Example No. D2(a) Optional Calculation for One-Family Dwelling Heating Larger than Air Conditioning [See Section 220.82]
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. It has a 12-kW range, a 2.5-kW water heater, a 1.2-kW dishwasher, 9 kW of electric space heating installed in five rooms, a 5-kW clothes dryer, and a 6-ampere, 230-volt room air-conditioning unit. Assume range, water heater, dishwasher, space heating, and clothes dryer kW ratings equivalent to kVA.
Air conditioner kVA calculation is 6A x 230V ÷ 1000 = 1.38 kVA
This 1.38 kVA [Item 1 from 220.82(C)] is less than 40% of 9 kVA of separately controlled electric heat [Item 6 from 220.82(C)], so the 1.38 kVA need not be included in the service calculation.
|
General Load |
|
|---|---|
|
1500 sq. ft. at 3 volt-amperes |
4500 VA |
|
Two 20-amp. appliance outlet circuits at 1500 volt-amperes each |
3000 VA |
|
Laundry circuit |
1500 VA |
|
Range (at nameplate rating) |
12,000 VA |
|
Water heater |
2500 VA |
|
Dishwasher |
1200 VA |
|
Clothes dryer |
5000 VA |
|
Total |
29,700 VA |
Application of Demand Factor [See 220.82(B)]
|
First 10 kVA of general load at 100% |
= 10,000 VA |
|
Remainder of general load at 40% (19.7 kVA x .4) |
= 7880 VA |
|
Total of general load |
= 17,880 VA |
|
9 kVA of heat at 40% (9000 VA x .4) |
= 3600 VA |
|
Total |
= 21,480 VA |
Calculated load for service size
Therefore, the minimum service size would be 100 amperes in accordance with 230.42 and 230.79.
|
Feeder Neutral Load (per 220.61) |
|
|---|---|
|
1500 sq. ft. at 3 volt-amperes |
4500 VA |
|
Three 20-amp. circuits at 1500 volt-amperes |
4500 VA |
|
9000 VA |
|
3000 volt-amperes at 100% |
3000 VA |
|
9000 VA - 3000 VA = 6000 volt-amperes at 35% |
2100 VA |
|
5100 VA |
|
Range8 kVA at 70% |
5600 VA |
|
Clothes dryer5 kVA at 70% |
3500 VA |
|
Dishwasher |
1200 VA |
|
15,400 VA |
Calculated Load for Neutral
Article 90 Introduction
General
Wiring and Protection
- Article 200 Use and Identification of Grounded Conductors
- Article 210 Branch Circuits
- Article 215 Feeders
- Article 220 Branch-Circuit, Feeder, and Service Calculations
- Article 225 Outside Branch Circuits and Feeders
- Article 230 Services
- Article 240 Overcurrent Protection
- Article 250 Grounding and Bonding
- Article 280 Surge Arresters
- Article 285 Transient Voltage Surge Suppressors (TVSSs)
Wiring Methods and Materials
- Article 300: Wiring Methods
- Article 310 Conductors for General Wiring
- Article 312 Cabinets, Cutout Boxes, and Meter Socket Enclosures
- Article 314 Outlet, Device, Pull, and Junction Boxes; Conduit Bodies; Fittings; and Handhole Enclosures
- Article 320 Armored Cable Type AC
- Article 322 Flat Cable Assemblies Type FC
- Article 324 Flat Conductor Cable Type FCC
- Article 326 Integrated Gas Spacer Cable Type IGS
- Article 328 Medium-Voltage Cable Type MV
- Article 330 Metal-Clad Cable Type MC
- Article 332 Mineral-Insulated, Metal-Sheathed Cable Type MI
- Article 334 Nonmetallic-Sheathed Cable Types NM, NMC, and NMS
- Article 336 Power and Control Tray Cable Type TC
- Article 338 Service-Entrance Cable Types SE and USE
- Article 340 Underground Feeder and Branch-Circuit Cable Type UF
- Article 342 Intermediate Metal Conduit Type IMC
- Article 344 Rigid Metal Conduit Type RMC
- Article 348 Flexible Metal Conduit Type FMC
- Article 350 Liquidtight Flexible Metal Conduit Type LFMC
- Article 352 Rigid Nonmetallic Conduit Type RNC
- Article 353 High Density Polyethylene Conduit Type HDPE Conduit
