. Half your load should be on each 120 volt hot leg.
 

Skillz

Member
Feb 14, 2014
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I don't think I would bother with an air conditioner. Assuming you don't live in the deep south somewhere I'd just leave a window open with a box fan blowing air in/out or cut a hole in the top of the wall to draw hot air out.
 

mindless1

Diamond Member
Aug 11, 2001
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^ Some areas of Ohio get past 95F peak in summer. It doesn't seem wise to risk thousands in equipment and electrical setup just to avoid an air conditioner in *most* cases, except that in this case, the load is not something a mere window unit A/C can handle, nor some consumer grade window box fan either.

I wonder how much heat 30 RTX 3080's would put out.
You estimated 1KW/system x 10 systems = 10KW. That all converts to heat.
34121 BTU/hr

If using a fan alone, I'd not run them open air in the shed, rather some kind of hood/duct arrangement to extract exhaust and expel from the shed instead of recirculating the heated air.

Depends on the shed design, how to best set that up.
 

Icecold

Senior member
Nov 15, 2004
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I really appreciate everybody's input! Maybe 5 systems with 3 cards each would be more reasonable. That would probably keep it at a point where a good size window air conditioner could properly cool it. It does get fairly warm where I'm at in the summer, but I ran some PC's in my non air conditioned garage and it seemed to run okay. Of course having a bunch in a closed shed is a totally different situation.
 

bbhaag

Diamond Member
Jul 2, 2011
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You either meant watts, or he's powering a flux capacitor.
Haha no doubt. Could you imagine the setup needed for 24,000 AMPS lol it would be insane.

Anyway, not sure if it's to code in your area OP but could you use direct burial cable to save few bucks versus running conduit?
 

mindless1

Diamond Member
Aug 11, 2001
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^ Heh, here we go again. There's a few people who argued against my acceptance of direct burial ethernet in a topic here, so surely they'll have a problem with direct burial mains.
 
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bbhaag

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Jul 2, 2011
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It was just a suggestion for the OP to consider not by any means a standard or ultimatum to the OP.
Ease of installation and a cheaper installation cost are two factors that I can think of off the top of my head for direct burial. Just a few things for the OP to consider especially if he decides against hiring it out and wants to do it himself.
 

Greenman

Lifer
Oct 15, 1999
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It was just a suggestion for the OP to consider not by any means a standard or ultimatum to the OP.
Ease of installation and a cheaper installation cost are two factors that I can think of off the top of my head for direct burial. Just a few things for the OP to consider especially if he decides against hiring it out and wants to do it himself.
I believe that conduit doesn't have to be burred as deep as DB cable. Perhaps someone else around here knows for sure.
I don't have any issue with DB cable, it works. But I have seen it fail due to a nick in the sheathing during installation, the was aluminum cable.
 

Skillz

Member
Feb 14, 2014
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^ Some areas of Ohio get past 95F peak in summer. It doesn't seem wise to risk thousands in equipment and electrical setup just to avoid an air conditioner in *most* cases, except that in this case, the load is not something a mere window unit A/C can handle, nor some consumer grade window box fan either.
A window AC unit (or even a portable AC unit) isn't going to have the capability to handle the heat. This is why I suggested just running box fan in a window or two or better would be to install a couple wall mounted exhaust fans w/ shutters up high on the walls to expel the heat.

While 95F is substantially hot it's only ~25F warmer than "controlled room temperature". CPUs and GPUs are designed to run upwards of 70C (158F) or higher. A better solution would be to just upgrade the heatsink/cooling solution of the hardware to better handle the warmer ambient temperatures.

Otherwise, you're looking at installing a central air system heavy enough to handle the power load.

I really appreciate everybody's input! Maybe 5 systems with 3 cards each would be more reasonable. That would probably keep it at a point where a good size window air conditioner could properly cool it. It does get fairly warm where I'm at in the summer, but I ran some PC's in my non air conditioned garage and it seemed to run okay. Of course having a bunch in a closed shed is a totally different situation.
I've lived in Biloxi, MS and now I live in High Point, NC. Both locations I have had ample amounts of systems running throughout the year in a non-air conditioned garage without issue.

The heatsink/cooling solution on these were a lot better than normal though. For example. I ran 2 - 3, 4P AMD G34 systems. These were rack mounted motherboard w/ 4 CPUs per board. Instead of using the passive heatsinks the 2U chassis came with (or the active heatsinks some of the 3U systems had) I removed them and installed Coolermaster 212+ coolers in a dual fan configuration. This kept the temperatures in check during the 100F+ days.

In your situation though; you could easily install some wall mounted exhaust fans to help with that. The garages were not used to park cars, so they stayed closed 99% of the time. Since they were attached garages, cutting a hole in the wall for an exhaust fan was out of the question. A detached shed, on the other hand, would be more fitting for a wall mounted (or 2 or 3) exhaust fans.

100A service should be able to handle 10x 3950x systems with 4x 3080 tiered GPUs. As someone else mentioned 100A service is 240V x 100A which is 24k watts (but you shouldn't go over around 75 - 80% of that) so you're looking at around 19k of useable watts. Go big, or go home. LOL
 

mindless1

Diamond Member
Aug 11, 2001
5,394
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A window AC unit (or even a portable AC unit) isn't going to have the capability to handle the heat. This is why I suggested just running box fan in a window or two or better would be to install a couple wall mounted exhaust fans w/ shutters up high on the walls to expel the heat.

While 95F is substantially hot it's only ~25F warmer than "controlled room temperature". CPUs and GPUs are designed to run upwards of 70C (158F) or higher. A better solution would be to just upgrade the heatsink/cooling solution of the hardware to better handle the warmer ambient temperatures.

Otherwise, you're looking at installing a central air system heavy enough to handle the power load.
That 95F temperature makes it all the more difficult to keep the systems cool enough to promote good lifespan running full out 24/7.

2-3 rather large exhaust fans could work, but not the typical bathroom style pushing 200CFM. 34K BTU is going to raise the temperature dozens of degrees further so your base temperature isn't 95F, rather likely to be over 120F, at INTAKE so with the temperature differential smaller, massive amounts of airflow could be required no matter how great the heatsinks are. Plus, many components don't have heatsinks at all and run within margins because it is assumed the environment won't be this hot.

The best way to attempt this is not allow the heated exhaust to recirculate in the shed, extracting it instead.

Besides, how would you keep the 1KW PSU cool enough? Heatsinks in a PSU are not so easily upgraded. Great effort on an elaborate contraption of custom water cooling everywhere could achieve this in theory but in practice, making the environment correct for standard parts is more sustainable than customizing everything to run hot, short lives.
 

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