What are the requirements of your PDU? Chances are that it will take single or three phase power, but not "either / or". If you're going to be metered separately from the other tenants, you might find that the fixed charge for three-phase power is much higher than single phase power from your electric company. Additionally, all of your wiring and accessories will be more expensive if you use three phase power.
I might also guess that the building HVAC and elevators are powered off of the three-phase panel - which means that you may have additional electrical noise on that buss.
Unless you're talking about building a mainframe data center, my vote would be for single phase power.
I think you made some mistakes.......
[1] It was marked 240V to neutral, not 208V.
[2] The biggest current rate breaker is 20A, you cannot get out 30A from a single existed breaker unless
you install a new breaker.
[3] The wiring is so messy and non professional.
[4] From picture #1 , all black units were picked together and block most their heat circulation holes on top.
Those units will not last too long due to overheated.
Typically you get 208 from between phases (for 3-phase), then 120 volt for each phase to neutral (in a Y configuration, which is usually the 4 wires). Most of your computers would be 120V in the United States. Many have switching power supplies, which can handle more than one voltage, or there is a switch to change between 120V and 240V.
Best bet would be to get an electrician or somebody from the electric company to tell you what you have.
About an amp each at 240V or 2 amps each at 120V should be plenty unless they're super high end computers. Make sure the voltage matches what it says on the power supplies. not under or over, so you don't damage them. Most power supplies can handle 240V but check it and make sure. So probably you'll need the 240V.
You don't want to guess on something like this. Find out exactly what voltage your computers need and get it installed.
I just secured my first commercial office space and I have an agreement with the landlord to either get a 208V 30A outlet installed or a 240V 30A. When I went into the breaker room on my floor, I found 2 separate boxes. 1 controls office outlets. The other one is 3phase/4wire delta and controls high power items like heaters. I've included a link to 15+ pictures of everything in the breaker room on my floor at the bottom of this post. Bottom line, I need 6000-7000W of continuous power. I'm going to have a PDU hooked into the 208V or 240V outlet and then 8-10 computers(not servers) running off of that PDU at once for stress testing. What would my best option be with this building to achieve that? I'm guessing 208V/30A line out of the 3phase/4wire delta that's powering the heat? What if he doesn't allow me to make modifications on that because it's dedicated, then what would my best option be?
Information that may or may not be relevant:
The building was built in the late 1800s but seems to have updated power.
It has 6 floors(I'm on the 5th), approximately 5 offices per floor and around 70% occupancy(may or may not be relevant for power load?)
Link to 15+ pictures of breaker room:
http://imgur.com/uAtW9qZ,pKilT1L,jr2dDAs,QWvDacC,8BI6lUN,wFhmeTR,x6HvxIa,8k4rmnt,FwIzYuv,KnuDekE,vSpyB9P,qV4IraE,0INeC0E,TUei16C,ctFvGid,zcUMyBn,GjmgFvw,DyjAoWi,Bhx0o1E,CMNGwik#4
