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Message 1831566 - Posted: 20 Nov 2016, 13:44:09 UTC

As I have added significant compute capability to support the project recently, I started to have issues with power. I was tripping breakers and had one connection to a UPS that was very hot. I spent the weekend redoing power distribution for my systems and made modifications to hardwire UPS connections. Anyone else run into similar issues? I have posted a couple of videos documenting the problem and my solution: Part 1 and Part 2
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Message 1831575 - Posted: 20 Nov 2016, 14:34:11 UTC

At my last job I had a rack of older PowerEdge 2850 servers and only two 120v 20a power drops to feed it. I ended up having to seek a few other outlets across the room to get everything up and going. The UPS's were connected to the mains with 10' 14-3 cords, but were always a bit warmer than ambient.

Recently at home I've been working on identifying what breakers are tied to what. Since I have systems in a bedroom, living room and a loft over the loving room. I am hoping the left outlets are not tied to the living room. I have considered taking the unused 240v electric dryer outlet, as I have a gas dryer,and have some new high amp outlets installed in my loft for dedicated computer stuff. Then I could switch several things to 240v which supposedly gains a few % in efficiency with computer PSUs.
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Message 1831587 - Posted: 20 Nov 2016, 15:17:01 UTC

Those UPSs are pretty incredible! I was looking at bigger units when crunchers were getting too hungry but my wife pointed out that if they're just working for SETI a power-failure isn't a big deal. I could use a much nicer surge protector, though.

I couldn't get away with hard-wiring anything -- my limit is the existing power infrastructure so that I don't get too carried away. In some ways I envy your lack of regulation but at the same time I'm glad I have that constraint!
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Message 1831597 - Posted: 20 Nov 2016, 16:39:44 UTC - in response to Message 1831566.  
Last modified: 20 Nov 2016, 16:39:54 UTC

I was tripping breakers and had one connection to a UPS that was very hot.

As long as the load is within specification for the outlet, it shouldn't get hot; running near it's limit it will get warm but it still shouldn't become hot. If it is, then it indicates a faulty outlet/plug resulting in heat.
If the load is out of spec, then heat is to be expected, and you need to bring it back within spec.
Fire is something to avoid.

Was the breaker tripping due to load, or earth leakage?
In my previous house I had 2 computers running on their own UPS units through the same power outlet for several years with no issues. Then the earth leakage started tripping on random occasions.
Put one system on a different circuit & everything was happy again.
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Message 1831648 - Posted: 20 Nov 2016, 23:50:53 UTC

You probably have already found this info, but figured I'd toss it in here if you had not for your cable sizing.
US Standards for a 30A circuit are 10 AWG minimum in most situations (sizes go up for long runs), but you can always go up a size in a shorter run for a lower voltage drop across the cable. Normally the extra cost of the large cables isn't justified but for larger power usage situations, like yours, it is likely worth the extra expense.
AWG	Inches	MM
6 	0.162 	4.11
7 	0.1443 	3.67
8 	0.1285 	3.26
10 	0.1019 	2.59
12 	0.0808 	2.05
14 	0.0641 	1.63
16 	0.0508 	1.29
18 	0.0403 	1.02

The 3.5mm cabling you went with is some pretty heavy duty stuff. As someone with an electrical engineering degree I completely approve!
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Message 1831654 - Posted: 21 Nov 2016, 0:25:40 UTC - in response to Message 1831648.  

You probably have already found this info, but figured I'd toss it in here if you had not for your cable sizing.
US Standards for a 30A circuit are 10 AWG minimum in most situations (sizes go up for long runs), but you can always go up a size in a shorter run for a lower voltage drop across the cable. Normally the extra cost of the large cables isn't justified but for larger power usage situations, like yours, it is likely worth the extra expense.
AWG	Inches	MM
6 	0.162 	4.11
7 	0.1443 	3.67
8 	0.1285 	3.26
10 	0.1019 	2.59
12 	0.0808 	2.05
14 	0.0641 	1.63
16 	0.0508 	1.29
18 	0.0403 	1.02

The 3.5mm cabling you went with is some pretty heavy duty stuff. As someone with an electrical engineering degree I completely approve!


In the video, I said mm when it is actually mm2, so this conversion table applies.
AWG    mm     inch      mm2
7    3.6649  0.1443  10.5488
8    3.2636  0.1285   8.3656
9    2.9064  0.1144   6.6342
10   2.5882  0.1019   5.2612
11   2.3048  0.0907   4.1723
                      3.5000 (new wire)
12   2.0525  0.0808   3.3088
13   1.8278  0.0720   2.6240
14   1.6277  0.0641   2.0809 (original wire)


So it is not quite that impressive. I checked out the 5mm2 triple wire cabling and it was just too massive to work with. US standards are more conservative than international, but having trouble finding the table that led me to believe this. Looks like I should not attempt to push to 30A on the line to my desktop with this cable.
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Message 1831655 - Posted: 21 Nov 2016, 0:31:32 UTC - in response to Message 1831654.  

