Power Configuration [BOUNTY 5BTC]

[Scared]

I'm about to spend a bunch of cash in an area that I'm not familiar with. I've done a bunch of research and would like your help. I'll donate 5 BTC to whoever can confirm my approach or suggest a better solution.

I will be running 9 mining rigs each with 4x7970s pulling just about 1150 watts each via two 750 Watt Power supplies. I've calculated that at 208 Volts that each machine will pull 5.53 amps or 49.76 amps to support all 9 machines.

I've been fortunate enough to get a lease that includes electricity and A/C. The office suite comes with a NEMA 10-50 Socket 50 Amps @ 250V. I've contracted an electrician to replace the outdated NEMA Socket with a CA STD CS8265C (California Style 50 Amp, 250 Volt, 3 wire Twistlock Plug). That will allow me to use the Geist ZP090-105C19CS6 50 Amp PDU (http://www.stayonline.com/detail.aspx?ID=13298). I will then use C20 to 2 Way C13 cord (http://www.stayonline.com/detail.aspx?ID=18940) to plug in each of the powers supplies (two to each rig).

It's going to run me $919 for the PDU/Power cords and about $400 for the electrician to change out the power socket. Is this the best way to go or is there a better option?

[1714043061]

1714043061

[rjk]

Well for one thing, you ought to be able to replace that outlet yourself, that would save you a bit. Unless there is some regulation that says you aren't allowed to, or that you have to be licensed?

The PDU is a good idea, but damn that is expensive.  

EDIT: Some alternatives on ebay:

1: http://www.ebay.com/itm/200732820785
2: http://www.ebay.com/itm/310391058869

and others.

[Scared]

Well for one thing, you ought to be able to replace that outlet yourself, that would save you a bit. Unless there is some regulation that says you aren't allowed to, or that you have to be licensed?

The PDU is a good idea, but damn that is expensive.  

EDIT: Some alternatives on ebay:

1: http://www.ebay.com/itm/200732820785
2: http://www.ebay.com/itm/310391058869

and others.

I've chosen to go with a licensed electrician since I'm leasing the office space. I don't want to take any chances and cause a fire.

The part the I'm most confused by is Three Phased solutions. From what I hear it's best to stay away from it. I believe my existing NEMA 10-50 Outlet is not three phase and that's why I'm looking at Geist ZP090-105C19CS6 50 Amp PDU since it does not require it. Both items you found on EBay are three phased.
In my research I found that almost every solution above 30 Amps seemed to be three phased. The Geist was the only PDU that I could find that worked on a normal circuit.

[rjk]

Oops, my bad I didn't notice that. Yeah single phase PDUs above 30 amps are rare, but as another poster mentioned, maybe a subpanel would be a good idea.

[DeathAndTaxes]

I'd buy PDU(s) that can be controlled from the network.  If one of your rigs goes down, becomes unresponsive,
you should setup a monitor server and power cycle a faulty rig.

Insanely expensive.  Remember PDU are rated on maxed switched capacity and even 5 KW PDU are $500+.

[Cobra]

I have one of these Tripplite PDU's (first link) running off of 240v.  I found it on sale for under $300, right now this one is $519 but still cheaper than the option you are looking at. Although I did buy all my power cords from Stayonline.com, happy with the purchase from them. I have mine hooked up to network, to my surprise this device does not tell you how much power each port uses, the led on the bank will only tell you how many amp each bank uses. I felt the interface and features were really lacking. In my case 3.8GH using 7amp. Max of this device is 24amp.

http://www.amazon.com/Tripp-Lite-PDUMH30HVNET-Distribution-Switching/dp/B0013HY9E2/ref=sr_1_14?s=electronics&ie=UTF8&qid=1333123661&sr=1-14

If I had it to do over I would probably go with the cheaper version without the network monitoring for $257.  It has been stable and just never use that feature.

http://www.amazon.com/Tripp-Lite-PDUMH30HV-Metered-L6-30P/dp/B0053YIUPK/ref=sr_1_12?s=electronics&ie=UTF8&qid=1333123661&sr=1-12

[DeathAndTaxes]

How much wattage do you need?  Is 5.76 KW enough?  If so you can do it for <$100.

30A single phase is going to be the cheapest bang for the buck.  You get used one for <$50 on ebay (sometimes <$30 shipped if you wait for deals).

