Example No. D1(a) One-Family Dwelling

The dwelling has a floor area of 1500 square feet exclusive of an unfinished cellar not adaptable for future use, unfinished attic, and open porches. Appliances are a 12-kW range and a 5.5-kW, 240-volt dryer. Assume range and dryer kW ratings equivalent to kVA ratings in accordance with Sections 220.54 and 220.55.

Calculated Load [See 220.40]

General lighting load: 1500 sq. ft. at 3 volt-amperes per sq. ft. = 4500 volt-amperes.

Minimum Number of Branch Circuits Required [See Sec-tion 210.11(A)]

General lighting load: 4500 volt-amperes ÷ 120 V = 37.5 A. This requires three 15-A, 2-wire or two 20-A, 2-wire circuits.

Small appliance load: two 2-wire, 20-A circuits [see 210.11(C)(1)].

Laundry load: one 2-wire 20-A circuit [see 210.11(C)(2)].

Bathroom branch circuit: One 2-wire, 20-A circuit (no additional calculation is required for this circuit) [see 210.11(C)(3)].

Minimum Size Feeder Required [See 220.40]

General lighting

4500 VA

Small appliance

3000 VA


1500 VA

Total general light and small appliance

9000 VA

3000 volt-amperes at 100%

3000 VA

9000 VA - 3000 VA = 6000 volt-amperes at 35%

2100 VA

Net load

5100 VA

Range (see Table 220.55)

8000 VA

Dryer load (see Table 220.54)

5500 VA

Net calculated load

18,600 VA

Net calculated load for 120/240-volt 3-wire single-phase service or feeder

Sections 230.42(B) and 230.79 require service conductors and disconnecting means rated not less than 100 amperes.

Calculation for Neutral for Feeder and Service

Lighting and small appliance load

5100 VA

Range: 8000 volt-amperes at 70% (see 220.61)

5600 VA

Dryer: 5500 volt-amperes at 70% (see 220.61)

3850 VA


14,550 VA

Calculated Load for Neutral

Pocket Guide to the National Electrical Code 2005
Pocket Guide to the National Electrical Code(R), 2005 Edition (8th Edition)
ISBN: 0131480014
EAN: 2147483647
Year: 2004
Pages: 120
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