I find this page a useful reference.
AWG Wire Sizes.
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Message 1831658 - Posted: 21 Nov 2016, 0:42:51 UTC

Years ago, I ran a 10 guage 50 amp 240v subfeed to the livingroom where my crunchers are with a dedicated breaker to feed it.
I had (ahem) tried to burn the shack down by overloading the standard branch circuits.
Being a licensed eletrician, I should have known better.
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Message 1831660 - Posted: 21 Nov 2016, 0:53:04 UTC - in response to Message 1831658.  
Last modified: 21 Nov 2016, 0:53:20 UTC

One of the advantages of 240V over 120V, half the current for the same load.
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Message 1831663 - Posted: 21 Nov 2016, 1:05:35 UTC - in response to Message 1831654.  

[quote]You probably have already found this info, but figured I'd toss it in here if you had not for your cable sizing.
US Standards for a 30A circuit are 10 AWG minimum in most situations (sizes go up for long runs), but you can always go up a size in a shorter run for a lower voltage drop across the cable. Normally the extra cost of the large cables isn't justified but for larger power usage situations, like yours, it is likely worth the extra expense.
AWG	Inches	MM
6 	0.162 	4.11
7 	0.1443 	3.67
8 	0.1285 	3.26
10 	0.1019 	2.59
12 	0.0808 	2.05
14 	0.0641 	1.63
16 	0.0508 	1.29
18 	0.0403 	1.02

The 3.5mm cabling you went with is some pretty heavy duty stuff. As someone with an electrical engineering degree I completely approve!/quote]

In the video, I said mm when it is actually mm2, so this conversion table applies.
AWG    mm     inch      mm2
7    3.6649  0.1443  10.5488
8    3.2636  0.1285   8.3656
9    2.9064  0.1144   6.6342
10   2.5882  0.1019   5.2612
11   2.3048  0.0907   4.1723
                      3.5000 (new wire)
12   2.0525  0.0808   3.3088
13   1.8278  0.0720   2.6240
14   1.6277  0.0641   2.0809 (original wire)


So it is not quite that impressive. I checked out the 5mm2 triple wire cabling and it was just too massive to work with. US standards are more conservative than international, but having trouble finding the table that led me to believe this. Looks like I should not attempt to push to 30A on the line to my desktop with this cable.


Oh I missed the mm2. That does make a slight difference. So it looks like you basically have 12 AWG cable. Which is standard US 20a circuit wiring. However I think the 20A rating is for solid cable. I'd have to look up the ratings for stranded cabling. I'd guess it might be 25A, but probably not 30A. Even though it might handle 30A fine 24/7 it would likely run warmer, and likely why the US standards go up to the next size for 30A. Given you are already in the 25-30ºC range I personally wouldn't want to see much more from my cabling.

I mostly use 14AWG power cables for my PC to UPS connections and they are all sub KW systems. Mostly because I like overkill when it comes to power related things like that. I did once buy a 10 foot section of 10,000 strand 000AWG cable to use as a ground for some Tesla Coil stuff I was doing.
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Message 1831666 - Posted: 21 Nov 2016, 1:39:58 UTC - in response to Message 1831663.  

Oh I missed the mm2. That does make a slight difference. So it looks like you basically have 12 AWG cable. Which is standard US 20a circuit wiring. However I think the 20A rating is for solid cable. I'd have to look up the ratings for stranded cabling. I'd guess it might be 25A, but probably not 30A. Even though it might handle 30A fine 24/7 it would likely run warmer, and likely why the US standards go up to the next size for 30A. Given you are already in the 25-30ºC range I personally wouldn't want to see much more from my cabling.

I mostly use 14AWG power cables for my PC to UPS connections and they are all sub KW systems. Mostly because I like overkill when it comes to power related things like that. I did once buy a 10 foot section of 10,000 strand 000AWG cable to use as a ground for some Tesla Coil stuff I was doing.


Typical wiring through out the house is 2.0mm2 (14AWG), so the wiring up to my new UPS mini-breaker box is only 2.0mm2. From the box to the UPS is 3.5mm2. From UPS to the line that feeds the outlets for my desktop is 3.5mm2 and from there to the desktop is 5mm2. In the breaker box, it is using a 20A breaker. Now that I have added a Network Management Card to the UPS, I can see it is only drawing about 5A, but that was without my laptop and Zotac nano system powered up. I also want to have a third test system powered up at times. Seems like all of that will fit in 20A...maybe.
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Message 1831667 - Posted: 21 Nov 2016, 1:44:55 UTC - in response to Message 1831575.  

At my last job I had a rack of older PowerEdge 2850 servers and only two 120v 20a power drops to feed it. I ended up having to seek a few other outlets across the room to get everything up and going. The UPS's were connected to the mains with 10' 14-3 cords, but were always a bit warmer than ambient.

Recently at home I've been working on identifying what breakers are tied to what. Since I have systems in a bedroom, living room and a loft over the loving room. I am hoping the left outlets are not tied to the living room. I have considered taking the unused 240v electric dryer outlet, as I have a gas dryer,and have some new high amp outlets installed in my loft for dedicated computer stuff. Then I could switch several things to 240v which supposedly gains a few % in efficiency with computer PSUs.


