Kitchen Small-Appliance and Laundry Circuit Loading in a Dwelling
A 2,400 sq ft single-family dwelling is being wired. The plan shows a 200 A, 120/240 V single-phase service, a 12 kW electric range, a 5.5 kW electric dryer, a 4.5 kW water heater, a 3 ton central air conditioner (nameplate 24 A at 240 V), a 1/2 hp furnace blower, and a 1,500 VA microwave. The kitchen has two 20 A small-appliance branch circuits and a separate 20 A laundry circuit. The electrician must perform the standard calculation to confirm the 200 A service is adequate and verify the small-appliance and laundry circuit requirements.
1. Perform the standard service calculation and confirm the 200 A service.
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General lighting: 2,400 sq ft x 3 VA = 7,200 VA. Small-appliance: 2 circuits x 1,500 VA = 3,000 VA. Laundry: 1,500 VA. Subtotal general = 11,700 VA. Apply Table 220.42 demand: first 3,000 VA at 100% = 3,000; remaining 8,700 at 35% = 3,045; general demand = 6,045 VA.
Appliances: range 12,000 VA per Table 220.55 (Column C for one range) = 8,000 VA; dryer 5,500 VA at 100% (or 5,000 minimum) = 5,500 VA; water heater 4,500 VA at 100% = 4,500 VA. Appliance subtotal = 18,000 VA.
Largest motor: A/C 24 A x 240 V = 5,760 VA at 100%, plus 25% of largest motor (furnace blower 1/2 hp = 1,000 VA per Table 430.248 at 120 V? use nameplate) - add 25% of the A/C: 1,440 VA. HVAC total = 7,200 VA. Microwave 1,500 VA.
Total = 6,045 + 18,000 + 7,200 + 1,500 = 32,745 VA. At 240 V that is 136.4 A. A 200 A service is more than adequate; a 150 A service would also pass, but 200 A is a reasonable design choice.
2. What are the requirements for the two small-appliance and one laundry branch circuits?
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Per 210.11(C)(1), two or more 20 A small-appliance branch circuits are required to serve kitchen, pantry, dining, and similar areas; they must have no other outlets (210.52(B)(1)) and must be 20 A with 12 AWG or larger copper. Receptacles must be GFCI protected per 210.8(A) for dwelling kitchen countertops. The laundry circuit per 210.11(C)(2) must be 20 A, serve only laundry receptacles, and have no other outlets. Both must be supplied from the service panel, not a subpanel that would not be considered part of the service equipment for this purpose in the standard layout. Verify the 1,500 VA per circuit is used in the calculation and that the circuits are not combined with lighting.
3. The homeowner wants to add a 40 A EV charger in the garage. Does the 200 A service still work?
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A 40 A EV charger is a continuous load, so the branch circuit must be 125% of 40 A = 50 A, requiring a 50 A circuit. Add 40 A x 240 V = 9,600 VA to the service calculation (or 9,600 VA at 100% as a continuous load). New total = 32,745 + 9,600 = 42,345 VA, or 176.4 A. The 200 A service still has capacity. However, check 625.42 and 625.41 for the EVSE rating and whether a load management system is used; if the charger is a 48 A unit, the circuit is 60 A and the load is 11,520 VA, bringing total to 184.4 A, still within 200 A. Verify the panel bus and main breaker ratings and that the garage receptacle is GFCI protected per 210.8(A)(2).