Existing Load on the house panel

[Eclectic engineer]

Hello,
Based on past 12 months of utility bills, the peak demand on the house meter in a multi-family building is 25 kW. The house panel is rated at 400A 3ph 120/208V.
I am looking to calculate the existing amps on the house panel.

I am using the following formula - (25*1000)/(1.732*208*0.95) = 73A
1.25*73 = 91A

1.Is this the right formula? Any input about the power factor?
2. Available capacity on the house panel is 400A - 91A = 309A. Is this the right calculation?

Thank you.

 

[Eclectic engineer]

Any input on this?

 

[ptonsparky]

1. Multifamily residential, I wouldn't worry about PF at all.
2. Depending on the loads, I certainly wouldn't add 300 amps to a 400 amp panel that already has a peak load of 73.

 

[hbiss]

A house panel should be fairly consistent. Just measure it when all lights, etc are on.

-Hal

 

[Eclectic engineer]

1. Multifamily residential, I wouldn't worry about PF at all.
2. Depending on the loads, I certainly wouldn't add 300 amps to a 400 amp panel that already has a peak load of 73.

Can you share more information on this? Is there a NEC requirement that restricts maximum electrical load on a panel?

 

[ptonsparky]

More what I've always done. Limit load to 80% or less of CB. Based on a continuous load. Almost never will that occur with a calculated load, but IDK what your small details are.

 

[augie47]

Your calculation is basically correct. Being a house panel some, or all, the load might be continuous (hallway, site lighting).
You don't know how balanced the load is and you have not given the nature of the new load but I would agree with Post #3 and not depend on 300 amps being available pending further study.
215.2 & 230.42 show load limitations.