Those California Connectors are insanely expensive.  I would avoid them like the plague unless your local code PROHIBITS NEMA-6.  Most places simply recommend the CA connector over NEMA-6.  You could have electrician rewire it for NEMA 6 configuration (hot, hot, ground) which is going to be a lot cheaper setup.  It will require changes at both the outlet and the breaker but should be pretty routine.  
If you can get by with 5.7KW (or have multiple outlets which can be rewired I would do this)

1) Replace the NEMA 10-50 with a NEMA 10-30 outlet. ($15 in parts)
2) Buy a AP9571 PDU.  They are cheap on ebay ($50 tops sometimes a lot less).
3) Do the wiring yourself it honestly isn't very hard or pay an electrician to do it (but I would shop around, rewiring an outlet is a <1 hr job - he is burning you for ~$600/hr to $100/hr)
4) Buy some standard C13 to C14 cables ($4 ea)

Why the AP9571?  Beacause APC made a quadrillion of them so used ones as always on ebay.
208V/240V.
30A (24 derated)
12 C14 outlets
Single NEMA L6-30P plug with 20ft very very thick cord.

Pretty much no PDU gives you a lower cost per KW.

Here is an example:
http://www.ebay.com/itm/APC-Basic-Rack-Mount-PDU-1U-AP9571-208VAC-30A-IEC-320-12-C13-NEMA-L6-30P-/130672139930?pt=LH_DefaultDomain_0&hash=item1e6caa9e9a

If you need more than 5.76KW (or want to later expand) I would install 2x NEMA L6-30 outlets.
Does the property have 2x NEMA-10 outlets?  If so then you can go to 11KW for ~$220 (plus optionally electrician labor).  The other option (and no this isn't code compliant) would be to have electrician install a NEMA L6-50 outlet and then wire a Y adapter using a NEMA L6-50 socket and 2x NEMA L6-30 plugs.  There is no danger BUT if you want to be safe ensure the combined load of the 2x PDU is <40A.

On edit: I see you indicated needing 49A.  To be code compliant no 50A PDU will allow 50A of draw.  They are derated 20%.  US Electrical code prohibits using more than 80% of circuit rated capacity for continual loads.  So 50A PDU will have an internal circuit breaker at 40A (likely 2x 20A breakers).

[Scared]

I'd buy PDU(s) that can be controlled from the network.  If one of your rigs goes down, becomes unresponsive,
you should setup a monitor server and power cycle a faulty rig.

Since you already have 50A@250V, why not put up a subpanel and distribute power to each smaller PDU.
Each PDU can drive 1-2 rigs.  

BTW, If you don't OC them too hard, you can setup 10 rigs off that 50A@250V

Think about maintenance, not just getting it up and running.

I've thought about using a subpanel but decided against it since I found a single PDU that can can distribute the load and I'm assuming that installing subpanel will be much more expensive than changing a socket. I tried to find a network controlled 50 Amp non-three phased PDU and couldn't find it.

I believe the OC for the 7970 costs less than 50Watts per card and gives a 165 MHash improvement. If I didn't OC the entire farm i'd save 1800 Watts and loose 5940 MHash over all 9 machines. If I was to add an additional machine that would take 1000 Watts and provide an additional 2220 MHash. My power would be reduced by 800 watts and I would loose 3730 MHash even with the the additional machine in an non OC senario. In todays market that would net me a loss of $315 a month. As long as 7 cards don't die within a year i'm more profitable with the OC then otherwise.

 

[DeathAndTaxes]

google: PDU+Ethernet port+price

Take your pick.

http://www.techforless.com/cgi-bin/tech4less/AP7820?mv_pc=nextag&tts=20120330072104

http://www.apc.com/resource/include/techspec_index.cfm?base_sku=AP7820&tab=documentation

Yeah that was my point.  
Per the link 12A. The OP would need 5x of those = $500+.
Also that is a metered not switched PDU.  Switched version is double so it is more like $1000+.

vs

30A (24A derated) "basic" used PDU = $50.

I didn't say they don't exist .... I said they are expensive.

