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theduude

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Detroit MI
I'm not an electrical engineer but I've been browsing the forums and it seems as though the people here are very knowledgeable. I am a computer repairman that has specific power needs. 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. Ok, so, mainly I need 6000-7000W of continuous power because 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?

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,jr...Gid,zcUMyBn,GjmgFvw,DyjAoWi,Bhx0o1E,CMNGwik#4
 
The receptacle you need is the one that matches the PDU you're going to use, but assuming that these are not high-powered servers, the output of the PDU will be 120v, so the input is probably going to be 120/208v. There will be a designation on the PDUs plug like "L14-30" or "L21-20" (or "120/208v 20a"); give that info to the electrician. That's all they need to install the right thing.

Also, 8 or 10 normal desktop systems are not going to draw anywhere near 6kw unless each one has a large CRT monitor and lots of hard drives.
 
zbang said:
The receptacle you need is the one that matches the PDU you're going to use, but assuming that these are not high-powered servers, the output of the PDU will be 120v, so the input is probably going to be 120/208v. There will be a designation on the PDUs plug like "L14-30" or "L21-20" (or "120/208v 20a"); give that info to the electrician. That's all they need to install the right thing.

Also, 8 or 10 normal desktop systems are not going to draw anywhere near 6kw unless each one has a large CRT monitor and lots of hard drives.
Click to expand...

They aren't normal, some of them will have 3 7990s running(7990 graphics card = 450w). I will be at at least 6000W. Is all 208V 30A power called L14-30? I will be buying the PSU to accomodate the best power solution for my needs, I haven't acquired it yet.
 
Something tells me you do not have 208 volts available, but that probably doesn't matter too much to your equipment, as it probably all operates at 120 volts, but your selected PDU may or may not matter what the input actually is. My guess is this place is supplied by a 3 phase 4 wire delta system which will have 240 volts between phases, 120 to neutral/ground on two phases and a hi leg that is 208 volts to neutral/ground. You will not want to connect to this high leg with your 120 volt equipment or you will see smoke come out of some power supplies at the very least. I would suggest you consult with someone qualified and that knows about these kind of systems and have them install the receptacle for your equipment.
 
theduude said:
They aren't normal, some of them will have 3 7990s running(7990 graphics card = 450w). I will be at at least 6000W. Is all 208V 30A power called L14-30? I will be buying the PSU to accomodate the best power solution for my needs, I haven't acquired it yet.
Click to expand...


L14-30 is a NEMA standard locking plug. It is a 4 wire plug rated 30 amps and a voltage rating of 120/140 volts, meaning there are two "hots", a "neutral" and an equipment grounding conductor. You could connect it to anything you wish, including a 208/120 system, but what I mentioned is it's intended connection configuration.

Properly applied L14-30 plug could supply about 7200 watts, but if the load were continuous should probably be derated to at least 80% of that.
 
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JMHO
I'll go against the flow! Your going to need to get it engineered. There is so many questions
that I have, people get paid to ask them. It might be or even sound endless.

You might or might not have a lot of things! You don't just supply such basic requirements
of equipment with in a space for only this or for that! What ever your building codes are will
be more than what you've stating here!

For example; You have office space, either it is real walls or cubicles or blade partitions these need addressing for power. You might have bathrooms, you might have storage, you might have open free space, maybe the need for the Fire Alarm to updated because of your office types.

Either the electrician that you get involved or a professional should tell you the same there
to many combinations of some sorts that need to be brought up to Code for your space!

I've said this...You need to bring in some professionals!
 
Last edited:
cadpoint said:
JMHO
I'll go against the flow! Your going to need to get it engineered. There is so many questions
that I have, people get paid to ask them. It might be or even sound endless.

You might or might not have a lot of things! You don't just supply such basic requirements
of equipment with in a space for only this or for that! What ever your building codes are will
be more than what you've stating here!

For example; You have office space, either it is real walls or cubicles or blade partitions these need addressing for power. You might have bathrooms, you might have storage, you might have open free space, maybe the need for the Fire Alarm to updated because of your office types.

Either the electrician that you get involved or a professional should tell you the same there
to many combinations of some sorts that need to be brought up to Code for your space!

I've said this...You need to bring in some professionals!
Click to expand...
What needs decided that a journeyman isn't qualified to decide?

OP already has determined what equipment will be supplied, needs to know which PDU to select based on whether 208/120 or 120/240 is what is available. You saying only an engineer can tell the difference between these systems? Only other thing may be determining if there is enough capacity to handle the additional load, but it doesn't take an engineer to determine that either.
 
cadpoint said:
Either the electrician that you get involved or a professional should tell you the same there
to many combinations of some sorts that need to be brought up to Code for your space!

