|
|
|
|
ARTICLE 440 Air-Conditioning and Refrigerating Equipment
Article 440 amends and supplements the provisions of Article 430, to provide special requirements for air-conditioning and refrigerating equipment that uses hermetic refrigerant motor-compressors, and for the branch circuits and controllers for that equipment.
I. General (440.1 through 440.8)
Part I provides definitions unique in application the type of equipment covered in Article 440 and also contains requirements covering equipment ratings, markings, and selection of branch-circuit conductors for electric motor-driven air-conditioning and refrigerating equipment. Section 440.3 states that Articles 422, 424, or 430 apply to air-conditioning equipment that does not use hermetic refrigerant motor-compressors.
II. Disconnecting Means (440.11 through 440.14)
Part II provides requirements for selecting the disconnecting means for hermetic refrigerant motor-compressors. Section 440.12(A) specifies that Tables 430.148 through 430.151(B) to determine equivalent horsepower ratings for the purpose of selecting disconnecting means.
III. Branch-Circuit Short-Circuit and Ground-Fault Protection (440.21 and 440.22)
Part III specifies the means of protecting motor branch-circuit conductors, motor controllers, and motors from the effects of short circuits and ground faults. Because of the inrush current associated with this type of equipment, the requirements in this part amend the general branch-circuit overcurrent protection rules of Article 240. Motor-compressor branch-circuit short-circuit and ground-fault protective devices are permitted by Section 440.22(A) to have a rating or setting from 175 percent up to 225% of the motor-compressor’s rated-load current or branch-circuit selection current, whichever is greater.
IV. Branch-Circuit Conductors (440.31 through 440.35)
Part IV contains, rules for sizing the branch circuit conductors supplying single-motor compressor loads, multi- compressor loads, multimotor loads, and combination loads consisting of a hermetic refrigerant motor-compressor in addition to a lighting or appliance load.
V. Controllers for Motor Compressors (440.41)
The provisions of Part V require that motor-compressor controllers have both a continuous-duty full-load current rating and locked-rotor current rating. Tables 430.148 through 430.151(B) can be used to determine the required minimum full-load and locked-rotor current ratings for horsepower-rated motors.
VI. Motor-Compressor and Branch-Circuit Overload Protection (440.51 through 440.55)
Part VI provides requirements for protection of motor-compressors, controllers, and branch-circuit conductors against overheating due to motor overload and failure to start. Protective devices mentioned include overload relays, thermal protectors, fuses, inverse-time circuit breakers, and solid-state protective systems designed specifically for a particular motor-compressor. The devices included here are typically not providing the same protection as branch-circuit overcurrent devices. Motor-compressor overload protectors are not a substitute for the branch-circuit overcurrent protection required by Article 240 and by Part III of Article 440.
VII. Provisions for Room Air Conditioners (440.60 through 440.65)
The requirements in Part VII apply to window, in-wall, and console air-conditioning units that are single-phase and operate at 250 volts or less, and are either hard-wired or cord-and-plug connected. According to 440.62(C), the rating of a cord-and-plug connected room air conditioner must not exceed 80 percent of the rating of an individual branch circuit or 50 percent of the rating of a branch circuit that also supplies other loads or general-use receptacles. | 440 | |
|
Article 210: Branch Circuits
Article 210 covers the requirements for electrical distribution system conductors. It contains basic rules for defining required branch circuits, the locations of lighting and receptacle outlets and switches, and maximum loading and overcurrent protection for branch circuits, including ground-fault circuit interrupters (GFCIs) and arc-fault circuit interrupters (AFCIs).
I. General Provisions (210.1 Through 210.12)
Part I covers all branch circuits in all occupancies, including multiwire branch circuits, ground-fault circuit interrupters (GFCIs), and arc-fault circuit interrupters (AFCIs).
II. Branch-Circuit Ratings (210.19 Through 210.25)
Part I covers ampacity and overcurrent protection of branch-circuit conductors. Content includes ampere ratings of outlet devices, permissible branch circuits of different ampere ratings, continuous and noncontinuous loads, and common area branch circuits.
III. Required Outlets (210.50 Through 210.70)
Part III covers outlets required for dwelling units; guest rooms or guest suites; show windows; and heating, air-conditioning, and refrigeration equipment, as well as lighting outlets required in dwelling and other units.
Specific-Purpose Branch Circuits
|
Equipment |
Article |
Section |
|
Air-conditioning and refrigerating equipment |
|
440.6, 440.31, 440.32 |
|
Audio signal processing, amplification, and reproduction equipment |
|
640.8 |
|
Busways |
|
368.17 |
|
Circuits and equipment operating at less than 50 volts |
720 |
|
|
Central heating equipment other than fixed electric space-heating equipment |
|
422.12 |
|
Class 1, class 2, and class 3 remote-control, signaling, and power-limited circuits |
725 |
|
|
Cranes and hoists |
|
610.42 |
|
Electric signs and outline lighting |
|
600.6 |
|
Electric welders |
630 |
|
|
Electrified truck parking space |
626 |
|
|
Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts |
|
620.61 |
|
Fire alarm systems |
760 |
|
|
Fixed electric heating equipment for pipelines and vessels |
|
427.4 |
|
Fixed electric space-heating equipment |
|
424.3 |
|
Fixed outdoor electrical deicing and snow-melting equipment |
|
426.4 |
|
Information technology equipment |
|
645.5 |
|
Infrared lamp industrial heating equipment |
|
422.48, 424.3 |
|
Induction and dielectric heating equipment |
665 |
|
|
Marinas and boatyards |
|
555.19 |
|
Mobile homes, manufactured homes, and mobile home parks |
550 |
|
|
Motion picture and television studios and similar locations |
530 |
|
|
Motors, motor circuits, and controllers |
430 |
|
|
Pipe organs |
|
650.7 |
|
Recreational vehicles and recreational vehicle parks |
551 |
|
|
Switchboards and panelboards |
|
408.52 |
|
Theaters, audience areas of motion picture and television studios, and similar locations |
|
520.41, 520.52, 520.62 |
|
X-ray equipment |
|
660.2, 517.73 |
|
| | 210 | |
Cable Articles, NEC® Articles 320 Through 340
Articles 320 through 340 cover the use, installation, and construction specifications for various types of cable assemblies. A cable can be considered as an assembly of one or more conductors inside an outer jacket, sheath, or armor that provides physical protection to the conductor(s). Most of the cables included in Chapter 3 of the Code consist of two or more insulated current-carrying circuit conductors plus an equipment grounding conductor. This grounding conductor can be a separate wire, either bare or insulated; in some cases the metal sheath or armor of the cable serves as the equipment grounding conductor.
