School lighting load calculation

[Trep21]

How do I calculate the overall load for a 100,000 sq.ft. school, using T 220.86, assuming that the initial calculated load was 1,500,000 VA.

 

[david luchini]

3va/sf @ 100% = 300,000va
12va/sf @ 75% = 900,000va

Demand load - 1,200,000va

 

[paullmullen]

 

[paullmullen]

Amazing when two people in this forum come to the same conclusion.

 

[Trep21]

3va/sf @ 100% = 300,000va
12va/sf @ 75% = 900,000va

Demand load - 1,200,000va

I understand the 3va/sf @ 100%
But how did you come up with the 12va?

 

[david luchini]

I understand the 3va/sf @ 100%
But how did you come up with the 12va?

15va/sf - 3va/sf = 12va/sf

 

[Elect117]

1,500,000/100,000 = 15 VA / sft

from table 220.86:
first 3 @100 %
between 3 and 20 VA/sft @75%

So 15-3 = 12 for the between 3 through 20VA/sft part of the table

3VA/sft * 1 + 12VA/sft * .75 = 3 + 9 = 12 VA/ sft

then multiply the sqf back in -> 12*100,000 = 1,200,000 VA (or 1.2 MVA)

 

[Trep21]

15va/sf - 3va/sf = 12va/sf

Thank you for the help!

 

[david luchini]

The overall load for a 100,000 sq.ft. school, with an initial calculated load of 1,500,000 VA and applying the demand factors from NEC Table 220.86, is 630,000 VA.

630,000 VA is wrong. I'm curious how you came up with that number.

 

[Trep21]

The overall load for a 100,000 sq.ft. school, with an initial calculated load of 1,500,000 VA and applying the demand factors from NEC Table 220.86, is 630,000 VA.

How did you come up with that?