Dwelling has a floor area of 2000 sq. ft. exclusive of an unfinished cellar not adaptable for future use, unfinished attic, and open porches. It has a 12-kW range, 4.5-kW water heater, a 1.2-kW dishwasher, a 5-kW clothes dryer, a 2 ½-ton (24-ampere) heat pump with 15-kW of back-up heat.
Heat Pump kVA Calculation
This 5.76 kVA is less than 15 kVA of the backup heat; therefore, the heat pump load need not be included in the service calculation. [See 220.82(C).]
General Load |
|
---|---|
2000 sq. ft. at 3 volt-amperes |
6000 VA |
Two 20-ampere appliance outlet circuits at 1500 volt-amperes each |
3000 VA |
Laundry circuit |
1500 VA |
Range (at nameplate rating) |
12,000 VA |
Water heater |
4500 VA |
Dishwasher |
1200 VA |
Clothes dryer |
5000 VA |
Subtotal general load |
33,200 VA |
First 10 kVA of general load at 100% |
= 10,000 VA |
Remainder of general load at 40% (23,200 VA x 0.4) |
= 9280 VA |
Total net general load |
= 19,280 VA |
Heat Pump and Supplementary Heat[*] |
---|
|
15-kW electric heat: |
5760 VA + (15,000 VA x 65%) = 5.76 kVA + 9.75 kVA = 15.51 kVA |
[*] If supplementary heat is not on at the same time as heat pump, heat pump kVA need not be added to total.
Totals: |
|
|
19,280 VA |
|
15,510 VA |
|
34,790 VA |
Calculated Load for Service
Therefore, this dwelling unit may be served by a 150-ampere service.
Article 90 Introduction
General
Wiring and Protection
Wiring Methods and Materials
Equipment for General Use
Special Occupancies
Special Equipment
Special Conditions
Tables
Annex C. Conduit and Tubing Fill Tables for Conductors and Fixture Wires of the Same Size
Annex D. Examples
Annex E. Types of Construction