ARTICLE 320 Armored Cable: Type AC
ARTICLE 322 Flat Cable Assemblies: Type FC
ARTICLE 324 Flat Conductor Cable: Type FCC
ARTICLE 326 Integrated Gas Spacer Cable: Type IGSC
ARTICLE 328 Medium Voltage Cable: Type MV
ARTICLE 330 Metal-Clad Cable: Type MC
ARTICLE 332 Mineral-Insulated, Metal-Sheathed Cable: Type MI
ARTICLE 334 Nonmetallic-Sheathed Cable: Types NM, NMC, and NMS
ARTICLE 336 Power and Control Tray Cable: Type TC
ARTICLE 338 Service-Entrance Cable: Types SE and USE
ARTICLE 340 Underground Feeder and Branch-Circuit Cable: Type UF
Each of these articles is organized in a uniform manner, with parallel numbering schema, making it easier to find similar information for different wiring methods. Each of the articles in Chapter 3 is divided into the following parts:
I. General (Beginning with 3xx.1)
II. Installation (Beginning with 3xx.10)
III. Construction Specifications (Beginning with 3xx.100) | 320, 322, 324, 326, 328, 330, 332, 334, 336, 338, 340 | |
ARTICLE 522 Control Systems for Permanent Amusement Attractions
Article 522 was added to the 2008 NEC to provide requirements for the installation of control power sources and control circuit conductors for integral electrical equipment at the more than 450 amusement theme parks operating in the United States. These permanent facilities have entertainment features fixed in place. The requirements of Article 525 apply only to temporary facilities such as carnivals, circuses, and fairs that consist of portable modules and that are moved from place to place.
I. General (522.1 through 522.7)
Part I provides definitions, maintenance requirements, and general voltage limitations for permanent amusement attractions. The control voltage used is a maximum of 150 volts, nominal, ac to ground or 300 volts dc to ground.
II. Control Circuits (522.10)
Part II contains requirements for maximum voltage of and overcurrent protection of the varying types of power sources that might supply amusement control circuits. Control circuits supplied by transformers also are required by this section to comply with parts of Article 450, Transformers.
III. Control Circuit Wiring Methods (522.20 through 522.28)
Part III contains requirements for sizing, installation, and overcurrent protection of conductors for control circuits at permanent amusements.
ARTICLE 525 Carnivals, Circuses, Fairs, and Similar Events
Article 525 covers the installation of portable wiring and equipment for temporary amusement attractions, including wiring in or on all structures. This article is intended to apply only to temporary structures. For requirements on permanent structures, see Articles 518, 520, and 522.
I. General Requirements (525.1 through 525.6)
Part I gives definitions, provides general requirements for clearances of wiring and protection of equipment, and directs the user to other NEC articles that contain requirements for structures not covered in Article 525. For instance, water attractions, such as fountains, pools, and water slides, are covered by the applicable requirements of Article 680, and audio systems are covered by Article 640.
II. Power Sources (525.10 and 525.11)
Part II provides some of the requirements for services and multiple sources of supply that are separately derived systems, such as generators and transformers. Part II also requires that equipment that is accessible to unqualified persons be lockable, a requirement designed to protect the public visiting such temporary attractions.
III. Wiring Methods (525.20 through 525.23)
Part III includes requirements for installation, disconnecting means, and GFCI protection for wiring supplying temporary structures at carnivals, fairs, circuses, and similar attractions. Section 525.23 provides three categories: Where GFCIs are required, where they are not required, and where they are not permitted to be installed (GFCI protection is not allowed on circuits that supply illumination for a means of egress).
IV. Grounding and Bonding (525.30 through 525.32)
Part IV provides requirements for grounding and bonding of metal raceways, metal enclosures, and metal parts of equipment. Section 525.32 specifically requires that continuity of the grounding conductor system be verified each time the equipment is reconnected. Due to the transient nature of fairs and circuses, equipment tends to be disconnected, moved, and reconnected often. The
requirements in Part IV are intended to keep workers and visitors safe. | 522, 525 | |
ARTICLE 695 Fire Pumps
This article provides requirements for installation of electric power sources and interconnecting circuits and switching and control equipment dedicated to fire pump drivers. The article does not cover the internal wiring in fire pumps. The requirements of Article 695 are independent of those in Article 700 unless otherwise mandated by the authority having jurisdiction.
ARTICLE 700 Emergency Systems
This article provides requirements for emergency systems that are essential for life safety and are legally required by state, federal, or municipal regulations in the event of a loss of normal power. Essential life safety systems supplied by emergency power include exit lighting and fire alarms. Article 700 covers such emergency systems, their capacity and rating, the transfer switches and power sources necessary to these systems, and their overcurrent protection.
I. General (700.1 through 700.8)
This part covers the testing and maintenance of emergency systems, which are defined as those intended to supply illumination or power when normal electrical supply is interrupted. Also covered are transfer switches and signage for these systems.
II. Circuit Wiring (700.9)
This part gives requirements for the wiring of emergency system circuits, including the location, installation, and identification of the cables for the use.
III. Sources of Power (700.12)
The requirements in this part mandate that in the event of a failure of normal power, an emergency system must be activated within 10 seconds.
IV. Emergency System Circuits for Lighting and Power (700.15 Though 700.18)
This part provides requirements for the loads on branch circuits specifically used for lighting means of egress and providing power in an emergency.
V. Control — Emergency Lighting Circuits (700.20 Though 700.23)
This part specifies where emergency lighting and lighting switches can be located, and who should service such systems.
VI. Overcurrent Protection (700.25 Though 700.27)
Ground-fault indication of circuits is mandated by this part for emergency systems, and disconnecting means must be available.
ARTICLE 701 Legally Required Standby Systems
This article contains requirements for standby systems that are legally required by federal, state, or municipal government regulations but are not classified as “emergency.” When normal power is lost, these systems must be able to supply backup power within 60 seconds. This article covers capacity and rating, transfer switches, and generators or other power sources that allow automatic supply of power in these instances.