- Article 354 Nonmetallic Underground Conduit with Conductors Type NUCC
- Article 356 Liquidtight Flexible Nonmetallic Conduit Type LFNC
- Article 358 Electrical Metallic Tubing Type EMT
- Article 360 Flexible Metallic Tubing Type FMT
- Article 362 Electrical Nonmetallic Tubing Type ENT
- Article 366 Auxiliary Gutters
- Article 374 Cellular Metal Floor Raceways
- Article 382 Nonmetallic Extensions
- Article 384 Strut-Type Channel Raceway
- Article 386 Surface Metal Raceways
- Article 388 Surface Nonmetallic Raceways
- Article 390 Underfloor Raceways
- Article 392 Cable Trays
- Article 394 Concealed Knob-and-Tube Wiring
- Article 396 Messenger Supported Wiring
- Article 398 Open Wiring on Insulators
Equipment for General Use
- Article 400: Flexible Cords and Cables
- Article 402: Fixture Wires
- Article 404: Switches
- Article 406: Receptacles, Cord Connectors, and Attachment Plugs (Caps)
- Article 408: Switchboards and Panelboards
- Article 409: Industrial Control Panels
- Article 410: Luminaires (Lighting Fixtures), Lampholders, and Lamps
- Article 411: Lighting Systems Operating at 30 Volts or Less
- Article 422: Appliances
- Article 424: Fixed Electric Space Heating Equipment
- Article 426: Fixed Outdoor Electric De-Icing and Snow-Melting Equipment
- Article 427: Fixed Electric Heating Equipment for Pipelines and Vessels
- Article 430: Motors, Motor Circuits, and Controllers
- Article 440: Air Conditioning and Refrigerating Equipment
Special Occupancies
- Article 500 Hazardous (Classified) Locations, Classes I, II, and III, Divisions 1 and 2
- Article 501 Class I Locations
- Article 502 Class II Locations
- Article 503 Class III Locations
- Article 504 Intrinsically Safe Systems
Special Equipment
Special Conditions
- Article 700 Emergency Systems
- Article 701 Legally Required Standby Systems
- Article 702 Optional Standby Systems
Tables
- Tables
- Notes to Tables
- Tables 11(A) and 11(B)
- Notes for Tables 11(A) and 11(B)
- Tables 12(A) and 12(B)
- Notes for Tables 12(A) and 12(B)
Annex C. Conduit and Tubing Fill Tables for Conductors and Fixture Wires of the Same Size
Annex D. Examples
- Annex D. Examples
- Example No. D1(a) One-Family Dwelling
- Example No. D1(b) One-Family Dwelling
- Example No. D2(a) Optional Calculation for One-Family Dwelling Heating Larger than Air Conditioning [See Section 220.82]
- Example No. D2(b) Optional Calculation for One-Family Dwelling, Air Conditioning Larger than Heating [See 220.82(A) and 220.82(C)]
- Example No. D2(c) Optional Calculation for One-Family Dwelling with Heat Pump(Single-Phase, 240/120-Volt Service) (See 220.82)
- Example No. D3 Store Building
- Example D3(a) Industrial Feeders in a Common Raceway
- Example No. D4(a) Multifamily Dwelling
- Example No. D4(b) Optional Calculation for Multifamily Dwelling
- Example No. D5(a) Multifamily Dwelling Served at 208Y/120 Volts, Three Phase
- Example No. D5(b) Optional Calculation for Multifamily Dwelling Served at 208Y/120 Volts, Three Phase
- Example No. D6 Maximum Demand for Range Loads
- Example No. D8 Motor Circuit Conductors, Overload Protection, and Short-Circuit and Ground-Fault Protection
- Example No. D9 Feeder Ampacity Determination for Generator Field Control
- Example No. D10 Feeder Ampacity Determination for Adjustable-Speed Drive Control [See 215.2, 430.24, 620.13, 620.14, 620.61, Tables 430.22(E), and 620.14]
- Example No. D11 Mobile Home (See 550.18)
- Example No. D12 Park Trailer (See 552.47)
Annex E. Types of Construction
EAN: 2147483647
Pages: 120
