2. Chapter 12
Branch Circuits and Feeders

3. Objectives
Identify the feeder and branch circuit portions of a distribution system.
Describe the various types of branch circuits.
Define the functions of a feeder and the functions of branch-circuit conductors.
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4. Objectives
Calculate lighting and receptacle loads using Code requirements.
Size branch circuits in accordance with the Code.
Determine branch circuit overcurrent protection required by the Code.
Use the Code to size feeder conductors.
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5. Definitions Service conductors Feeder Subfeeders
From power company terminals to main service disconnect
Feeder
From main distribution or disconnect to another distribution/load center or panelboard
Subfeeders
To panelboards, load centers, and disconnect switches that supply branch circuits

6. Definitions Panelboard Branch circuits
Single or multiple panels containing switches, fuses, and circuit breakers
Branch circuits
Transfer power to load devices

7. Definitions
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8. Branch Circuits Extend past final overcurrent protective device
Classifications
Individual, multioutlet, general purpose, appliance, multiwire
Sized for load it will supply
Depends on rating of overcurrent device

9. Branch Circuits
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10. Branch-Circuit Voltage
Limitations based on equipment being supplied
Residences and hotel rooms circuits
Circuits 120 volts and less
Branch circuits between 120 and 277 volts
Circuits between 277 and 600 volts

11. Branch Circuits Amperage rating greater than maximum load
Ampacity in multiple-load circuits corresponds to rating of overcurrent protective device
Multiwire branch circuits
Grounded conductor and two or more ungrounded conductors
Individual or multioutlet circuit

12. Conductor Color Code Grounded conductor 6 AWG or less
White or with color stripe, gray, or white stripes
Wires from different systems in same raceway
Neutrals distinguished by different color
Equipment grounding conductor
Green or with yellow stripes, or bare
Hot conductors are black, blue, or red

13. Continuous Loads Longer than three hours
Must not exceed 80% of circuit rating allotted
80% rule not used with overcurrent protective device for continuous operation at 100%

14. Lighting Loads General lighting load Show-window lighting load
Determined by load per area method or full-load current of fixtures used
Show-window lighting load
Not part of general lighting load
200 volt-amperes per linear foot or max volt-ampere rating of equipment

15. General Lighting Loads
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16. Code Alert Shadow Window Article 100
Any window displaying goods or advertising
Light in Show Windows
Section
Chain-supported fixtures may be externally wired
No other externally wired fixtures

17. Lighting Loads Track lighting Sign and outline lighting
Minimum load is 150 volt-amperes for 2′ of track
Sign and outline lighting
At least one circuit dedicated
Minimum load of 1200 volt-amperes
Additional loads computed separately

18. Code Alert Lighting Track Section 410.2
Manufactured assembly designed to support and energize luminaries that can be repositioned on track. Can alter length by addition or subtraction of track sections.

19. Demand Factors
Lighting load may be derated for feeder, panel, or service computations
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20. Receptacle Loads Most do not supply continuous loads
Receptacle ampere rating based on circuit type
Individual or multiple
Number of receptacles on branch circuit
Multiply circuit voltage and amperage
Divide by 180 volt-amperes

21. Equipment Loads Most are noncontinuous
Required load supplied identical to equipment requirement
Hard-wired or cord-and-plug connected
Ampacity of conductors equal to or exceed that of appliance
125% of motor current rating

22. Code Alert Kitchen Demand Factors Section 220.56
Demand factors applied to thermostatic control or intermittent use as kitchen equipment.
Not applied to space-heating, ventilating, or air-conditioning equipment

23. Heating and Cooling Loads
Heating load computed at 100% of nameplate rating
Disconnect and overcurrent protection required
General rules for sizing overcurrent protection devices

24. Heating and Cooling Loads
Air-conditioning load determined from nameplate data
Larger branch-circuit current rating or full-load current rating for sizing
125% of the largest motor for two or more motors
115% of the full-load current for single motor

25. Feeders
Conductors between service equipment and branch-circuit overcurrent devices
Loading dependent on total power requirement of system
Factors for correct feeder size, type, and overcurrent protection

26. Commercial Service Load Computation Procedure
Determine general lighting load
If continuous load, increase load by 125%
Feeder and service loads, apply lighting demand factor
Compute air-conditioning and heating loads
Compute receptacle outlets
Demand factors for receptacle and kitchen equipment loads

27. Summary of Commercial Service Load Computation Procedure
Add sign lighting load
Compute motor loads
Increase largest motor load by 25%
Size service and service conductors
Size grounded service conductor
Derate neutral load by 70%, if over 200 amperes