I. General (701.1 through 701.9)
II. Circuit Wiring (701.10)
III. Sources of Power (701.11)
IV. Overcurrent Protection (701.15 Through 701.18)
ARTICLE 702 Optional Standby Systems
This article contains requirements for standby systems that are not legally required and where life safety does not depend on performance of the system, but failure of normal supply might cause physical discomfort or serious interruption of an industrial process, damage to the process equipment, or disruption of business. Covered are permanently installed and portable generators that can be connected to an optional standby system, and the capacity, rating, grounding, wiring, and signage necessary to these systems.
I. General (702.1 through 702.8)
II. Circuit Wiring (702.9)
III. Grounding (702.10)
IV. Sources of Power (701.11)
Additional Locations
Fire Pumps
Connection at services 230.72(A) Ex., 230.82(5), 230.94, Ex. 4
Grounding 250.112(L), 250.112(M)
Overcurrent protection of motors 430.31 FPN
Remote Control circuits 430.72(B) Ex 1
Service Equipment overcurrent protection 230.90(A)
Services 230.2(A)(1)
Emergency Systems
Health Care Facilities 517.26
Service Disconnecting Means 230.72(B) | 695, 700, 701, 702 | |
Article 250: Grounding and Bonding
Article 250 covers the requirements for grounding and bonding of electrical installations. It also specifies the conditions under which guards, isolation, or insulation may be substituted for grounding.
I. General (250.1 Through 250.14)
This part describes the purpose of grounding and bonding, prevention of objectionable currents over the grounding path, effective methods for making grounding and bonding connections, and protection of ground clamps and fittings.
II. System Grounding (250.20 Through 250.36)
This part describes which systems are required to be grounded, which systems are permitted but not required to be grounded, and which systems are prohibited from being grounded.
III. Grounding Electrode System and Grounding Electrode Conductor (250.50 Through 250.70)
This part describes the requirements for grounding electrodes and grounding electrode conductors.
IV. Enclosure, Raceway, and Service Cable Connections (250.80 Through 250.86)
This part describes the requirements for grounding metal enclosures and raceways.
V. Bonding (250.90 Through 250.106)
This part describes the requirements for bonding metal parts of equipment enclosures on both grounded and ungrounded electrical systems, metal piping systems, exposed structural steel, and lightning protection systems.
VI. Equipment Grounding and Equipment Grounding Conductors (250.110 Through 250.126)
This part first describes the requirements for grounding equipment that is fixed in place or connected by permanent wiring methods. Then it describes the requirements for equipment grounding conductors.
VII. Methods of Equipment Grounding (250.130 Through 250.148)
This part describes what is required to be grounded as well as the basic properties of equipment grounding conductors. Other topics covered include the following:
• Raceway or cable armor
• Equipment fastened in place or connected by permanent wiring methods
• Equipment considered effectively grounded
• Frames of ranges and clothes dryers
• Use of a grounded circuit conductor for equipment grounding
• Connecting receptacle grounding terminals
• Isolated grounded receptacles
• Attachment of equipment grounding conductors to boxes
VIII. Direct-Current Systems (250.160 Through 250.169)
This part describes the requirements for grounding direct-current systems. However, where this part does not specifically require or prohibit an aspect of grounding dc systems, another part or section of Article 250 not specifically intended for ac systems may apply.
IX. Instruments, Meters, and Relays (250.170 Through 250.178)
This part provides the requirements for grounding devices such as current and potential transformers, meters, and relays.
X. Grounding of Systems and Circuits of 1 kV and Over (High Voltage) (250.180 Through 250.190)
This part describes the requirements for derived neutral systems, solidly grounded neutral systems, and impedance grounded neutral systems, and for grounding of systems supplying portable or mobile equipment. This includes the requirements for equipment associated with non–current-carrying metal parts of all high-voltage installations.
Additional Grounding and Bonding Requirements
|
Conductor/Equipment |
Article |
Section |
|
|
Agricultural buildings |
|
547.9 and 547.10 |
|
Audio signal processing, amplification, and reproduction equipment |
|
640.7 |
|
Branch circuits |
|
210.5, 210.6, 406.3 |
|
Cablebus |
|
370.9 |
|
Cable trays |
392 |
392.3(C), 392.7 |
|
Capacitors |
|
460.10, 460.27 |
|
Circuits and equipment operating at less than 50 volts |
720 |
|
|
Closed-loop and programmed power distribution |
|
780.3 |
|
Communications circuits |
800 |
|
|
Community antenna television and radio distribution systems |
|
820.93, 820.100, 820.103 |
|
Conductors for general wiring |
310 |
|
|
Cranes and hoists |
610 |
|
|
Electrically driven or controlled irrigation machines |
|
675.11(C), 675.12, 675.13, 675.14, 675.15 |
|
Electric signs and outline lighting |
600 |
|
|
Electrolytic cells |
668 |
|
|
Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chairlifts |
620 |
|
|
Fixed electric heating equipment for pipelines and vessels |
|
427.29, 427.48 |
|
Fixed outdoor electric deicing and snow-melting equipment |
|
426.27 |
|
Flexible cords and cables |
|
400.22, 400.23 |
|
Floating buildings |
|
553.8, 553.10, 553.11 |
|
Grounding-type receptacles, adapters, cord connectors, and attachment plugs |
|
406.9 |
|
Hazardous (classified) locations |
500–516 |
|
|
Health care facilities |
517 |
|
|
Induction and dielectric heating equipment |
665 |
|
|
Industrial machinery |
670 |
|
|
Information technology equipment |
|
645.15 |
|
Intrinsically safe systems |
|
504.50 |
|
Luminaires and lighting equipment |
|
410.40, 410.42, 410.46, 410.155(B) |
|
Luminaires, lampholders, and lamps |
410 |
|
|
Marinas and boatyards |
|
555.15 |
|
Mobile homes and mobile home park |
550 |
|
|
Motion picture and television studios and similar locations |
|
530.20, 530.64(B) |
|
Motors, motor circuits, and controllers |
430 |
|
|
Natural and artificially made bodies of water |
682 |
682.30, 682.31, 682.32, 682.33 |
|
Outlet, device, pull, and junction boxes; conduit bodies; and fittings |
|
314.4, 314.25 |
|
Over 600 volts, nominal, underground wiring methods |
|
300.50(B) |
|
Panelboards |
|
408.40 |
|
Pipe organs |
650 |
|
|
Radio and television equipment |
810 |
|
|
Receptacles and cord connectors |
|
406.3 |
|
Recreational vehicles and recreational vehicle parks |
551 |
|
|
Services |
230 |
|
|
Solar photovoltaic systems |
|
690.41, 690.42, 690.43, 690.45, 690.47 |
|
Swimming pools, fountains, and similar installations |
680 |
|
|
Switchboards and panelboards |
|
408.3(D) |
|
Switches |
|
404.12 |
|
Theaters, audience areas of motion picture and television studios, and similar locations |
|
520.81 |
|
Transformers and transformer vaults |
|
450.10 |
|
Use and identification of grounded conductors |
200 |
|
|
X-ray equipment |
660 |
517.78 |
|
|
|
|
|
| 250 | |
Chapter 5, Special Occupancies, extends the basic requirements given in Chapters 1-4 to include rules for electrical installations in specialized types of construction or vehicles. The first 12 articles of Chapter 5, Articles 500 through 516, cover electrical installations in hazardous locations. These articles apply primarily to industrial and transportation facilities where ignitible substances are manufactured or processed and to areas where flammable fuels are stored or used.
