Existing Load Calculation 220.87 NEC with utility bills.

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VENgineer

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Miramar Fl
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Electrical Engineer

How to translate 1 year data from POCO to peak demand for 220.87 calculation​


Thank you in advance. I'm trying to determine which demand value I should use for the calculation. If you could help clarify: I've attached an image from a month of the electricity company. I understand that I should take the maximum value over the last 12 months, but I'm confused about which value to use. Afterward, I need to divide it by a conservative power factor (0.8) and then add 25% to determine the reserve I can use for the new load.




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Thanks so my next qs is this one:
Based by the maximum demand 4557KW,
4557KW / (480V*1.73) = 5487A (And I am not taking into account the power factor, which would increase the result)

The disconnect associated on this service is 4000A, and never have any issue. How is this possible?
 
Are you sure that this is the only service on the site? Is the meter on the primary side of the utility and they may have two services?
I would also call the utility and see if you can get maybe better information from them.
 
Knightryder12 said:
Are you sure that this is the only service on the site? Is the meter on the primary side of the utility and they may have two services?
I would also call the utility and see if you can get maybe better information from them.
Click to expand...
They have 6 services (4000A e/o) but that utility bill is from one of the 6s meters.!!
This one is the riser diagram where shows 4000A disconnect!


Captura de pantalla 2023-11-17 132028.jpg
 
They averaged 89,000 kWh a day - that's an average kW of 3708 kW. So the 4557 kW peak demand seems realistic. I agree that you should discuss with the utility. If there are six services like this one, their utility bill is in the neighborhood of $1 million/mo. Utility should be happy to help.
 
That peak is about a 128% overload. I can see the main device being able to carry that load for the 15 minutes it would take it to be captured.
Then the question is what caused this peak?
 
With this amount of usage and demand, I would definitely work with the customer to get access to a year's worth of interval data. It would give you the detailed usage profile. I don't know what your role/goal is here, but there is potentially a lot of energy costs to be saved.
 
AlaskaElectric said:
They have 6 services (4000A e/o) but that utility bill is from one of the 6s meters.!!
This one is the riser diagram where shows 4000A disconnect!


View attachment 2568598
Click to expand...
With this many services, again are you sure they are not primary metered? I do not see the metering at all on this diagram, unless I am missing it.
 
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