Sounds like the situation I was in before this modification. Definitely concerned that the extension cords would eventually cause big problems. If only I knew the scale this would eventually evolve to, I would have went with 220V for power distribution...
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Message 1831668 - Posted: 21 Nov 2016, 1:48:16 UTC - in response to Message 1831587.  

Those UPSs are pretty incredible! I was looking at bigger units when crunchers were getting too hungry but my wife pointed out that if they're just working for SETI a power-failure isn't a big deal. I could use a much nicer surge protector, though.

I couldn't get away with hard-wiring anything -- my limit is the existing power infrastructure so that I don't get too carried away. In some ways I envy your lack of regulation but at the same time I'm glad I have that constraint!


My wife is starting to question how much I spend on this. I hope I can get through my new workstation build before she cuts me off. The lack of regulation in Taiwan definitely has its downside. So much bad work done by contractors. That's why I decided to do this myself.
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Message 1831669 - Posted: 21 Nov 2016, 1:54:35 UTC - in response to Message 1831597.  

I was tripping breakers and had one connection to a UPS that was very hot.

As long as the load is within specification for the outlet, it shouldn't get hot; running near it's limit it will get warm but it still shouldn't become hot. If it is, then it indicates a faulty outlet/plug resulting in heat.
If the load is out of spec, then heat is to be expected, and you need to bring it back within spec.
Fire is something to avoid.

Was the breaker tripping due to load, or earth leakage?
In my previous house I had 2 computers running on their own UPS units through the same power outlet for several years with no issues. Then the earth leakage started tripping on random occasions.
Put one system on a different circuit & everything was happy again.


With the new UPS and its Network Management Card, I can see it is only pulling ~5A, so it was well within spec. Probably just a low quality extension cord.

For the breaker tripping, I am certain it was overloaded. Both my main crunchers were on that circuit, which run at almost 2000W. This happened when I moved my Triple ProDuo system into the network closet while I wait for parts to rebuild it as my main desktop. Now the Penta-Nano system runs on its own breaker and wall outlets in the network closet also have a dedicated breaker.
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Message 1831670 - Posted: 21 Nov 2016, 1:56:54 UTC - in response to Message 1831660.  

One of the advantages of 240V over 120V, half the current for the same load.


Yes, I wish I would have went with 220V power distribution in my network closet. That would have been much more effective. Now I have too much invested in 110V.
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Message 1831671 - Posted: 21 Nov 2016, 1:58:32 UTC - in response to Message 1831655.  

I find this page a useful reference.
AWG Wire Sizes.


Thanks for the table! When I was doing the project I found a table giving wire diameter vs. US/EU/International current ratings. Having trouble locating that table again.
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Message 1831673 - Posted: 21 Nov 2016, 2:02:48 UTC - in response to Message 1831658.  

Years ago, I ran a 10 guage 50 amp 240v subfeed to the livingroom where my crunchers are with a dedicated breaker to feed it.
I had (ahem) tried to burn the shack down by overloading the standard branch circuits.
Being a licensed eletrician, I should have known better.

Can't imagine the power distribution you have to support getting to 1 Billion credits! Now that temps are down, have you powered up all of your crunchers?
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Message 1831675 - Posted: 21 Nov 2016, 2:10:36 UTC - in response to Message 1831673.  

Years ago, I ran a 10 guage 50 amp 240v subfeed to the livingroom where my crunchers are with a dedicated breaker to feed it.
I had (ahem) tried to burn the shack down by overloading the standard branch circuits.
Being a licensed eletrician, I should have known better.

Can't imagine the power distribution you have to support getting to 1 Billion credits! Now that temps are down, have you powered up all of your crunchers?

All 8 are rockin'.
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Message 1831676 - Posted: 21 Nov 2016, 2:12:29 UTC - in response to Message 1831673.  
Last modified: 21 Nov 2016, 2:22:58 UTC

Not sure about your local utility support but I have quite a few teammates that have had to have the utility company "upgrade" some or all of there service.

In the US you can get about ~1800w (~15amps @ 120v service) per circuit for residential, a few GPUS and CPUs can add up quickly and hit that 1800w pretty quickly and trip a breaker.

So either spread out your systems across more circuits or get higher rated circuits.
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Message 1832391 - Posted: 25 Nov 2016, 17:55:34 UTC
Last modified: 25 Nov 2016, 17:56:14 UTC

I'm in the process of adding three 20 amp circuits to my basement, two 240v and one 120v, to eventually run a small farm. Everything I run is 10 gauge wire in Greenfield, and any circuit I add is always 20 amp. True, being a little thicker it is a bit more of a PITA to work with, but the actual difference in material costs are pretty insignificant, and there is then more amperage available, and potentially less voltage drop. I've never had a issue when I overbuilt something, but the few times I tried to do it 'just good enough' have more often than not come back to bite me in the butt down the road, so I've learned that it just doesn't pay to do that.

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Message boards : Number crunching : Power Distribution


 
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