Multifamily calculation check

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crtemp

crtemp

Senior Member
Location
Wa state
I haven't done one of these in quite some time. Just hoping someone can take a quick look at my procedure and see if I left anything out or did something wrong.
The units are town homes and have gas furnaces, gas ranges, and will not get air conditioners.

5 plex individual square footage

1358

1471

1580

1580

1646

7635 – Total square footage



Small appliance branch circuits

1500 * 10 = 15000



Laundry load

1500 * 5 = 7500



Total general lighting 30135

First 3000 @ 100% 27135 @ 35% = 12497



Clothes dryers

5000 * 5 = 25000

25000 @ 85% = 21250







Appliances fastened in place

Dishwasher 960 * 5 = 4800

Disposal 600 * 5 = 3000

Water Heater 4500 * 5 = 22500

Total 30300

30300 @ 75% = 22725





Micro hood

1000 * 5 = 5000



Gas Furnace

1800 * 5 = 9000





Total

12497 General lighting

21250 Clothes dryers

22725 Fixed appliances

5000 Microwaves

9000 Gas furnaces



70472 / 240 = 294 amps

Will install two runs of 4/0 to meter pack
Will install 4/0 SER with 200 amp breaker to each individual unit. Will install main lug 200 amp panel in each unit
 
"and will not get air conditioners "
Never had a residential unit with AC.

Appliances Fastened in place...does it not say each unit must have 4 or more to take advantage of the 75% ?

Have you calculated each unit individually ? Most likely you will not need 200A to each unit.
 
Now that I read 220.53 closer you are correct. I'll have to take that part out. As for the 200 amp service to each unit, this is what the builder has spec'd out.
With the 75% fix I'm coming up with 325 amps for the service. I think I'm still good with 2 runs of 4/0 to the meter pack
 
crtemp said:
Now that I read 220.53 closer you are correct. I'll have to take that part out. As for the 200 amp service to each unit, this is what the builder has spec'd out.
With the 75% fix I'm coming up with 325 amps for the service. I think I'm still good with 2 runs of 4/0 to the meter pack
Click to expand...

Your lighting number is wrong. You didn't multiply the square footage times 3va.

There is certainly more than four appliances fastened in place. You had 15.
 
Last edited:
david luchini said:
Looks to me like the optional method in 220.84 would keep the load below 300A.
Click to expand...
what about 220.84(1) and (3)? The units don't have electric cooking equipment (unless you count the microwave) and they don't have electric heat (gas furnace, again unless you count the fan on the furnace)
 
crtemp said:
what about 220.84(1) and (3)? The units don't have electric cooking equipment (unless you count the microwave) and they don't have electric heat (gas furnace, again unless you count the fan on the furnace)
Click to expand...
You're correct. I overlooked that you said no air conditioning.
 
"As for the 200 amp service to each unit, this is what the builder has spec'd out"
If they are planning for future connect capacity where EACH townhome could have 200A of connected load...car chargers, hot tubs, etc. it can not happen going down this road.
 
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