ARTICLE 500 Hazardous (Classified) Locations, Classes I, II, and III, Divisions 1 and 2
ARTICLE 501 Class I Locations
ARTICLE 502 Class II Locations
ARTICLE 503 Class III Locations
ARTICLE 504 Intrinsically Safe Systems
ARTICLE 505 Class I, Zone 0, 1, and 2 Locations
ARTICLE 506 Zone 20, 21, and 22 Locations for Combustible Dusts or Ignitible Fibers/Flyings
ARTICLE 510 Hazardous (Classified) Locations, Specific
ARTICLE 511 Commercial Garages, Repair and Storage
ARTICLE 513 Aircraft Hangars
ARTICLE 515 Bulk Storage Plants
ARTICLE 516 Spray Application, Dipping, and Coating Processes
Where to Find Hazardous Locations in Other Codes and Standards
Section 500.4(B), FPN 2 lists other codes and standards that contain further information on electrical installations in hazardous locations. These include the following:
NFPA 30-2008, Flammable and Combustible Liquids Code
NFPA 32-2007, Standard for Drycleaning Plants
NFPA 33-2007, Standard for Spray Application Using Flammable or Combustible Materials
NFPA 34-2007, Standard for Dipping and Coating Processes Using Flammable or Combustible Liquids
NFPA 35-2005, Standard for the Manufacture of Organic Coatings
NFPA 36-2004, Standard for Solvent Extraction Plants
NFPA 45-2004, Standard on Fire Protection for Laboratories Using Chemicals
NFPA 55-2005, Standard for the Storage, Use, and Handling of Compressed Gases and Cryogenic Fluids in Portable and Stationary Containers, Cylinders, and Tanks
NFPA 58-2008, Liquefied Petroleum Gas Code
NFPA 59-2004, Utility LP-Gas Plant Code
NFPA 497-2004, Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas
NFPA 499-2004, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas
NFPA 820-2008, Standard for Fire Protection in Wastewater Treatment and Collection Facilities
ANSI/API RP500-1997, Recommended Practice for Classification of Locations of Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2
ISA-12.10-1988, Area Classification in Hazardous (Classified) Dust Locations
Further information on protection against static electricity and lightning hazards in hazardous (classified) locations can be found in the following standards:
NFPA 77-2007, Recommended Practice on Static Electricity
NFPA 780-2008, Standard for the Installation of Lightning Protection Systems
API RP 2003-1998, Protection Against Ignitions Arising Out of Static Lightning and Stray Currents
Further information on ventilation can be found in the following documents:
NFPA 30-2008, Flammable and Combustible Liquids Code
API RP 500-1997, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2
Further information on electrical systems for hazardous (classified) locations on offshore oil- and gas-producing platforms can be found in ANSI/API RP 14F-1999, Recommended Practice for Design and Installation of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Division 1 and Division 2 Locations.
The NFPA and ANSI standards referenced in Articles 500 through 516 are essential for proper application of those articles. The following NFPA codes, standards, and recommended practices not listed in 500.4(B) FPN 2 include information on hazardous (classified) locations and the extent of hazardous (classified) locations in specific occupancies or industries:
NFPA 30A, Code for Motor Fuel Dispensing Facilities and Repair Garages
NFPA 51, Standard for the Design and Installation of Oxygen–Fuel Gas Systems for Welding, Cutting, and Allied Processes
NFPA 51A, Standard for Acetylene Cylinder Charging Plants
NFPA 52, Vehicular Fuel Systems Code
NFPA 54, Natural Fuel Gas Code
NFPA 59A, Standard for the Production, Storage, and Handling of Liquefied Natural Gas (LNG)
NFPA 61, Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Products Facilities
NFPA 85, Boiler and Combustion Systems Hazards Code
NFPA 88A, Standard for Parking Structures
NFPA 99, Standard for Health Care Facilities
NFPA 407, Standard for Aircraft Fuel Servicing
NFPA 409, Standard on Aircraft Hangars
NFPA 495, Explosive Materials Code
NFPA 496, Standard for Purged and Pressurized Enclosures for Electrical Equipment
NFPA 654, Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids
NFPA 655, Standard for Prevention of Sulfur Fires and Explosions | 500-516 | |
Article 90 Introduction
Article 90 is outside the nine-chapter structure of the NEC®, but it creates the basic framework for using and enforcing the Code. This short article establishes the purpose, scope, and arrangement of the Code, and it outlines the enforcement authority language and units of measurement that will be used throughout.
Article 100 Definitions
This article contains basic definitions needed to understand and use the NEC, including terms that sometimes lead to confusion in the field. The “field names” for many products are outlined, and the full product name provided to further reduce confusion. Any definition that appears in at least two other articles of the Code is defined in Article 100. More specific or specialized terms are defined in the article within which they appear (always in the second numbered section).
Article 100 is divided into two parts. Part I covers general definitions, and Part II covers definitions specific to systems over 600 volts, nominal.
Article 110 Requirements for Electrical Installations
Article 110 provides general requirements that apply to most electrical installations. The first part describes the key concepts of installation, approval, flash protection, and the concept of “neat and workmanlike.” The remaining three parts break down requirements into those for installations of 600 volts or less, installations over 600 volts, and tunnel installations over 600 volts.
