Where to Find Overcurrent Protection in the Code

ARTICLE 240 Overcurrent Protection

Since overcurrent protection is a central concern of the NEC®, Article 240 is one of the most important in the Code. The FPN to this section directs the reader to 110.9 for requirements for interrupting ratings and 110.10 for requirements for protection against fault currents.  

I. General (240.1 through 240.15)

This part begins with a long list of cross references to other places in the Code where overcurrent protection requirements for specific types of equipment or in specific instances can be found (see the table below).

II. Location (240.21 through 240.24)

This section gives detailed requirements for service, feeder, and branch circuit overcurrent protection devices and where they can be located. For instance, it states that in dwelling units, overcurrent devices are not permitted to be located in bathrooms.

III. Enclosures (240.30 through 240.33)

This part introduces the enclosure as a means of protecting overcurrent devices from physical damage and requires that such enclosures be mounted in a vertical position.

IV. Disconnecting and Guarding (240.40 and 240.41)

This part deals with disconnecting means for fuses and circuit breakers, and with protecting people from injury due to arcing or suddenly moving parts of these overcurrent devices.

V. Plug Fuses, Fuseholders, and Adapters (240.50 through 240.54)

This part contains rules for classifying plug fuses and for ensuring that different types of plug fuses are noninterchangeable.

VI. Cartridge Fuses and Fuseholders (240.60 and 240.61)

This part provides rules for classifying cartridge fuses and for ensuring that different types of cartridge fuses are noninterchangeable.

VII. Circuit Breakers (240.80 through 240.86)

This part contains requirements for the marking, rating, and application of circuit breakers. For instance, circuit breakers used as switches for fluorescent lighting must be listed and marked either SWD or HID, but only HID breakers can me used for high-intensity discharge lighting.

VIII. Supervised Industrial Installations (240.90 and 240.92)

This part provides the rules for overcurrent protection, overload protection, and physical protection of conductors in industrial plants that have their own maintenance and supervisory personnel. The requirements for protection in these plants are less stringent than in unsupervised locations.

IX. Overcurrent Protections for over 600 Volts, Nominal (240.100 and 240.101)

As occurs elsewhere in the Code, this part provides special rules for systems operating at higher voltages.

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 Other Articles

Equipment	Article
Air-conditioning and refrigerating equipment	440
Appliances	422
Assembly occupancies	518
Audio signal processing, amplification, and reproduction equipment	640
Branch circuits	210
Busways	368
Capacitors	460
Class 1, Class 2, and Class 3 remote-control, signaling, and power-limited circuits	725
Cranes and hoists	610
Electric signs and outline lighting	600
Electric welders	630
Electrolytic cells	668
Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chairlifts	620
Emergency systems	700
Fire alarm systems	760
Fire pumps	695
Fixed electric heating equipment for pipelines and vessels	427
Fixed electric space-heating equipment	424
Fixed outdoor electric deicing and snow-melting equipment	426
Generators	445
Health care facilities	517
Induction and dielectric heating equipment	665
Industrial machinery	670
Luminaires, lampholders, and lamps	410
Motion picture and television studios and similar locations	530
Motors, motor circuits, and controllers	430
Phase converters	455
Pipe organs	650
Receptacles	406
Services	230
Solar photovoltaic systems	690
Switchboards and panelboards	408
Theaters, audience areas of motion picture and television studios, and similar locations	520
Transformers and transformer vaults	450
X-ray equipment	660

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