[Scared]

I have one of these Tripplite PDU's (first link) running off of 240v.  I found it on sale for under $300, right now this one is $519 but still cheaper than the option you are looking at. Although I did buy all my power cords from Stayonline.com, happy with the purchase from them. I have mine hooked up to network, to my surprise this device does not tell you how much power each port uses, the led on the bank will only tell you how many amp each bank uses. I felt the interface and features were really lacking. In my case 3.8GH using 7amp. Max of this device is 24amp.

http://www.amazon.com/Tripp-Lite-PDUMH30HVNET-Distribution-Switching/dp/B0013HY9E2/ref=sr_1_14?s=electronics&ie=UTF8&qid=1333123661&sr=1-14

If I had it to do over I would probably go with the cheaper version without the network monitoring for $257.  It has been stable and just never use that feature.

http://www.amazon.com/Tripp-Lite-PDUMH30HV-Metered-L6-30P/dp/B0053YIUPK/ref=sr_1_12?s=electronics&ie=UTF8&qid=1333123661&sr=1-12

I looked at these solutions but unfortunately 30Amps will not power all 9 machines. I need a minimum of 50Amps. I don't want to pay the electrician to run new lines if I can get it to work off the existing 50Amp Line. 

[DeathAndTaxes]

I looked at these solutions but unfortunately 30Amps will not power all 9 machines. I need a minimum of 50Amps. I don't want to pay the electrician to run new lines if I can get it to work off the existing 50Amp Line.  

Well pulling 50A continual load on a circuit reated for 50A is a code violation anyways so if you want to violate code then I would go with:
NEMA 6-50 outlet (or CA connector but they are much more expensive)
custom Y adapter (L6-50P -> 2x L6-30R)
2x $50 used 30A PDU
Just make sure to keep wattage down below 40A (maybe put 1 of 9 rigs on a seperate circuit).

Are there any other 230V outlets (50A or otherwise)?

On edit: one last option would be to determine if the wire can handle 60A (it may). You (or electrician) will need to see is part of insulation is visible to get type, gauge, and temp rating of the wire.

http://lugsdirect.com/WireCurrentAmpacitiesNEC-Table-301-16.htm

If the wire is rated for 60A (my guess would be it is 6 gauge 70C) then you could replace the 50A breaker w/ 60A breaker ($25 part) and install a pair of NEMA L6-30 outlets ($40 in parts plus labor).  A pair of used (ebay) 30A PDU ($50 ea) would give you 48A usable and you wouldn't violate the 20% derate requirement for continual loads.

Note: the derate requirement is important.  With variable loads the conductor will get a chance to "cool off" between duty cycles.  With a continual load you are pushing the wire closer to max rating 24/7.  Any defect or failure could cause an ignition event behind the wall.  Now do I think 50A continual on a 50A circuit is going to cause a fire?  Probably not but the electrical code is intentionally conservative.

[Scared]

I looked at these solutions but unfortunately 30Amps will not power all 9 machines. I need a minimum of 50Amps. I don't want to pay the electrician to run new lines if I can get it to work off the existing 50Amp Line.  

Well pulling 50A continual load on a circuit reated for 50A is a code violation anyways so if you want to violate code then I would go with:
NEMA 6-50 outlet (or CA connector but they are much more expensive)
custom Y adapter (L6-50P -> 2x L6-30R)
2x $50 used 30A PDU
Just make sure to keep wattage down below 40A (maybe put 1 of 9 rigs on a seperate circuit).

Are there any other 230V outlets (50A or otherwise)?

On edit: one last option would be to determine if the wire can handle 60A (it may). You (or electrician) will need to see is part of insulation is visible to get type, gauge, and temp rating of the wire.

http://lugsdirect.com/WireCurrentAmpacitiesNEC-Table-301-16.htm

If the wire is rated for 60A (my guess would be it is 6 gauge 70C) then you could replace the 50A breaker w/ 60A breaker ($25 part) and install a pair of NEMA L6-30 outlets ($40 in parts plus labor).  A pair of used (ebay) 30A PDU ($50 ea) would give you 48A usable and you wouldn't violate the 20% derate requirement for continual loads.

Note: the derate requirement is important.  With variable loads the conductor will get a chance to "cool off" between duty cycles.  With a continual load you are pushing the wire closer to max rating 24/7.  Any defect or failure could cause an ignition event behind the wall.  Now do I think 50A continual on a 50A circuit is going to cause a fire?  Probably not but the electrical code is intentionally conservative.