The notion of “neat and workmanlike” is one of the most discussed provisions of the Code, because it is rather undefined and yet recurrent. Other places where references to “neat and workmanlike” can be found in the NEC are the following:
Article 110, Requirements for Electrical Installations 110.12
Article 640, Audio Signal Processing, Amplification,
and Reproduction Equipment 640.6, 640.22, and 640.43
Article 720, Circuits and Equipment Operating at Less Than 50 Volts 720.11
Article 725, Class 1, Class 2, and Class 3 Remote Control,
Signaling, and Power-Limited Circuits 725.24
Article 760, Fire Alarm Systems 760.24
Article 770, Optical Fiber Cables and Raceways 770.24
Article 800, Communications Circuits 800.24
Article 820, CATV and Radio Distribution Systems 820.24
Article 830, Network-Powered Broadband Communication Systems 830.24
| 90, 100, 110 | |
ARTICLE 725 Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits
Article 725 covers requirements for remote-control, signaling, and power-limited circuits operating at various voltage and power levels.
I. General (725.1 through 725.35)
This part defines Class 1, 2, and 3 circuits and outlines requirements for safety and protection of circuits.
II. Class 1 Circuits (725.41 through 725.52)
This part offers requirements for protection of Class 1 circuits, including location of overcurrent devices, installation of cables in trays and raceways, and insulation of conductors.
III. Class 2 and Class 3 Circuits (725.121 through 725.154)
This part offers requirements for Class 2 and 3 circuits, their interconnection with one another and with Class 1 circuits, as well as their installation and use in different locations.
IV. Listing Requirements (725.179)
This part offers requirements for listing and marking of cables as fire resistant and suitable for use. Table 725.179 specifies listed cable types and their markings.
ARTICLE 760 Fire Alarm Systems
Article 760 covers the installation of wiring and equipment for fire alarm systems.
I. General (760.1 through 760.35)
This part introduces and defines some useful terms for the installation and protection of fire alarm systems. It also references NFPA 72, National Fire Alarm Code for information on the subject.
II. Non–Power-Limited Fire Alarm (NPLFA) Circuits (760.41 through 760.53)
Non–power-limited fire alarm (NPLFA) circuits generally use Chapter 3 wiring methods, but this part gives specific guidelines for conductor installation and materials and wiring of NPLFA systems.
III. Power-Limited Fire Alarm (PLFA) Circuits (760.121 through 760.154)
Power-limited fire alarm circuits (PLFA) are generally a Class 3 wiring method, but this part gives specific requirements for the installation and protection of wiring and materials for PLFA systems.
IV. Listing Requirements (760.176 and 760.179)
This part provides requirements for sizing conductors, and for listing and marking of cables in fire alarm circuits and their associated systems. Table 760.179(I) lists cable types and their markings.
ARTICLE 770 Optical Fiber Cables and Raceways
Article 770 covers installation, protection, and listing of optical fiber cables and raceways and provides rules for installing fiber optic communications systems within buildings and similar structures. This article does not cover the construction of optical fiber raceways or cables.
I. General (770.1 through 770.26)
II. Cables Outside and Entering Buildings (770.48)
III. Protection (770.93)
IV. Grounding Methods (770.100 and 770.106)
V. Installation Methods Within Buildings (770.110 through 770.154)
VI. Listing Requirements (770.179 and 77.182)
ARTICLE 800 Communications Circuits
Article 800 covers telephone, telegraph, and outside wiring for fire alarm and burglar alarm systems connected to a central station. This article also covers computer networks installed using telephone-type twisted-pair cabling (Categories 3, 5, 5E, and 6). Such networks are considered by applicable industry standards to be a subset of telecommunications.
I. General (800.1 through 800.26)
II. Wires and Cables Outside and Entering Buildings (800.44 through 800.53)
III. Protection (800.90 and 800.93)
IV. Grounding Methods (800.100 and 800.106)
V. Installation Methods Within Buildings (800.110 through 800.156)
VI. Listing Requirements (800.170 through 800.182)
ARTICLE 820 Community Antenna Television and Radio Distribution Systems
Article 820 covers distribution of radio frequency signals by means of coaxial cable. Although the title refers to community antenna television (CATV) systems, its rules are also used for other types of systems wired with coaxial cable, including closed-circuit television and some computer networks.
I. General (820.1 through 820.26)
II. Coaxial Cables Outside and Entering Buildings (820.44 through 820.48)
III. Protection (820.93)
IV. Grounding Methods (820.100 and 820.106)
V. Installation Methods Within Buildings (820.110 through 820.154)
VI. Listing Requirements (820.179 and 820.182)
ARTICLE 830 Network-Powered Broadband Communications Systems
Article 830 covers broadband communications systems that deliver voice, audio, video, data, and interactive services by means of coaxial cable, with operating power delivered by means of the solid center conductor. Major concerns of Article 830 include power levels, cable types, and bonding and grounding.
I. General (830.1 through 830.24)
II. Cables Outside and Entering Buildings (830.40 through 830.47)
III. Protection (830.90 through 830.93)
IV. Grounding Methods (830.100 and 830.106)
V. Installation Methods Within Buildings (830.110 through 830.160)
VI. Listing Requirements (830.179)
| 725, 760, 770, 780, 800, 820, 830 | |
ARTICLE 220 Branch-Circuit, Feeder, and Service Calculations
A critical part of the Code, Article 220 provides calculation methods for computing branch-circuit, feeder, and service loads. Calculations performed according to the requirements of Article 220 provide the basis for sizing services; sizing and selecting distribution equipment such as panelboards, disconnect switches, and transformers; sizing feeder and branch-circuit conductors; determining how many branch circuits are required; and deciding how much load including how many lighting outlets and receptacle outlets can be placed on a branch circuit.
I. General (220.1 through 220.5)
Part I provides general rules for calculating loads. Figure 220.1 outlines which sections of Article 220 to reference for which types of loads. Table 220.3 provides a list of other sections of the NEC to reference for load calculations.
II. Branch-Circuit Load Calculations (220.10 through 220.18)
Part II provides rules for calculating specific types of loads that might be put on a branch circuit, from electric dryers to lighting to multioutlet assemblies.