I've said this...You need to bring in some professionals!
Click to expand...

kwired said:
What needs decided that a journeyman isn't qualified to decide?
Click to expand...


I think that cadpoint is looking at the big picture as in opening the business and everything that may be needed to get a business license and be open to the public ( if that is what the OP is doing).


If a permit is needed and it probably is to run power from the panel to this office space then these problems can come up. In some areas you may need engineered drawing for any changes that you make to the building.

I would think that the easiest way to start would be to consult with a local licensed electrical contractor. He really needs to know for sure if he has 240V or 208 available before he starts to purchase equipment.
 
kwired said:
What needs decided that a journeyman isn't qualified to decide?

OP already has determined what equipment will be supplied, needs to know which PDU to select based on whether 208/120 or 120/240 is what is available. You saying only an engineer can tell the difference between these systems? Only other thing may be determining if there is enough capacity to handle the additional load, but it doesn't take an engineer to determine that either.
Click to expand...

growler said:
I think that cadpoint is looking at the big picture as in opening the business and everything that may be needed to get a business license and be open to the public ( if that is what the OP is doing).


If a permit is needed and it probably is to run power from the panel to this office space then these problems can come up. In some areas you may need engineered drawing for any changes that you make to the building.

I would think that the easiest way to start would be to consult with a local licensed electrical contractor. He really needs to know for sure if he has 240V or 208 available before he starts to purchase equipment.
Click to expand...

A good EC or Journeyman will know when to get more help envolved and my PE friend has mopped up many a time when they have had not gotten or given better advice.

A good EC or journeyman should know spacial requirements, other various codes that a can effect their client. In my area most rental upfit spaces get a fine comb over. Bathroomws get upgraded, type of applications get booted due to structure types.

So around here, yes it can be done by the correct EC or solo licensed person, but not without heavy review in my metro area.

Back to the OP, it seemed to me they only cared about their equipment when in fact more will be involved. It will take someone to determine the othe code spacial requirements that might need to be address and that all power is accounted for. Does it take an engineer no, could it yes, the OP isn't addressing these issues.

Yes KW, I understand your point, and yes it's fair to say. Thank you.
 
cadpoint said:
A good EC or Journeyman will know when to get more help envolved and my PE friend has mopped up many a time when they have had not gotten or given better advice.

A good EC or journeyman should know spacial requirements, other various codes that a can effect their client. In my area most rental upfit spaces get a fine comb over. Bathroomws get upgraded, type of applications get booted due to structure types.

So around here, yes it can be done by the correct EC or solo licensed person, but not without heavy review in my metro area.

Back to the OP, it seemed to me they only cared about their equipment when in fact more will be involved. It will take someone to determine the othe code spacial requirements that might need to be address and that all power is accounted for. Does it take an engineer no, could it yes, the OP isn't addressing these issues.

Yes KW, I understand your point, and yes it's fair to say. Thank you.
Click to expand...
I will have to admit that when I first replied I didn't consider that this may very well be a new occupant moving into a new space and may entail more than just connection of the computer equipment that the OP seems to be mostly concerned with.
 
theduude said:
I'm not an electrical engineer but I've been browsing the forums and it seems as though the people here are very knowledgeable. I am a computer repairman that has specific power needs. 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. Ok, so, mainly I need 6000-7000W of continuous power because 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?

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,jr...Gid,zcUMyBn,GjmgFvw,DyjAoWi,Bhx0o1E,CMNGwik#4
Click to expand...

sounds like a burn in rack.... so.... you have a delta service, so a 240 volt pdu is your best choice.
most pdu's will work with either voltage, but you can go use the high leg as one of your phases,
and so you may have a better chance of this working well for you. high legs are usually underutilized,
for the obvious reason.

you don't need our advice, you need a licensed electrician on site, with a data logging amp meter,
to see what your actual load on that three phase panel is. contact your landlord for whoever he uses.
with luck, it will be the same person who put all those panels in, and knows the building.

careful consideration of connected loads may prove that you can in fact pull a 30 amp load off a panel.

7kw is 3,500 watts per leg, balanced. or, 29 amps. it is a very poor practice to design something that
runs above 80% of the circuit capability. at least the code seems to feel that way.

so, you don't need a 7k pdu. you need more. how much more? well, the inverse of 80% is 1.25

so, add 25% to the test load, and go buy one that size, and supply it with a 40 amp circuit, or whatever
size circuit is appropriate for the connected load.
 
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