Great information much appreciated even though it's not what I wanted to hear. It's clear from what your saying that I can't use a 50Amp /  208 Volt supply for my farm and it got me thinking. What determines if the line is 208/240/250 Volts. I looked at the NEMA 10-50 Socket again and noticed it says 250V. I assumed it was 208V since that seems to be what most PDUs reference. How do I know what voltage my line actually is? Should I go with what's written on the socket? Can the voltage be changed at the circuit breaker or do you need to have the building wired for different voltages?

If the line is 250V as the socket says then the farm will pull 41.4 amps and wouldn't that put it within tolerance of the code requirements??? I do have several 110V Lines that I can use to make sure the circuit stays at/under 40amps.


 

[rjk]

250 Volts is just the maximum tested and allowed voltage for the plug/receptacle itself, the actual voltage will need to be measured with a meter. Common voltages are 208, 220, and 240 volts, depending on where you are.

I'm not 100% sure why they are different, but I believe it is due to whether the service is wye or delta phasing.

[Scared]

I just purchased a multimeter and measured the voltage at the NEMA 10-50 Socket. Each of the two lines is 120V. So that makes it a 240V circuit.

So if I power only 8 rigs through the PDU i'll pull only 40 Amps and will be within code. I can then place everything else on the 110V line.

When I'm ready to expand I'll go the route that DeathAndTaxes suggested and install new 30Amp lines using NEMA 6 sockets.

[DeathAndTaxes]

What determines if the line is 208/240/250 Volts. I looked at the NEMA 10-50 Socket again and noticed it says 250V. I assumed it was 208V since that seems to be what most PDUs reference. How do I know what voltage my line actually is? Should I go with what's written on the socket? Can the voltage be changed at the circuit breaker or do you need to have the building wired for different voltages?

Ah the ole 208V/220V/230V/240V/250V question.

So what is 208V?

In the US the only place 208V exists is when tapping between two phases of a 3 phase circuit.   Datacenters and industrial buildings will be supplied power using 3 phases where each line is 120V potential with the ground.  Each line is out of phase from the other two.   Tapping from one phase to another results in a 208V circuit.  It allows more circuits to be installed on one wiring run (among other reasons).  

All the rest of the power in the US is 120V/240V split phase where two 120V mains are supplied.  Tapping between them gets you 240V.  Tapping either of the 120V mains to the neutral gets you 120V.  That is how homes in US can have both 120V and 240V using only 3 wires (leg1, leg2, and neutral) from the street.

If all that was confusing don't worry about it.  The important part is that 208V circuits only exist in buildings wired for 3phase power.
The good news a PDU designed for 208V should work fine at 220V-240V.  Some brands will even write it like that (208V/230V).

The APC 30A models I listed above are designed for 208V circuits but work fine with 240V.  The only thing to worry about would be a 3 phase 208V PDU.  A PDU listed as 3 phase 208V is designed to take the ENTIRE 3 phase circuit (rather than split 3 phase circuit into 3x 1 phase circuits).  Connecting that to non 3phase wiring would be very very bad.  Good news is they use completely different plugs so you would have to try hard to get it connected.

So why do some things say 220V, some 230V, some say 240V?  
Stupidity?  Voltage in the US is often called 110V/220V but it isn't.  It is actually 115V/230V however it can vary from location to location and even on time of day.  

Generally speaking:
220V/230V/240V all refer to the same thing.
110V/115V/120V all refer to the same thing.

You can't change your voltage (well not in any way that is useful).  Your voltage depends not only on the building but the mains supplied by the power company.  You got what you got.

So what is 250V?
Nothing runs @ 250V the connectors are simply rated @ 250V.  Which means it can safely handle 0V to 250V which covers 208V and 230V.

[DeathAndTaxes]

I just purchased a multimeter and measured the voltage at the NEMA 10-50 Socket. Each of the two lines is 120V. So that makes it a 240V circuit.

It you measure it hot to hot it should read 240V.  I assume you were measuring it hot to neutral which would should read 120V.

So if I power only 8 rigs through the PDU i'll pull only 40 Amps and will be within code. I can then place everything else on the 110V line.

