Another Stupid Question part 3

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lady sparks lover

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My new boss, yes I said new, has a this new standard. Any building under 100,00 square feet should be 208V. Does this sound reasonable?

it sounds expensive....


Lady :)

[ August 10, 2005, 05:54 PM: Message edited by: lady sparks lover ]
 
Re: Another Stupid Question part 3

I think that it would depend more on the load than the size of the building. As I remember the old standard from years ago was 500 Kva. Above that load it became more economical to use 277/480 and transformers for 120/208. Below that level 120/208 was cheaper.
 
Re: Another Stupid Question part 3

What about a 30 x 40 pump station with 3 75 hp motors? Not practible at 208.
 
Re: Another Stupid Question part 3

I was just working on a 85,000 square foot data center, which was designed for approx 8MW of capacity. It would be tough to do that @ 208V, so we went with 13,200V, and stepped down as needed.
So it depends on the load.
 
Re: Another Stupid Question part 3

the place I used to work had 240 3 phase service with transformers the size of a small car to make 480 that everything actually ran on.

it was that much cheaper to put in 240 versus 480 when they built the building.

No logic to it at all.

The building I now work in has 208 service with some small 208/480V xfmrs to handle the small 480V loads we have.
 
Re: Another Stupid Question part 3

Originally posted by lady sparks lover: Any building under 100,00 square feet should be 208V.
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Something of this nature might make for a good "rule of thumb," a good starting point for the design process. But every case must stand on its own merit.

You need to be thinking about more than cost. What type of facility are you building? What is the total calculated load? What types of equipment will it contain? How sensitive is that equipment to voltage dips that might occur when large motors (perhaps even elevator motors) are started? How tolerant will the facility be to power interruptions? Will the facility have a back-up, on-site power source? A factory, a medical office, and a computer data center might all have the same area, but different power needs.

By the way, did you mean 10,000 or 100,000?
 
Re: Another Stupid Question part 3

I agree with Charlie with a caveat. The serving electric utility will sometimes dictate what it will permit you to have. If you came to me with you requirements, I would determine if you could have the voltage you wanted (Actually Lady, I would let you have anything you wanted :D ). We will look at the types of loads, the proximity of other customers, what we believe your demand will be, etc. to decide if you can have the type of voltage configuration you desired.

Assume you have a building that is close to a property line and we can serve it with a 300 kVA transformer. We may elect to install a 500 kVA in order to serve this building and the one next door when it is built. At this point, we would tell you that 208Y/120 is the only voltage configuration that is available. :D
 
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