Electrical code is the strict set of rules that all electricians abide by on the job. It is also the basis for the journeyman and master electrician exams that electrical tradesmen take as they graduate through the different licensing levels.
Electrical code represents the established set of standards and practices that must by followed when running wire and making connections in various settings and applications, including what materials are acceptable, what kinds of redundancies need to be in place, and what methods and protocols must be followed to get it all done.
More than anything, electrical code is all about safety, ensuring that electrical installations are performed with the kind of diligence, care and attention to detail required to ensure:
- People using electrical systems and appliances in their homes and work places aren’t at risk of shock
- Buildings that electrical systems are installed in aren’t at risk of catching fire
- Electricians performing installations and those that may upgrade or make alterations to the system many years down the road are safe
Though different states and even smaller city and county-level regulatory agencies may have their own specialized amendments and additions to the electrical code used in buildings within their jurisdiction, the overarching standards of practice and materials that all jurisdictions require are set through a small group of national and international safety standards agencies.
There are three main bodies that set and maintain standards for national and international electrical code, publishing them in comprehensive books for electricians, contractors, construction inspectors and other industry regulators to reference:
- National Fire Protection Association (NFPA)
- National Electrical Code (NEC)
- Institute of Electrical and Electronics Engineers (IEEE)
- National Electrical Safety Code (NESC)
- International Code Council (ICC)
- International Building Code (IBC)
- International Fire Code (IFC)
- International Energy Conservation Code (IECC)
National Fire Protection Association (NFPA): The National Electrical Code (NEC)
The National Fire Protection Association (NFPA) established the National Electrical Code (NEC) as a standard for electrical safety in residential, commercial, and industrial buildings. As the national benchmark for the safe installation of electrical wiring and equipment, the American National Standards Institute (ANSI) also recognizes the NEC.
The NEC has been adopted in all 50 states as the benchmark for ‘safe electrical design, installation, and inspection to protect people and property from electrical hazards.’
The NFPA has been compiling the expert opinions of industry professionals – including electricians, firefighters, accident investigators, academics, and technology representatives – into one code source since 1897. The NFPA periodically comes out with new editions of the NEC, with the next one scheduled for 2017.
As an example of the changing environment master electricians constantly face, the 2017 edition is expected to include new information about large-scale photovoltaic electric supply stations and direct-current microgrids.
These are the main topics covered in the current (2014) version of the NEC:
Wiring and Protection
- Inside/outside branch circuits and feeders, and service calculations
- Service conductors
- Overcurrent protection
- Circuit breakers
- Cartridge fuses and fuseholders
- Grounding and bonding
- Surge arresters over 1,000 volts
- Surge protective devices for 1,000 volts or less
Wiring Methods
- Conductors for general wiring
- Cabinets, meter socket enclosures, and cutout boxes
- Outlet, device, junction boxes, pull, conduit bodies, handhole enclosures, and fittings
- AC armored cable
- FC flat cable assemblies
- FCC flat conductor cables
- Integrated gas spacer cable
- MV medium voltage cable
- MC metal clad cable
- MI mineral insulated metal sheathed cable
- NM, NMC, and NMS nonmetallic sheathed cable
- TC power and control tray cable
- Types of conduit and tubing
- Auxiliary gutters
- Busways
- Floor raceways and other types of raceways
- Wireways
- Low voltage suspended ceiling power distribution systems
Equipment for General Use
- Flexible cords and cables
- Fixture wires
- Switches
- Switchboards, switchgear, and panelboards
- Industrial control panels
- Luminaries, lampholders and lamps
- Appliances
- Fixed electric space heating and outdoor deicing equipment
- Fixed electric heating equipment for pipelines and vessels
- Motors, motor circuits, and controllers
- Air conditioning and refrigerating equipment
- Generators
- Transformers and transformer vaults
- Phase converters
- Capacitors
- Resistors and reactors
