Service size for 2000 amps

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Harry C

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I'm in the process of starting a new job that part of it is installing a new 2000 amp service and . The service will supply all the hvac loads that are being taken out and upgraded including 2 new chillers. The drawings call for 6 sets of 4 - 750 mcm to feed this new 2000 amp service. This seems like a large over kill . By looking at it it looks like I should be able to use 6 sets of 4-500 mcm to feed this. Am I correct in this assumption? I'm trying to get away from using the 750mcm if I can. It is to much of a pain to use 750 and also a greater cost to the customer if they don't need it.
 
If the drawings call for 6 sets of 750s, that what should have been bid. The EE may have reason to design it that way.

You can always ask about it. You may be able to 'save the day' and do some value engineering for the customer. It's worth looking in to.
 
How is this set of conductors to be routed (i.e., from where to where, what distance, and is it to be in a concrete-encased, underground, duct bank)? Also, is this set actually a "service," directly from the utility transformer, or is it a feeder from a customer-owned switchboard?
 
It's actually a service. It comes directly out of the power companies transformer. The total distance from the trans. to the switchboard is approximately 90 ft away. They will be routed under ground incased in concrete from the trans to the building which is 60 ft away then go up the side of the building and into the gear which is about 30ft.
 
Harry, I agree with you, 6 sets of 750's times the lowest ampere rating ( 400a ) still is

2400a. Then, 6 sets of 500's x 380a = 2280a so you're still on the strong side. I'm seeing

more and more of this type of problem, sign of the times.
 
I'm just wanting to make sure my customer is getting the best bang for the buck but I don't see it with there design here. I could see it if the gear was rated for more than 2000 amps Then they could upsize it in the future. Also I don't want to wrestle that 750mcm through a 4 inch LB if I don't have too.
 
Threadstarter is right, not really sure why this was designed this way. No significant voltage drop to consider, using 500 KCMIL seems to be the way to go. I do think you can give the engineer a call and see what was the rational, let me know as I am interested.
 
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