Calculating total amps to size panel using data

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Tainted said:
I'm almost 90% sure that the building might not have the available electrical infrastructure to handle that much power. It's a residential condo building.
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Yeah utilities don't like any extra capacity in their transformers as thats losses for them. So I doubt you'll find an extra 750kVA.
I have seen large campus buildings bring that in 4160V for chillers.
 
tortuga said:
Yeah utilities don't like any extra capacity in their transformers as thats losses for them. So I doubt you'll find an extra 750kVA.
I have seen large campus buildings bring that in 4160V for chillers.
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How likely do you think they would agree to bring me in a new 480V service for this much load? I mean they will be making a lot of money out of this since they will be selling the building a lot more electricity. So wouldn't they benefit from this actually? Also the utility company will most likely not pay for the new service and it would most likely come out of the building's pocket.
 
Tainted said:
How likely do you think they would agree to bring me in a new 480V service for this much load? I mean they will be making a lot of money out of this since they will be selling the building a lot more electricity. So wouldn't they benefit from this actually? Also the utility company will most likely not pay for the new service and it would most likely come out of the building's pocket.
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Yeah it's hard to say as utility costs can be all over the place, but from my experience yeah, a second service is going to be on your dime. I did a second 1200 amp 480 service once, utility used a 500 KVA pad mount transformer. It was about $16,000. Another time I did a second 200 amp 480 service, power company used 3x166 pole transformers (long story, they oversized the bank up to 3x75's due to a large motor, but then were out of those units so they upgraded us to 166's for free) and that was actually pretty much the same cost as the other one, 16.5k.
 
Tainted said:
How likely do you think they would agree to bring me in a new 480V service for this much load?
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The campus building that had 4160V (not 480) for chillers and was part of a huge upgrade, I would not have any idea on cost.
Around here the utility makes the customer pay for the transformer upgrades.
I have also seen 2400V chillers but that was many years ago.
 
jim dungar said:
Manufacturers follow different rules than what is found in the NEC.
There is no need for you to know what goes into their MCA and MOP numbers. If you really want to know, you would need to look into the product standards.
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Actually the product standard requires exactly the same thing that the NEC requires in 440.22.
 
don_resqcapt19 said:
Actually the product standard requires exactly the same thing that the NEC requires in 440.22.
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Then how is the nameplate data in the OP possible? Perhaps there are some different rules for inverter driven compressors; if that is covered in 440.22, I missed it.

Cheers, Wayne
 
wwhitney said:
Then how is the nameplate data in the OP possible? Perhaps there are some different rules for inverter driven compressors; if that is covered in 440.22, I missed it.

Cheers, Wayne
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They don't have to set it at the maximum permitted by either the code or the product standard...it is just a maximum size OCPD. They can set it at any value that permits their equipment to work.
 
don_resqcapt19 said:
Actually the product standard requires exactly the same thing that the NEC requires in 440.22.
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Keep in mind there is no requirement for HVAC chillers like this to be listed.
large chiller systems are complex and are typically an assembly of recognized parts.
Since the NEC covers motors well enough there is no need to have a different standard and another listing.
don_resqcapt19 said:
They can set it at any value that permits their equipment to work.
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As long as they dont exceed the code maximum.
 
tortuga said:
Keep in mind there is no requirement for HVAC chillers like this to be listed.
large chiller systems are complex and are typically an assembly of recognized parts.
Since the NEC covers motors well enough there is no need to have a different standard and another listing.

As long as they dont exceed the code maximum.
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Hermetic motor compressors were covered by Article 430 until the 1971 code when Article 440 was added to address hermetic motor compressors better that what was in Article 440.
The substantiation for the new article was:
The intent of this proposal is to provide a readily located source of reference in the National Electrical Code to cover the requirements for electric motor-driven air conditioning and refrigerating equipment and in particular the requirements for scale~ (hermetic type) motor compressors. The requirements now appear in various Sections in the National Electrical Code mixed in with requirements for other equipment and a separate article as proposed here should aid to clarify the intent and application of these requirements. Installations for central residential unitary air conditioning systems alone in 1969 will number 1,100,000 units. This does not include the additional millions of tons of air conditioning and refrigerating equipment installed in commercial and industrial applications. The basic need for this separate Article is to spell out the requirements of branch-circuit selection and protection for this class of equipment and to update the requirements as requested several years ago by inspection and approval authority.
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Great info thanks Don,
I was merely pointing out that 440 does not have a blanket listing requirement, like they did to lighting in 410 (which is a nightmare)
These types of HVAC systems often mix and match components and HVAC installers have at least 2 other codes to deal with.
The last 5-10 years there was a trend going around the CMP's to require every thing down to a ziptie to be 'listed' which I think just paints installers into a corner, is a deterrent to common sense, and breeds fake UL hologram stickers.
 
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