III. Feeder and Service Load Calculations (220.40 through 220.61)
Part III provides the requirements for calculating the service and feeder loads. It supplies tables of load demand factors that must be applied in determining the load for lighting, receptacle loads in other than dwelling units, household electric clothes dryers, and household cooking appliances over 1¾ kW rating. Branch circuits need to be sized to carry their connected load but the load diversity provided in the Tables of Part III make it possible to size the feeders and service less than the sum of all the branch circuit ampacities.
IV. Optional Feeder and Service Load Calculations (220.80 through 220.88)
Part IV contains optional rules for calculating the load of dwelling units, existing dwelling units, multiple dwelling units, restaurants and schools.
V. Farm Load Calculations (220.100 through 220.103)
This short part is for farm loads. A typical farm served by a single service includes both a dwelling unit and an agricultural building or buildings with commercial-industrial type equipment, so the rules governing load calculation must take into account a combination load.
Where to Find Branch-Circuit, Feeder, and Service Calculation Methods in Article 220
Additional References for Load Calculation
|
Calculation |
Article |
Section (or Part) |
|
Air-conditioning and refrigerating equipment, branch-circuit conductor sizing |
440 |
Part IV |
|
Cranes and hoists, rating and size of conductors |
610 |
610.14 |
|
Electric welders, ampacity calculations |
630 |
630.11, 630.31 |
|
Electrically driven or controlled irrigation machines |
675 |
675.7(A), 675.22(A) |
|
Electrified truck parking spaces |
626 |
|
|
Electrolytic cell lines |
668 |
668.3(C) |
|
Electroplating, branch-circuit conductor sizing |
669 |
669.5 |
|
Elevator feeder demand factors |
620 |
620.14 |
|
Fire pumps, voltage drop (mandatory calculation) |
695 |
695.7 |
|
Fixed electric heating equipment for pipelines and vessels, branch-circuit sizing |
427 |
427.4 |
|
Fixed electric space-heating equipment, branch-circuit sizing |
424 |
424.3 |
|
Fixed outdoor electric deicing and snow-melting equipment, branch-circuit sizing |
426 |
426.4 |
|
Industrial machinery, supply conductor sizing |
670 |
670.4(A) |
|
Marinas and boatyards, feeder and service load calculations |
555 |
555.12 |
|
Mobile homes, manufactured homes, and mobile home parks, total load for determining power supply |
550 |
550.18(B) |
|
Mobile homes, manufactured homes, and mobile home parks, allowable demand factors for park electrical wiring systems |
550 |
550.31 |
|
Motion picture and television studios and similar locations, sizing of feeder conductors for television studio sets |
530 |
530.19 |
|
Motors, feeder demand factor |
430 |
430.26 |
|
Motors, multimotor and combination-load equipment |
430 |
430.25 |
|
Motors, several motors or a motor(s) and other load(s) |
430 |
430.24 |
|
Over 600-volt branch-circuit calculations |
210 |
210.19(B) |
|
Over 600-volt feeder calculations |
215 |
215.2(B) |
|
Phase converters, conductors |
455 |
455.6 |
|
Recreational vehicle parks, basis of calculations |
551 |
551.73(A) |
|
Sensitive electrical equipment, voltage drop (mandatory calculation) |
647 |
647.4(D) |
|
Solar photovoltaic systems, circuit sizing and current |
690 |
690.8 |
|
Storage-type water heaters |
422 |
422.11(E) |
|
Theatres, stage switchboard feeders |
520 |
520.27 | | 220 | |
Article 410 Luminaires, Lampholders, and Lamps
Article 410 covers various types of lighting equipment and installations, from electric discharge lamps to decorative lighting and accessories. (See Article 600 for coverage of sign and outline lighting.)
I. General (410.1 Through 410.8)
This Part provides an overview and definitions. Section 410.5 requires that luminaires and lampholders have no live parts normally exposed to contact. Section 410.6 requires that all luminaries and lampholders be listed.
II. Luminaire Locations (410.10 Through 410.18)
This Part covers installation requirements for specific locations, such as bathtub and shower areas or show windows. It contains requirements protecting against ignition of combustible materials, and protecting against shock hazard.
III. Provisions at Luminaire Outlet Boxes, Canopies, and Pans (410.20 Through 410.24)
Sections 410.20 through 410.24 deal with space for conductors, temperature limits, outlet box coverings, and protection of combustible wall or ceiling finishes. Special requirements for connecting and accessing electric-discharge luminaires are contained in 422.24.
IV. Luminaire Supports (410.30 Through 410.36)
This Part covers support of luminaires by outlet boxes, metal poles, suspended ceiling systems, and trees. Section 410.30(B) provides the conditions under which metal poles are permitted to contain conductors or support luminaires.
V. Grounding (410.40 Through 410.46)
This Part requires that exposed metal parts of fixtures be connected to an equipment grounding conductor, insulated from the equipment grounding conductor, or inaccessible to unqualified personnel. It also references other NEC sections where one can find requirements for such grounding.
VI. Wiring of Luminaires (410.48 Through 410.68)
Most of this Part deals with the wiring of fixtures themselves, rather than with branch-circuit wiring methods to supply luminaires. However, 410.64 permits luminaires to be used as raceways for circuit conductors, provided the luminaires are listed and marked for that purpose.
VII. Construction of Luminaires (410.70 Through 410.86)
This part deals with the design, materials, ratings, mechanical strength, and marking of luminaries, including portable luminaires.
VIII. Installation of Lampholders (410.90 Through 410.96)
This Part outlines the requirements for installation of lampholders. Section 410.90 requires that lampholders of the screw shell type be installed for use as lampholders only, to prohibit the use of lamp-socket adapters that contain nongrounding-type receptacles.
IX. Construction of Lampholders (410.100 and 410.102)
This part requires that lampholders be insulated and constructed so that on/off switching occurs in the phase conductor, which is connected to the center contact.
X. Lamps and Auxiliary Equipment (410.103 and 410.104)
This Part permits high-wattage incandescent lamps to be installed only in luminaires specifically designed for them. Ballasts of electric-discharge lighting that operates at 240 or 480 volts are required to have switching devices that simultaneously disconnect all conductors.
XI. Special Provisions for Flush and Recessed Luminaires (410.110 Through 410.117)
This Part covers temperature, clearance, and installation requirements for flush and recessed luminaries, so as not to expose surrounding combustible building materials to unsafe temperatures.
