Load calculations on multi-family

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lightitup

Member
Location
Minnesota
A customer has a four plex apartment building and wants to replace existing gas ranges with electric ranges in each unit. I did a load calculation on the feeders to each apartment (60 amp exists). Also on main service - 200 amp exists. I used 08 code Article 220.83 to compute. I don't know exactly what the load is on the house panel, but only lights in the basement and a couple of laundry circuits (Gas dryer), and a central boiler.

My first thoughts were NO WAY adding four electric ranges to existing 200 amp service, but after doing the load calcs??

I'm not sure if I calculated properly - any feedback would be appreciated.

Thanks!



Existing 200 amp service with (4) apartment panels fused at 60 amp and (1) house panel fused at 60 amp.

Each apartment: 650 square feet, and (1) kitchen appliance circuit.

Apartment loads: 650 sq.ft. X 3VA = 1950 VA
(1) appliance circuit = 1500 VA
Existing load: 3450 VA / 240 volts = 14.38 amps
Add 12.5 KW range 12500 VA
New feeder load: 15950 VA
220.83 ( 08 code) : 8000 VA @ 100% = 8000 VA
remainder at 40% 15950-8000= 7950 VA @ 40% = 3180 VA
Total: 11180 VA / 240 volts = 46.58 amps OK on 60 amp panel

Main service load (4) apartments @ 3450 VA = 13800 VA / 240 volts = 57.5 amps plus house panel
Add ranges (4) @ 12.5 KW 50000 VA
Total with added ranges: 63800 VA
1st. 8000 VA @ 100% = 8000 VA
remander @ 40% = 63800-8000=55800 X .4 = 22320 VA
Total: 30320 VA / 240 volts = 126.33 amps plus house panel OK on 200 amp service
 
al hildenbrand

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
Lightitup,

So far your calculation is right on track. Diversity of load is a strange thing.

Are there any fixed appliances in the kitchens that have been added over the decades? Dishwasher, disposal, designated microwave location, etc.?

Dennis,

I'm betting this is an existing 4 plex from the '50s or before.
 
L

lightitup

Member
Location
Minnesota
So far your calculation is right on track. Diversity of load is a strange thing.

Are there any fixed appliances in the kitchens that have been added over the decades? Dishwasher, disposal, designated microwave location, etc.?

Dennis,

I'm betting this is an existing 4 plex from the '50s or before.

Al,

No fixed appliance loads other than (2) units have small window air conditioner plugged into one of the lighting circuits.

Old building each panel has only two lighting circuits and one kitchen appliance circuit.
 
M

MJW

Senior Member
I did a service calc for a 4-plex almost identical to this one last year. Here is what I ended up with.

Unit panels (2 SA, dishwasher, disposal, 652 sq ft) = 56.2 amps

House panel (Boiler, washer, dryer, lighting, recep) = 35.5 amps

Service = 160.3 amps

It looks like our calcs match up fairly close.
 
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