Article 215 Feeders




Minimum Rating and Size

The feeder conductors have to be sized to carry the load as calculated in Article 220, Parts I, II, and III. The minimum size permitted before any adjustments is the total noncontinuous load and 125% of the continuous load. There is one exception where the assembly is rated for operation at 100% of its rating. The feeder circuit grounded conductor cannot be smaller than the requirements of 250.122. If the conductors are run in parallel then 250.122(F) does not apply. If a feeder carries the total load of the service conductors and the ampacity of the service conductor is 55 A or less, the feeder must be sized at least the same. Feeders in mobile homes or individual dwelling units only have to be sized as large as the service entrance conductors. Reference is made to Section 310.15(B)(6) for sizing. There are also fine print notes which state that if the feeder conductors are sized to give a maximum voltage drop of 3% and the total voltage drop of feeders and branch circuits is not larger than 5%, operation should be reasonably efficient. There are requirements for feeders over 600 volts.


Overcurrent Protection

Refer to Article 240, Part I.


Feeders with a Common Neutral


Diagram of Feeders


Feeder Conductor Grounding Means

If equipment grounding conductors are required, refer to Section 250.134.


Ungrounded Conductors Tapped from Grounded Systems

Permitted with a switching device with a pole in each ungrounded conductor.


Ground-Fault Circuit-Interrupter Protection for Personnel

When a feeder supplies 15- and 20-A receptacle branch circuits, a ground-fault circuit interrupter may be installed in the feeder instead of the requirements of 210.8 and 590.6(A).


Ground-Fault Protection of Equipment

Ground-fault protection of equipment in accordance with Section 230.95 must be provided for a feeder in a solidly grounded wye system of 150 to 600 V to ground and a disconnect rated 1000 A or more. There are three exceptions, for a continuous industrial process where an orderly shutdown is required to prevent hazards, fire pumps, and if there is ground-fault protection equipment on the supply side of the feeder. For healthcare occupancies refer to 517.17.


Circuits Derived from Autotransformers


Identification for Feeders

The grounded conductor has to be identified as required by 200.6, and the equipment grounding conductor as required by 250.119. If feeders from more than one voltage system are supplied to premises, then each ungrounded conductor where they are accessible must be identified as to which system they are on. This identification can be by color coding, marking tape, or other approved methods. This marking must be at each feeder panelboard or other distribution equipment.

Article 90 Introduction


Wiring and Protection

Wiring Methods and Materials

Equipment for General Use

Special Occupancies

Special Equipment

Special Conditions


Annex C. Conduit and Tubing Fill Tables for Conductors and Fixture Wires of the Same Size

Annex D. Examples

Annex E. Types of Construction

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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 © 2008-2017.
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