Article 220 table 220.86 How do I use this table?

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cwain

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I understand how to use table 220.42 for lighting load demand factors for dwelling units. First 3000va at 100% 3001-120000 at 35% and remainder over 120000 at 25%.

But on table 220.86 optional methed/schools- first (3va/ft2) at 100%, plus ( 3 to 20va/ft2) at 75%, plus remainder over (20va/ft2) at 25% . I dont understand how to apply this table. Please give me an example on how to use it? I looked in annex D and could not find one.
 
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cpal

Senior Member
Location
MA
cwain said:
I understand how to use table 220.42 for lighting load demand factors for dwelling units. First 3000va at 100% 3001-120000 at 35% and remainder over 120000 at 25%.

But on table 220.86 optional methed/schools- first (3va/ft2) at 100%, plus ( 3 to 20va/ft2) at 75%, plus remainder over (20va/ft2) at 25% . I dont understand how to apply this table. Please give me an example on how to use it? I looked in annex D and could not find one.
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this is out of the HB if the structure qualifies this is stepped demand factor is permitted.
Solution
The initial calculated load based on Table 220.86 is 1.5 mVA, or 1,500,000 VA.
1.15 mVA/100,000 ft2 = 11.5 VA/ft2
First 3 VA/ft2 at 100%:
3 VA ? 100,000 = 300 kVA
Remaining 8.5 VA at 75%:
8.5 VA ? 100,000 ? 0.75 = 637.5 kVA
Demand load for the school:
300 kVA + 637.5 kVA = 937.5 kVA
937,500 VA/1,500,000 VA = 0.82
or 82% overall demand factor on entire building load obtained using Table 220.86 demand factors.
 
C

cwain

Member
cpal said:
this is out of the HB if the structure qualifies this is stepped demand factor is permitted.
Solution
The initial calculated load based on Table 220.86 is 1.5 mVA, or 1,500,000 VA.
1.15 mVA/100,000 ft2 = 11.5 VA/ft2
First 3 VA/ft2 at 100%:
3 VA ? 100,000 = 300 kVA
Remaining 8.5 VA at 75%:
8.5 VA ? 100,000 ? 0.75 = 637.5 kVA
Demand load for the school:
300 kVA + 637.5 kVA = 937.5 kVA
937,500 VA/1,500,000 VA = 0.82
or 82% overall demand factor on entire building load obtained using Table 220.86 demand factors.
Click to expand...

I'm sorry but Im still lost . I guess its the dumb okie in me
 
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cwain

Member
Ok, I think I have this figured out. But I still dont know what (HB) is, or where you got 11.5va/ft2 x 100,000
 
C

cpal

Senior Member
Location
MA
cwain said:
I,m sorry cancel the 100,00. I meant where did the 11.5va/ft2 come from?
Click to expand...

The HB example divides the total load (gen ltg and connected appliances )by the sq footage. 1,500,000VA / 100,000 Sq Ft = 11.5 VA per Sq Ft.
 
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