Article 220.87 Determining Existing Loads

[s1msgroup]

We do both prototype design and site adapt of prototypes. Once prototypes are built and actual historical data is available on maximum demand, can you use 220.87 to calculate service load for new sites?

Original main distribution panels were sized in accordance with NEC. However, with load changes, the MDP's should be larger (1200A vs 1000A) along with service feeder.

However, there is a significant amount of historical data to indicate this is not required. Actual peak load less than 1/3 of calculated demand load.

 

[Ragin Cajun]

Sounds like you're good to go. Add the new demand to the existing and make sure it's withing the service capacity.

I have done numerous "upgrades" this way.

Never had to increase service size, at least for foor service. Now industrial jobs, that's another matter.

 

[bob]

I was wondering what kind of loads you are installing since the demand is only 1/3 of the caculated demand.

 

[don_resqcapt19]

s1msgroup,
I don't see how you can use 220.87 on a prototype installation and apply that to other installations. 220.87 is only used to arrive at the existing load at an existing installation. While is would be very logical to use the demand and load information from a prototype and apply that information to the same prototype build in another location, I don't see any support for that in the NEC.
Don