XII. Construction of Flush and Recessed Luminaires (410.118 Through 410.122)
According to this Part, luminaires must not expose surrounding combustible building materials to unsafe temperatures and must themselves be constructed to resist harmful effects of high temperatures.
XIII. Special Provisions for Electric-Discharge Lighting Systems of 1000 Volts or Less (410.130 Through 410.139)
This part requires that luminaires be installed in such a way that they don't expose surrounding combustible building materials to unsafe temperatures. One common protective technique outlined is the use of thermally protected ballasts that automatically disconnect themselves if their temperatures exceed a pre-set limit.
XIV. Special Provisions for Electric-Discharge Lighting Systems of More than 1000 Volts (410.140 Through 410.147)
This part covers electric-discharge lighting for general illumination operating at a supply voltage of 1000 to 7500 volts to ground. High-voltage electric-discharge luminaires are not permitted to be used in or on dwelling occupancies and must be marked with their operating voltage.
XV. Lighting Track (410.151 Through 410.155)
This Part covers construction, installation, and permitted locations for lighting track. Lighting track fittings are not permitted to contain general-purpose receptacles, but may have receptacles intended for the connection of track lighting heads. Lighting track connected load varies with the number of lighting heads installed.
XVI. Decorative Lighting and Similar Accessories (410.160)
This Part requires that decorative lighting and accessories, such as holiday lights, be listed in accordance with 590.3(B).
ARTICLE 411 Lighting Systems Operating at 30 Volts or Less
Article 411 is not divided into parts.
Article 411 covers listing, assembly, location, and insulation of lighting systems and their associated components that operate at 30 volts or less. Lighting systems covered by the rules of Article 411 can be those in both outdoor locations such as pools or fountains, and those in indoor locations used as decorative or accent lighting.
Other Locations
portable arc lamps 520.61, 530.17
near bathtubs or showers 551.53(B)
branch circuit computation, size, voltage 210.6, 210.19(A), 210.23,
220.12, 220.14, 220.18
no-niche luminaries 680.23(D), 680.24(B), 680.26(B)(4)
overcurrent protection of wires and cords 240.5
installation near swimming pools and spas 680.22(C), 680.23, 680.26(B)(4),
680.33, 680.43(B), 680.51, 680.62(F), 680.72
wet-niche luminaries 680.23(B)
dry-niche luminaries 680.23(C)
infrared lamp industrial heating appliances 422.14, 422.48
incandescent lamps 404.14(B)(3), 511.7(B), 513.7(C), 520.72
fluorescent luminaries 210.23, 220.18(B), 240.83,
404.14(A)(1), 404.14(B)(2)
| 410, 411 | |
ARTICLE 430 Motors, Motor Circuits, and Controllers
Article 430 is one of the longest and most complex in the Code because the equipment it covers is complex and varied. Electric motors are manufactured in many different types, with different operating characteristics suited to different applications. Motor controllers are a complex topic because most types of motors have high starting currents, which complicates overcurrent protection: Devices must be set at ampere levels high enough to permit starting but low enough to ensure normal operation. Further complicating the subject is the fact that, although most electrical equipment is rated in volt-amperes, motors are traditionally rated in horsepower. The tables at the end of this article provide conversion of motor horsepower ratings into amperes for full-load currents and locked-rotor currents.
I. General (430.1 through 430.18)
Part I covers definitions; current ratings; design letters on nameplates; dust protection of motors; marking of terminals; construction, dimensions, and wire-bending spaces for controllers; and the protection of motors and controllers by enclosures and housings.
II. Motor Circuit Controllers (430.21 through 430.29)
Part II specifies sizes of circuit conductors for motors operating at 600 volts and below. Factors that can affect conductor size include whether the branch circuit serves a single motor, multiple motors, or a combination load; the duty factor of the motor; and feeder demand factors where not all loads on a branch circuit operate at the same time.
III. Motor and Branch-Circuit Overload Protection (430.31 through 430.44)
Part III contains requirements for motor overload protection, defined as operating overcurrent that can cause dangerous overheating if allowed to continue.
IV. Motor Branch-Circuit Short-Circuit and Ground-Fault Protection (430.51 through 430.58)
Part IV specifies the devices for protecting motor branch-circuit conductors, motor controllers, and motors from the effects of ground faults and short circuits. As stated in 430.51, these devices are not the same as GFCI protection for personnel, GFPE, or the assured equipment grounding conductor program (AEGCP) required in other parts of the Code.
V. Motor Feeder Short-Circuit and Ground-Fault Protection (430.61 through 430.63)
This short part deals with overcurrent protection of feeder conductors supplying motor loads.
VI. Motor Control Circuits (430.71 through 430.75)
Part VI provides rules for the overcurrent protection, mechanical protection, and disconnecting means of motor control circuit conductors.
VII. Motor Controllers (430.81 through 430.90)
Part VII deals with the safe construction and operation of motor controllers and defines control characteristics for different types of motors intended to ensure their safe operation. Accurate speed control, for instance, allows for the smooth acceleration and braking essential for such devices as electric railways and elevators.
VIII. Motor Control Centers (430.92 through 430.98)
Part VIII contains rules for motor control centers, which are assemblies containing motor controllers. They also can contain branch-circuit protective devices for lighting and power circuits. In some ways, motor control centers are similar to switchboards and are permitted to serve as service entrance equipment. For that reason, some of the rules for motor control centers found in this part are similar to those for switchboards found in Article 408.
IX. Disconnecting Means (430.101 through 430.113)
Part IX covers permitted types of disconnects and controllers for different types of motors. In general, the disconnecting means for motor circuits operating at 600 volts or less is required to have an ampere rating at least 115 percent of the full-load current rating of the motor.
X. Adjustable-Speed Drive Systems (430.120 through 430.128 )
Part X outlines the overload and overtemperature protections and disconnecting means required for adjustable-speed drive systems. It also gives the size and ampacity allowed for circuit conductors supplying adjustable-speed drive systems.
XI. Over 600 Volts, Nominal (430.221 through 430.227)
Part XI provides extra requirements for high-voltage motors that supplement or amend the other provisions of Article 430, including provisions for overload and fault-current protection and disconnecting means.
XII. Protection of Live Parts — All Voltages (430.231 through 430.233)
Part XII introduces the requirement that exposed live parts be guarded against accidental contact by enclosures by being located in areas accessible only to qualified persons or by providing insulated mats and platforms for personnel adjusting or maintaining the motors.
