# Multifamily dwelling load calc



## CopperSlave (Feb 9, 2012)

Lighting- 3va x 1050 x 4 units= 12,600

Small appliance & laundry= 4,500 x 4= 18,000

Fridge 1500 x 4= 6,000
Dishwasher 1500 x 4= 6,000
Water heater 4500 x 4= 18,000
Microwave 1500 x 4= 6,000
Range 8000 x 4= 32,000
Dryer 5000 x 4= 20,000
_______________________________
118,600 va x 45%= 53,370va

53,370/240v= 222.375A

Used the optional method. Now, somebody needs to check MY math.:jester:


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## ray_rodriguez15 (Jan 12, 2013)

Thank you sir


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## bml215 (Jul 2, 2012)

ray_rodriguez15 said:


> Can someone double check my math and code application.
> 
> Doing a load calc for a single service feeding 4 small apartment.
> 
> ...



1050 x 3va = 3150
Small appliance + laundry = 4500
Total = 7650 - 3000 = 4650 @ 35% = 1627.5 
1628 + 3000 = 4628 for GL

GL 4628
Fridge 1500
DW 1500
WH 4500
Mwav 1500
ScH 2400
Range 8000
DRY 5000
Hpump 11000

Total 40028

40028 / 240 = 166.78a


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## te12co2w (Jun 3, 2007)

Keep going. It will be down to 100a service pretty soon.


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## LGLS (Nov 10, 2007)

HOW is the fridge 1500 w? That isn't a load calc, that's a freakin' guess.


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## ray_rodriguez15 (Jan 12, 2013)

*Fridge*

I listed the fridge st 1500 va due to the fact ive yet to see one above 12-13 amps and its dedicated instead of on the 2 sabc


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## bml215 (Jul 2, 2012)

Throw a 200 in each of em and you'll be fine.


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## bostongtp (Apr 9, 2014)

IslandGuy said:


> HOW is the fridge 1500 w? That isn't a load calc, that's a freakin' guess.


Lol... What kind of fridges do they have on the islands?? Do you think he should ask the GC EXACT models of the fridges, toaster, dishwasher, etc being installed?? No, because no ones knows yet. Your correct in one thing, the fridge isn't a load calc, it's apart of the load calc. We use generic values for various appliances, clothes dryers, cooking, etc. to get an idea of what we're going to need. For residential, I'll list some common values below.

Examples:
- Clothes Dryers/5400va
- Heat/5000va
- water heater/4500va
- disposal/900va

Hope this helps Island guy.


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## ray_rodriguez15 (Jan 12, 2013)

*Meter bank*

That is the plan i was needing help on the single service coming in hitting a 4 pak meter bank and having 200 amp breakers feeding each units main panel.


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## ray_rodriguez15 (Jan 12, 2013)

What the hellnis a house load? !!!! Art 220.84(b)


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## bml215 (Jul 2, 2012)

ray_rodriguez15 said:


> What the hellnis a house load? !!!! Art 220.84(b)


The load calc of the home....


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## ray_rodriguez15 (Jan 12, 2013)

*220.84(b)?*

Maybe im having a brain fart, but in still confused at the article section. " house loads shall be calculated in accordance with part III of this article and dhall be in addition to the dweliing losds calculated in accordance eith table 220.84." What does this mean? What is the difference between dwelling unit load house loads?


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## bml215 (Jul 2, 2012)

ray_rodriguez15 said:


> Maybe im having a brain fart, but in still confused at the article section. " house loads shall be calculated in accordance with part III of this article and dhall be in addition to the dweliing losds calculated in accordance eith table 220.84." What does this mean? What is the difference between dwelling unit load house loads?


My guess:

House load is the load of all 4 dwelling units together where the dwelling unit load are single, which I guess you factor at the 45% demand factor when sizing the service


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## bml215 (Jul 2, 2012)

bml215 said:


> My guess:
> 
> House load is the load of all 4 dwelling units together where the dwelling unit load are single, which I guess you factor at the 45% demand factor when sizing the service


ETA: I closed my book already but I think they said this is optional.


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## ray_rodriguez15 (Jan 12, 2013)

*......*

Thanks i think im grasping it, but ill digg a little deeper


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## bml215 (Jul 2, 2012)

Sometime 5 minutes away from that book will make a big difference. I'm waiting for someone else to chime in on that last question though; I may be wrong, but that is my interpretation.


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## bostongtp (Apr 9, 2014)

ray_rodriguez15 said:


> Thanks i think im grasping it, but ill digg a little deeper


Look all the way in the back of the NEC in the annex, I think it's D (4)? It shows you examples of calculating Multi - Family service feeders.


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## T&K (Jun 18, 2012)

Typically the "house load" is referring to the loads that are not specific to a certain dwelling. For example, a common hallway, exterior lighting, sprinkler systems, fire alarm systems, etc.


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