Load Calc Office high rise

[electricbiddr]

Hello, I am calculating a load for a high rise floor approximately 22,000 square feet. I have calculated the lighting and receptacle load according to the 220.12 & 220.14. My results were extremely higher than the actual load readings. (we monitored the load for (1) week with current monitoring equipment.)
My question is that since the building has a separate system for HVAC and a separate system for EM lighting is there any deduction I can take for the reduction in load verses the calculated actual and square foot calc. which would take into consideration the fact that there are no heating or airconditioning loads on the service.
There are approximately 10,000 square feet occupied, 10,000 square feet vacant, and 7,000 square feet in elevator and common hallway space.
The service size is 800amps 120/208v
The actual current monitoring came up with an average of 115Aac per phase.
The calculated total load came up with 123kva total for lighting and receptacle load. Which is substantialy higher than the actual.
22,000 X 4.5w/sq ft = 99kva
323 each receptacle straps x 180va = 58,140va
10,000 100% demand
48,140va x 50% = 24,070va
99kva + 24kva = 123kva
We are going to submit this to the City for a proposal to add a 350A 3-meter fitting to subdivide existing tenant space.
I belive they will deny me based on the calculated load. But the actual load shows it is feasible.

 

[bob]

My results were extremely higher than the actual load readings. (we monitored the load for (1) week with current monitoring equipment.)

Where did you monitor this load?
220.12 requires that table 220.12 is the minimum lightning load.

The calculated total load came up with 123kva total for lighting and receptacle load. Which is substantialy higher than the actual.
22,000 X 4.5w/sq ft = 99kva
323 each receptacle straps x 180va = 58,140va

Table 220.12 uses 3.5 va per sq ft. You are using 4.5 va per sq. ft.
Did you add the 1 va for receptacles?

22000 x 3.5 = 77000 va
323 rec x 180 = 58140
total = 135140 va

10000 x 100% = 10000
48140 x 50% = 24070
Total = 34070
LTS = 77000
total = 110070 va = 306 amps per phase.

 

[electricbiddr]

Thanks for the calculations. It seems I had calculated the lighting at 4.5w/sq ft instead of 3.5w/sq ft based on the fact that I knew the number of receptacles for the floor.
If I go to the City with the actual load findings verses the calculated load findings will they accept our findings? Or do they go on the basis of the calculated load only?
Tom

 

[bob]

I think they will hold you to the 77 kva of lightning load. As I said
220.12 requires that table 220.12 be used to determine the minimum lightning load.

The service size is 800amps 120/208v

I know you have not shown all the load but at this point you are a long way from an 800 amp service. Maybe a 600 amp if the A/C and heating are on another service.

 

[electricbiddr]

Thanks for the info Bob, what did you mean by maybe a 600amp if the A/C and heating are on another service?

 

[bob]

In your origional post you said

My question is that since the building has a separate system for HVAC and a separate system for EM lighting is there any deduction I can take for the reduction in load verses .....

. The caculated load at this point is 306 amps. I know there is additional load but the service may be only 600 amps instead of 800 amps.