what a waste

[jrvazzer]

Gentlemen, Here is a problem that seem to happen and keeps happening more and more . Sorry for repeating my self. I have a 400amp 480/277v distribution panel serving each office floor. each floor has approx. 54,000sf. The tenant moves in and takes up 37,000 sq. ft. and at 7 watt per sq. ft. he is entitle to 265amps. However because he as a small data center with redunant UPS and CRAC units they require in the 400A panel (2) 150A, (2) 50
A, (1)175A for XFMR ,100A for Lighting and 40A for TVSs all 3pole.
Now this is the issue. There is still 17,000 sq. ft for the next tenant remaining. The 400A panel is total out with all the breakers install. 9 month after the tenant has moved in, the next tenant is looking for 225A. Where do we get it from. Checking the load meter for the existing tenant his highest peak for the year including Summer loads was no higher than 3 Watt per sq. ft. Do I tap into the same 400A panel . Tha existing tenant has not even come close to using his power potential
This is happening in many facility where consulting engineers require all this power only to see them actually use a fraction of the load and costing the owner more ether in bring in a new riser or modifying the existing serve.

 

[brian john]

You base what you need on what is being used if there is spare capcity, then there is no problem.

Install a power monitor for 30 days or check any billing data you may have for the existing tenant.

 

[peter d]

That is why utilities will undersize transformers and service drops from NEC required sizes. They know better.

 

[john_axelson]

What is the lease agreement with the existing tenant? Were they guaranteed a certain watts per square foot in their lease? When they came in with the Data Center, why didn't the landlord make them pull up the "additional" ampacity from the basement, thus leaving the "shared" panel for future tenants?

I don't blame the engineer in this instance, just because the tenant with the Data Center may get over 50 w/square foot eventually, then what do you do, your "shared" panel becomes over loaded and two tenants get upset.

I don't know which viewpoint you are representing (installing contractor, land lord,etc.) but in this case I would plan that the tenant that wants the 17,000 square feet needs to bring up a new service to the space with the land lord incurring the cost for this, if the lease agreement stipulates so many watts per square foot.

 

[Jomaul]

What I would have done would be to do a load calc on the first tenant prior to installing any wiring. That would tell me exactly what my load is and then wire accordingly.He may have needed all 400 amps and without a load calc you can't make that determination. On the second tenant you again need to do a load calc to determine there service requirements. It seems to me the only way to determine if 400amps can service both tenants.

 

[boater bill]

A couple of things to consider:
A 225 amp subpanel from the exiting 400 amp panel would work... If the building uses common metering. If the 2 tenants have seperate metering then you would need a seperate feed. If there are no more breaker spaces available in the 400 amp panel, relocate 3 cisrcuits to the new sub-panel to feed it.

Good luck!

 

[mayanees]

.... data center

.... data center

jrv,
You said the magic word when you said data center.
The need for so many circuits comes from the nature of the design. Each circuit is backed by another circuit, which is backed by another circuit.
So any one circuit is never loaded over 50 %, so it can accommodate a another failed circuit and not be overloaded.
I see designs where the total critical power load that the raised floor space is designed for (in UPS kW) is distributed over so many 120V circuits that the average amperage per circuit is on the order of 3-5 amps.
.. nature of the beast!
JM

 

[Mr. Bill]

Correct me if I misinterpret any of your information

Max of 3W per sf * 37,000 sf / 277V / 3 = 133.5A of measured demand.

Existing demand (133.5A) * 125% + new load (17,000sf space) = new load on panel. Sounds like you have spare ampacity for the new tenant.

(3) 6-inch breakers + (4) 4.5-inch breakers = 36 inches of breaker space used.

I think you meant that there is no available physical breaker space when you said, "The 400A panel is total out with all the breakers install." To solve this problem on future projects you should have panels with 45 or 63 inches of breaker mounting space.

A typical 2N data center design will use about 30% or less of each UPS's capacity.

 

[jrvazzer]

Yes, your correct their is no space for a 225A c/b.

 

[Mr. Bill]

Then I like boater bill's solution to the current situation.

 

[LawnGuyLandSparky]

Gentlemen, Here is a problem that seem to happen and keeps happening more and more . Sorry for repeating my self. I have a 400amp 480/277v distribution panel serving each office floor. each floor has approx. 54,000sf. The tenant moves in and takes up 37,000 sq. ft. and at 7 watt per sq. ft. he is entitle to 265amps. However because he as a small data center with redunant UPS and CRAC units they require in the 400A panel (2) 150A, (2) 50
A, (1)175A for XFMR ,100A for Lighting and 40A for TVSs all 3pole.
Now this is the issue. There is still 17,000 sq. ft for the next tenant remaining. The 400A panel is total out with all the breakers install. 9 month after the tenant has moved in, the next tenant is looking for 225A. Where do we get it from. Checking the load meter for the existing tenant his highest peak for the year including Summer loads was no higher than 3 Watt per sq. ft. Do I tap into the same 400A panel . Tha existing tenant has not even come close to using his power potential
This is happening in many facility where consulting engineers require all this power only to see them actually use a fraction of the load and costing the owner more ether in bring in a new riser or modifying the existing serve.

They've commondeered 100% of the panel space w/o leasing 100% of the floor space. Lease should have prevented it. Remove the 3P TVSS and hand it to them, tell them to install it in their own panel space.

Add your 225a breaker there.

 

[hector pe]

what a waste

I also agree with Boaterbill solution. It is a practical manner we've utilized to solved that problem with sub-panels.

hector pe