Dwelling Service Load Calculations

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FlyWhale

FlyWhale

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Location
NC
Occupation
Electrician
I'm stumped on this load calculation. I can't seem to figure it out.

A single family dwelling is supplied by a 120/240v, single phase service. The dwelling has 2500 square feet and the following:

10,000 VA fixed space heater at 240v
11,000 VA range at 240v
4,500 VA clothes dryer at 240v
800 VA disposal motor at 120v
Two non-motor, 120v, not fastened in places appliances, with a total combined nameplate rating of 2,500 VA.

What would be the total minimum load using the standard method?
 
Little Bill said:
Can you show us your work and how you figured it, and maybe we can direct you from there?
Click to expand...


I'm on mobile so I'll do my best

2,500 ft² x 3VA/ft² = 7500VA. Per 220.12

10,000 VA fixed space heater @ 100%. Per 220.51

11,000 VA range turns to 8 kW per table 220.55
Also to mention kVA shall be considered equivalent to kW in 220.55
So...8000VA?

4,500 VA clothes dryer turns to 5000 VA. Per 220.54

The 2 non-motor appliances at 2,500 VA

800 VA x 1.25 = 1,000 VA per 220.50 which took me to 430.24 (1)

7,500 general Lighting Loads
10,000 fixed space heater
8,000 range
5,000 clothes dryer
1,000 disposal motor
2,500 non-motor appliances
3,000 (1,500 x 2) per 220.52 (a)
1,500 per 220.52 (b)

Using the example in Annex D...
7,500 + 3,000 ( 220.52 (a)) + 1,500 ( 220.52 (b)) + 10,000 + 1,000 + 2,500

= 25,500

3,000 VA @ 100% per table 220.42
25,500 VA - 3,000 VA = 22,500 @ 35% = 7,875

7,875 + 8,000 + 5,000 = 20,875 VA

20,875 is not what I'm supposed to get.... it's supposed to be 32,650 VA.
 
2500x3=7500
7500
3000SA
1500LA
=12000va
12000
-3000
=9000
x0.35
3150va
+3000
=6150GL
(6150GL + 5000dryer + 8000range + 1000disp. + 2500va 10000heat)=32650VA
 
Dell3c said:
2500x3=7500
7500
3000SA
1500LA
=12000va
12000
-3000
=9000
x0.35
3150va
+3000
=6150GL
(6150GL + 5000dryer + 8000range + 1000disp. + 2500va 10000heat)=32650VA
Click to expand...
I see.... can you explain why they are added in that specific fashion?
 
Table 220.42 Dwelling units..
220.52 Small Appliance & Laundry " The Last sentence" : These loads shall shall be permitted to be included in the general lighting load and subjected to the demand factors provided in Table 220.42
 
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