All conditions and calculations the same as for Optional Calculations for Multifamily Dwelling of Example No. D4(b) served at 120/40 volt, single phase except service to each dwelling unit shall be two-phase legs and neutral.
Minimum Number of Branch Circuits Required for Each Dwelling Unit (See 210.11)
Range circuit (see Table 220.55, Column B): 8000 volt-amperes x 80% ÷ 208 volt = 30.7 amperes or a circuit of two 8 AWG conductors and one 10 AWG conductor per 220.19(A)(3).
Space heating: 6000 volt-amperes ÷ 208 volts = 28.8 amperes. Two 20-ampere, 2-pole circuits required, 12 AWG conductors.
Minimum Size Feeder Required for Each Dwelling Unit
|
|
Net calculated load: 18,782 volt-amperes ÷ 208 volts |
= 90.3 amperes |
Net calculated lighting load (line to neutral): 3882 volt-amperes ÷ 2 legs ÷ 120 volts/leg |
= 16.2 amperes |
Line to line = 14,900 volt-amperes ÷ 208 volts |
71.6 amperes |
|
87.8 amperes |
Minimum Size Feeder Required for Service Equipment to Meter Bank (20 Dwelling Units)
Net Calculated Load
Feeder Neutral Load
Minimum Size Main Feeder Required (Less House Load) (40 Dwelling Units)
Net Calculated Load
Main Feeder Neutral Load
Further Demand Factor [See 220.61(B)] |
|
|
200.0 A |
|
69.2 A |
|
269.2 A |
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