Existing Demand and New Addition

[Shoe]

I have an existing building (refrigerated warehouse) that uses about 200A maximum demand on a 1200A service over the range of many years. They are doubling the size of the building with more refrigeration space (exact-same systems and use).

I know I can use existing demand data to prescribe the load for the existing building (+125%). However, if I calculate the new loads per NEC, I exceed 1200 amp service for the addition.

Because use is exactly the same, it's fair to say that their new demand will be about double their existing demand and fit in their existing service (so about 400A max demand).

I feel silly telling the client that they need to add another service for this building (existing service can't be upgraded), when I know the existing service will work.

Is there anything that would allow me to take historical demand as a factor into new construction? Or am I stuck delivering the bad news?

 

[charlie b]

If the new addition will have the same square footage, the same lights, the same refrigeration equipment, the same office and conference space, the same break room equipment, and the rest, then I would accept using the existing data as the basis for calculating the load on the new space. I would say it is worth bringing this approach to the AHJ.

 

[Shoe]

Good suggestion. I will review with the AHJ.