That will work but $900 for a PDU plus $400 for electrician is highway robbery.  Even if you want an electrician I would ask him if he can check on upgrading the circuit.   If the wiring can handle 60A then upgrading the breaker and installing 2x L6-30 is going to give you more power and cheaper wiring options ($100 vs $900).

[Inspector 2211]

I've been fortunate enough to get a lease that includes electricity and A/C.

I would suggest that you don't purchase all nine rigs immediately, but start with, say, three and find out whether the A/C can actually get rid of the heat of 3 rigs nicely, leaving the room at 72 or 74 maybe even 78 degrees Fahrenheit.
Because chances are, the A/C (and/or the air duct system) is not designed to get rid of 10,000 W - maybe it is only designed  for two or three humans at 250W each and a single desktop PC at 250W.

I had an office in Palo Alto with 8 rigs drawing a total of 4,000 W and the only way I could avoid thermal meltdown was opening the window and putting the rigs on the windowsill, their rear facing outwards. Eventually they kicked me out for using excessive electricity ("breach of contract").

Currently I have an office in Santa Clara with 3 rigs drawing 2,000 W, but the window cannot be opened and thus I cannot turn on more rigs. Even so, it gets hot like in a sauna and when I spend any extended period of time there, I have to take off my shirt and sit there in my undershirt...

[Scared]

I just purchased a multimeter and measured the voltage at the NEMA 10-50 Socket. Each of the two lines is 120V. So that makes it a 240V circuit.

It you measure it hot to hot it should read 240V.  I assume you were measuring it hot to neutral which would should read 120V.

So if I power only 8 rigs through the PDU i'll pull only 40 Amps and will be within code. I can then place everything else on the 110V line.

That will work but $900 for a PDU plus $400 for electrician is highway robbery.  I would check to see if the wiring can handle 60A.  If it can upgrading the breaker to 60A and replacing the single NEMA 10-50 with a pair of L6-30 will be like 1/3rd of the cost and give you 48A usable.

So I didn't measure hot-hot.. Didn't think that was a wise idea at the time.. So after you mentioned it I decided I'd go measure it and found it's reading only 208V?!?!?! I double checked the Hot to Neutral and it's 120V. Show does 120V + 120V = 208V???

[Scared]

I've been fortunate enough to get a lease that includes electricity and A/C.

I would suggest that you don't purchase all nine rigs immediately, but start with, say, three and find out whether the A/C can actually get rid of the heat of 3 rigs nicely, leaving the room at 72 or 74 maybe even 78 degrees Fahrenheit.
Because chances are, the A/C (and/or the air duct system) is not designed to get rid of 10,000 W - maybe it is only designed  for two or three humans at 250W each and a single desktop PC at 250W.

I had an office in Palo Alto with 8 rigs drawing a total of 4,000 W and the only way I could avoid thermal meltdown was opening the window and putting the rigs on the windowsill, their rear facing outwards. Eventually they kicked me out for using excessive electricity ("breach of contract").

Currently I have an office in Santa Clara with 3 rigs drawing 2,000 W, but the window cannot be opened and thus I cannot turn on more rigs. Even so, it gets hot like in a sauna and when I spend any extended period of time there, I have to take off my shirt and sit there in my undershirt...

I've already got 3 rigs running without any issues. I'm expanding to 9 after the power issues are addressed. Regarding AC from what I could learn on the net it's clear what I need to plan for -
   1200 Watts per Rig * 9 Rigs = 10,800 Watts of power  (45 Amps)
   To convert that to BTU I've read you multiply by 3.413 giving me 36,860 BTU
   And then to convert that to AC Tonnage divide by 12000 bringing my requirement to a 3 Ton AC Unit
 
The office I'm in has a dedicate 4 ton AC Unit. So if i'm to trust my knowledge I gained from googling this crap I should be okay...


 

[DeathAndTaxes]

So I didn't measure hot-hot.. Didn't think that was a wise idea at the time.. So after you mentioned it I decided I'd go measure it and found it's reading only 208V?!?!?! I double checked the Hot to Neutral and it's 120V. Show does 120V + 120V = 208V???

It should look like this:



W = neutral
X = one 115V leg
Y = one 115V leg
There is no ground on this outlet which is why it is obsolete.

X -> Y should be ~230V (220V-240V)
X -> W should be ~115V (110V-120V)
Y -> W should be ~115V (110V-120V)