Help with load calculations... sanity check

[CubGirl]

Hi everybody!

Can someone kindly look over these load calculations? This is my first time doing this and I'd like feedback.
Thanks!

Unit #1
220.12 General Lighting

3va/ft^2 of floor area, including unused space adaptable for future use
Floor Area= 1582 ft^2 = 4,746 va​

220.52(A) Small Appliance Load

1500 va for each 20 amp branch circuit required per 210.1(C)(1) in EACH kitchen, pantry, breakfast
room, dining room, or similar areas
# of Small Appliance Branch Circuits = 3 X 1500 va = 4,500 va​

220.52(B) Laundry Load

# of Laundry Branch Circuits = 1 X 1500 va = 1,500 va​

Total General Lighting & Appliance Load = 10,746 va

220.42 Lighting Load Feeder Demand Factors

First 3000 or less at 100% = 3,000 va
From 3001 to 120,000 at 35% = 2,711 va
Remainder over 120,000 at 25% = 0 va​

Total Lighting Demand Load = 5,711 va

220.54 Electric Clothes Dryers

Dryer #1, Greater of Nameplate KW rating or 5kw = 7.20 kw = 7,200.00 w​

220.55 Electric Ranges--Dwelling Units

Electric Range Nameplate KW = 10.00 kw = 10,000 w​

220.51 Largest of Fixed electric space heating loads or A/C load:
220.21 Non-coincident Loads

Fixed Electric Space Heat #1 - w A/C#1 = 43.0 MCA@208-240V​

Total Non-coincident Load = 7,632 va

220.53 Appliance load--Dwelling Units

Qty Description va (watts)
1 Dishwasher(s) = 1200
1 Microwave(s) = 1100
1 Refrigerator(s) = 350
1 Rinnai Gas H2O Heater = 76
1 Stand Alone Ice Maker = 550​

Total Connected Appliance Load = 3,276.00 va
220.53 Appliance load--Dwelling Units (75% Total Appliance Demand Load) = 2,457.00 va

220.50 Motor Loads @ 120 Volts

Qty Description Amps
1 Garbage Disposal(s) = 8.1​

Total Motor Load = 972 va

430.24 25% of Largest Motor Load = 243 va​

Total Motor Demand Load = 1,215 va

TOTAL CALCULATED DEMAND LOAD in Volt-amperes = 34,215 va
TOTAL CALCULATED DEMAND LOAD in AMPS @ 1 Phase 3 Wire, 120/ 240 Volts = 143 Amps
MINIMUM SERVICE REQUIRED = 143 AMPS
SERVICE SIZE REQUEST = 150 Amps for Unit #1

Unit #2
220.12 General Lighting

3va/ft^2 of floor area, including unused space adaptable for future use
Floor Area= 500 ft^2 = 1,500 va​

220.52(A) Small Appliance Load

1500 va for each 20 amp branch circuit required per 210.1(C)(1) in EACH kitchen, pantry, breakfast
room, dining room, or similar areas
# of Small Appliance Branch Circuits = 2 X 1500 va = 3,000 va​

220.52(B) Laundry Load

# of Laundry Branch Circuits = 1 X 1500va = 1,500 va​

Total General Lighting & Appliance Load = 6,000 va

220.42 Lighting Load Feeder Demand Factors

First 3000 or less at 100% 3,000 va
From 3001 to 120,000 at 35% = 1,050 va
Remainder over 120,000 at 25% = 0 va​

Total Lighting Demand Load = 4,050 va

220.54 Electric Clothes Dryer

Dryer #1, Greater of Nameplate KW rating or 5kw= 7.20 kw = 7,200 w​

220.55 Electric Ranges--Dwelling Units

Electric Cooktop Nameplate KW= 2.00 kw = 2,000 w​

220.51 Largest of Fixed electric space heating loads or A/C load:
220.21 Non-coincident Loads

Fixed Electric Space Heat #1 - w A/C#1 = 13.4 MCA@208-240V​

Total Non-coincident Load = 3,216 va

220.53 Appliance load--Dwelling Units

Qty Description va(watts) Qty Description va (watts)
1 Dishwasher(s) = 1100 w
1 Freezer(s) = 300 w
1 Microwave(s) = 1000 w
1 Refrigerator(s) = 350
1 ECO 11 Water Heater(s) = 13680 w (240v * 57a)
Total Connected Appliance Load = 16,430 va​

220.53 Appliance load--Dwelling Units (75% Total Appliance Demand Load) = 12,323 va

220.50 Motor Loads @ 120 Volts

Qty Description Amps Qty Description Amps
1 Garbage Disposal(s) 6.3
Total Motor Load = 756 va​

430.24 25% of Largest Motor Load = 189 va
Total Motor Demand Load = 945 va

TOTAL CALCULATED DEMAND LOAD in Volt-amperes = 29,734 va
TOTAL CALCULATED DEMAND LOAD in AMPS @ 1 Phase 3 Wire, 120/ 240 Volts = 124 Amps
MINIMUM SERVICE REQUIRED = 125 AMPS
SERVICE SIZE REQUEST = 125 Amps for Unit #2

These calculations are for two units in a building that has 200 amp service for the entire building. I asked for the electricity to be split between the two units. Initially, I requested two 125 amp panels to be installed in each unit (but instead got two 100 amp panels). However from these load calculations, I believe Unit #1 needs a 150 amp breaker panel, not 125 amp and Unit # 2 is ok with the 125 amps.

Should the electrician have done these 2 load calculations in order to determine the correct panel size for each unit? Am I correct that these calculations can be used to determine the units' panel size? Am I also correct that Units 1 & 2 require 150 amp & 125 amp panels, respectively?

Electricity's kinda fun...

Thanks for your help.
Cub

 

[hj]

I doubt that ANYONE does a load calculation for a residence, and when it IS done, for commercial buildings, the mechanical engineer does it, NOT the electrician.

 

[Sponsor]

 

[CubGirl]

I doubt that ANYONE does a load calculation for a residence, and when it IS done, for commercial buildings, the mechanical engineer does it, NOT the electrician.

really? wow, here's what i know:
after the job was done & inspection complete, two days went by & the utility company didn't energize. I was told by electrician they'd turn it on when they saw the card in the meter hole. after complaining, the electrician told me to call engineering dept at utility company. i did & he said he could not authorize it to be turned on because he had no info on the work. i asked him what he needed. he said electrician was supposed to submit a load calculation. i told him they took 200 amps meter out, installed a 2 unit gang meter & split the amps between the two units, each getting 125 amps (because that's what i thought at the time).

i then called the electrician & gave him the engineer's contact info & told him what he wanted. six hours later the power was back on. i don't know if they supplied a load calculation or not.

this building is zoned both commercial and residential. when i renovated it in 2009, i had to meet commercial specs. maybe because it's commercial is why utility company wanted load calculations?

anyway, whether it's necessary or not, could the load calculations be used to determine panel sizes? otherwise, it's a hit & miss.

sorry if these questions are too technical for this forum...

thanks
cub

 

[hj]

As practical matter, residential panels are almost ALWAYS oversized. The only reason for a load calc would be if they wanted to use the smallest, i.e,. cheapest, one possible.