XIII. Grounding — All Voltages (430.241 through 430.245)
Part XIII covers the general requirement that exposed non–current-carrying metal parts of motors, controller frames, and controller enclosures be grounded. Insulation, isolation, and guarding are suitable alternatives under certain conditions. Motor junction boxes are permitted to be separated from motors by up to 6 feet if they are connected to motors by metallic cable or raceway wiring methods.
XIV. Tables
The six tables that make up Part XIV are probably the most widely used segment of Article 430. Tables 430.247 through 430.250 are used in selecting motor circuit conductors. Tables 430.251(A) and (B) are used to select motor disconnecting means and controllers.
Table 430.5 Other Articles
|
Equipment/Occupancy |
Article |
Section |
|
Air-conditioning and refrigerating equipment |
440 |
|
|
Capacitors |
|
460.8, 460.9 |
|
Commercial garages; aircraft |
511, 513, |
|
|
hangars; motor fuel dispensing facilities; bulk storage plants; spray application, dipping, and coating processes; and inhalation anesthetizing locations |
514, 515, 516, and 517 Part IV |
|
|
Cranes and hoists |
610 |
|
|
Electrically driven or controlled irrigation machines |
675 |
|
|
Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts |
620 |
|
|
Fire pumps |
695 |
|
|
Hazardous (classified) locations |
500–503 and 505 |
|
|
Industrial machinery |
670 |
|
|
Motion picture projectors |
|
540.11 and 540.20 |
|
Motion picture and television studios and similar locations |
530 |
|
|
Resistors and reactors |
470 |
|
|
Theaters, audience areas of motion picture and television studios, and similar locations |
|
520.48 |
|
Transformers and transformer vaults |
450 |
|
Figure 430.1 Article 430 Contents
| 430 | |
ARTICLE 225 Outside Branch Circuits and Feeders
This article covers most permanent outdoor installations of wiring, equipment, and lighting using wiring methods described in Chapter 3. Lighting installations covered by this article are hard wired and intended to remain in place for an extended period of time.
I. General (225.1 through 225.26)
Major subjects covered by Part I include: Conductor types and sizes and voltage ratings; mechanical protection and support of conductors, raceways, and equipment; clearances between conductors and buildings, roadways, walkways, rail lines, and waterways; and pendant and festoon lighting.
II. More than One Building or Other Structure (225.30 through 225.40)
This part contains requirements for all kinds of structures that might support outdoor branch circuits (farm buildings, pumping stations, electric signs, and towers or poles used as lighting standards), including requirements for disconnects.
III. Over 600 Volts (225.50 through 225.61)
Installations covered by this part are most often industrial facilities, as these installations tend to be at higher voltage and require larger clearances for safety. This part refers readers to ANSI/IEEE C2, National Electrical Safety Code 2007, for additional information on installations over 600 volts.
Other Locations — Outside Branch Circuits and Feeders
|
Equipment/Conductors |
Article |
|
Branch circuits |
210 |
|
Class 1, Class 2, and Class 3 remote-control, |
|
|
signaling, and power-limited circuits |
725 |
|
Communications circuits |
800 |
|
Community antenna television and radio distribution |
820 |
|
Conductors for general wiring |
310 |
|
Electrically driven or controlled irrigation machines |
675 |
|
Electric signs and outline lighting |
600 |
|
Feeders |
215 |
|
Fire alarm systems |
760 |
|
Fixed outdoor electric deicing and snow-melting equipment |
426 |
|
Floating buildings |
553 |
|
Grounding |
250 |
|
Hazardous (classified) locations |
500 |
|
Hazardous (classified) locations — specific |
510 |
|
Marinas and boatyards |
555 |
|
Messenger-supported wiring |
396 |
|
Mobile homes, manufactured homes, and mobile home parks |
550 |
|
Open wiring on insulators |
398 |
|
Over 600 volts, general |
490 |
|
Overcurrent protection |
240 |
|
Radio and television equipment |
810 |
|
Services |
230 |
|
Solar photovoltaic systems |
690 |
|
Swimming pools, fountains, and similar installations |
680 |
|
Use and identification of grounded conductors |
200 |
ARTICLE 230 Services
This article covers service conductors and service equipment (that is, the equipment upstream of the branch circuits and feeders that are covered by Article 225). A service is defined as the conductors and equipment for delivering electric energy from the serving utility to the wiring system of the premises served.
I. General (230.1 through 230.10)
This part outlines the number of services required and permitted under varying circumstances, and includes a general prohibition against supplying one building or structure through another.
II. Overhead Service-Drop Conductors (230.22 through 230.29)
This part provides requirements for insulation, size, rating, clearances, means of attachment, and support of overhead service-drop conductors, or conductors that extend from a pole to a building.
III. Underground Service-Lateral Conductors (230.30 through 230.33)
This part covers insulation, size, rating and protection against damage for buried service-lateral conductors that extend from a pad- or vault-mounted transformer to a building.
IV. Service-Entrance Conductors (230.40 through 230.56)
This part covers such topics as number of sets of service entrance conductors required and permitted under various circumstances, insulation, size and rating, wiring methods permitted, service heads, and protection of the conductors against water.
V. Service Equipment—General (230.62 and 230.66)
This short part contains the requirement that service equipment be either enclosed or guarded to prevent accidental contact with energized parts. It also requires service equipment rated at 600 volts or less to be marked to identify it as “suitable for use as service equipment.”
VI. Service Equipment—Disconnecting Means (230.70 through 230.82)
This part covers location and accessibility of service disconnecting means, maximum number and grouping of disconnects, ratings, and strict limitations on what equipment can be connected to the supply side of service equipment ahead of the overcurrent protection.
VII. Service Equipment—Overcurrent Protection (230.90 through 230.95)
This part requires that service equipment be protected by either circuit breakers or fuses, and provides requirements for alternative protection means under particular circumstances.
VI. Services Exceeding 600 Volts, Nominal (230.200 through 230.212)
This part covers service-entrance conductors, disconnecting means, short-circuit and overcurrent protection, and surge arresters operating at higher voltages. It also refers to transformer vault requirements in Article 450 and to service equipment provisions in Article 490.
Services
| 225, 230 | |
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 be 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.
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 |
| |
|
| | | |