General Lighting Load

[migz87]

Im having trouble with this question . on the 2017 NEC. i did the calculations but this online test says the answer is 51,300 VA but im not gettin that . where am i going wrong ?

“Each unit of a 20-unit apartment building is 990 sq ft.
What is the calculated load for the general lighting,
and small-appliance and laundry loads for the
building?”

a. 51,300 VA
b. 74.700 VA
c. 105.600 VA
d. 149,400 VA

 

[charlie b]

Can you show us the steps that you tried? We generally like to see a member's failed attempt, so that we can point out where it went astray.

 

[migz87]

990sq ft x 20 units = 19,800 sq ft
x 3va
=59,400 VA Lighting ld
laundry -1,500 va per unit = 30,000 va
small appliance - 1500 va per unit= 30,000 va
( nec 2017 - 220.12 & 220.42)
now my question is where does the demand factor get involved in this calculation?

 

[HEYDOG]

990sq ft x 20 units = 19,800 sq ft
x 3va
=59,400 VA Lighting ld
laundry -1,500 va per unit = 30,000 va
small appliance - 1500 va per unit= 30,000 va
( nec 2017 - 220.12 & 220.42)
now my question is where does the demand factor get involved in this calculation?

You need a minimum of two small appliance circuits for each unit!

 

[migz87]

ok so its 60,000 va in building but it still doesn’t add up

 

[migz87]

2 small appliance circuit loads in 20 units = 60,000 VA
1 laundry circuit load in 20 units = 30,000 va
3va x 19,800 ( 990 sq ft x 20 units)=59,400 va

 

[curt swartz]

2 small appliance circuit loads in 20 units = 60,000 VA
1 laundry circuit load in 20 units = 30,000 va
3va x 19,800 ( 990 sq ft x 20 units)=59,400 va

You posted where to look 220.42

 

[HEYDOG]

2 small appliance circuit loads in 20 units = 60,000 VA
1 laundry circuit load in 20 units = 30,000 va
3va x 19,800 ( 990 sq ft x 20 units)=59,400 va

Laundry 1500 * 20 = 30,000
small appliances 2 * 1500 * 20 = 60,000
lighting 990 * 3 va * 20 = 59,400
Total = 149, 400

Table 220.42 Dwelling units first 3,000 @ 100% = 3,000.
149,400 - 3,000 = 146,400 next 117,000 @ 35% = 40,950
146,000 - 117,000 = 29,400 remaining over 120,000 @ 25% 29,400 @ 25% = 7,350

3,000
+ 40,950
+ 7,350
= 51,300