HomeMy WebLinkAboutBLDE-25-134 load calculation Elliott, Ken
From: JACK GRIFFIN ELECTRIC <jackgriffinelectric@comcast.net>
Sent: Wednesday,Janua 2 025 12:22 PM
To: Elliott, Ken
Subject: Fwd: load calc f r 23 Elmcroft �� 2�j -
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On Jan 28, 2025, at 5:43 PM,jackgriffinelectric@comcast.net wrote:
Hi Ken
Here is the load calculation you requested.
Thank
Jack
978-479-2521
Question:
3000 square foot house
• 1 A/C unit, minimum circuit amp: 18
• 1 A/C unit, minimum circuit amp: 13.8
• 1 A/C unit, minimum circuit amp: 8.7
• 1 Electric dryer
• 1 Washer
• 1Oven
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• 1 Dishwasher
• 3 Air handlers, 5 amps each, 240 volts
• 1 Gas boiler
• 1 Car charger, 40 amps, 240 volts
Use the 2023 NEC Alternate Method to determine the required service size.
Step-by-Step Calculation:
1. General Lighting and Receptacle Load:
• 3000 sq. ft. x 3 VA per sq. ft. (as per NEC 220.12):
3000 x 3=9000 VA
2. Small Appliance Circuits:
• Two required small appliance circuits (NEC 220.52(A)), each at 1500 VA:
2 x 1500=3000 VA
3. Laundry Circuit:
• One laundry circuit at 1500 VA (NEC 220.52(B)):
1500 VA
Subtotal = 9000 + 3000 + 1500 = 13,500 VA
4. Apply Demand Factor(First 10 kVA @ 100%, remainder @ 40%):
• First 10,000 VA: 10,000 VA @ 100% = 10,000 VA
• Remaining: 13,500 - 10,000 = 3,500 VA @ 40% = 1,400 VA
Total General Load = 10,000+ 1,400 = 11,400 VA
5. Fixed Appliances:
• Dishwasher: 1200 VA(assumed typical load)
• Electric Dryer: 5000 VA (minimum per NEC 220.54)
• Oven: 8000 VA (assumed standard load)
• Washer: 1200 VA (assumed typical load)
• Air Handlers: 3 units x 240V x 5A= 3600 VA
Subtotal Fixed Appliances = 12,200 + 3600 = 15,800 VA
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6. Demand Factor for Appliances:
Apply 75%demand factor for 4 or more appliances (NEC 220.53):
15,800 VA x 75% = 11,850 VA
7. HVAC Loads:
• Largest A/C Unit Only (per NEC 220.82(C)):
18A x 240V=4320 VA
The two smaller units (13.8A and 8.7A) are not included, and the gas boiler is ignored since it's not
electric.
HVAC Total =4320 VA
8. Car Charger:
• 40A x 240V =9600 VA
Final Load Calculation:
1. General Load: 11,400 VA
2. Fixed Appliances: 11,850 VA
3. HVAC Load: 4320 VA
4. Car Charger: 9600 VA
Total Load = 11,400 + 11,850+4320 + 9600 =37,170 VA
Convert to Amps:
• 37,170VA_ 240V= 154.88A
Service Size:
Round up to the next standard breaker size: 200A service required.
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