- Storage batteries
- Equipment over 1,000 volts
Special Occupancies
- Hazardous locations, classes, and divisions
- Intrinsically safe systems
- Commercial garages, repair, and storage
- Aircraft hangars
- Motor fuel dispensing facilities
- Bulk storage plants
- Spray application, dipping, and coating
- Health care facilities
- Assembly occupancies
- Theaters and audience areas
- Control systems for permanent amusement attractions
- Carnivals, circuses, and fairs
- Motion picture and television studios
- Manufactured buildings
- Agricultural buildings
- Mobile homes, manufactured homes, and mobile home parks
- Recreational vehicles and their parks
- Park trailers
- Floating buildings
- Marinas and boatyards
- Temporary installations
Special Equipment
- Electric signs and outline lighting
- Manufactured wiring systems
- Office furnishings
- Cranes and hoists
- Elevators, escalators, moving walks, and dumbwaiters
- Electric vehicle charging system
- Electrified truck parking spaces
- Electric welders
- Audio signal processing, amplification, and reproduction equipment
- Information technology equipment
- Modular data centers
- Sensitive electronic equipment
- Pipe organs
- X-ray equipment
- Induction and dielectric heating equipment
- Electrolytic cells and electroplating
- Industrial machinery
- Integrated electrical systems
- Solar voltaic systems
- Fuel cell systems
- Wind electric systems
- Fire pumps
Special Conditions
- Emergency systems
- Legally required standby systems
- Optional standby systems
- Interconnected electric power production sources
- Critical operations power systems
- Circuits and equipment operating at less than 50 volts
- Optical fiber cables and raceways
Communication Systems
- Communication circuits
- Radio and television equipment
- Community antenna television and radio distribution systems
- Network-powered broadband communication systems
- Premises-powered broadband communications systems
Tables and Appendices
- Cross section of conduit and tubing for conductors and cables
- Radius of conduit and tubing bends
- AC resistance and reactance for 600-volt cables
- Conductor stranding
- PLFA AC/DC power source limitations
- Product safety standards
- Ampacity calculation
- Availability and reliability for critical operations power systems
A full, unabridged version of the NEC can be purchased from NFPA, however, you can get a good idea of the contents of the NEC by consulting the NFPA’s 922-page proposed draft of the 2014 Edition of the National Electrical Code (NEC).
Institute of Electrical and Electronics Engineers (IEEE): National Electrical Safety Code (NESC)
The Institute of Electrical and Electronics Engineers’ (IEEE) National Electrical Safety Code (NESC) (publicly available 2007 version) has been adopted in full or part by most states, except California
This several-hundred-page code is revised every five years and covers the safety measures electricians must take when installing, maintaining, and operating electrical supply systems and their associated components. After the NEC, it is perhaps the most widely implemented code.
The NESC is divided into four parts, with the first being of primary relevance for electricians. The other three sections cover installing overhead lines, installing underground lines, and the operation/maintenance of these line systems.
The first part of this code covers the following subjects:
- Grounding methods for electric communications and supply facilities
- Grounding DC systems
- Grounding AC systems
- Grounding conductors and means of connection
- Grounding electrodes
- Ground resistance requirements
- Installing and maintaining electric equipment and supply stations
- Protective arrangements in electric supply stations
- Installation and maintenance of equipment
- Working with rotating equipment
- Storage batteries
- Transformers and regulators
- Conductors
- Circuit breakers, fuses, reclosers, and switches
- Surge arresters
International Code Council (ICC): International Building Code (IBC), International Fire Code (IFC), International Energy Conservation Code (IECC)
The International Code Council (ICC) has been developing comprehensive national model construction codes since 1994. In the span of just over two decades today all 50 states and the District of Columbia have adopted some of the ICC’s codes at a local and/or state level.
The International Code Council publishes three internationally recognized code standards relevant to the electrical trade:
- International Building Code (IBC)
- International Fire Code (IFC)
- International Energy Conservation Code (IECC)
International Building Code (IBC) – Adopted in all 50 states
- Emergency and standby power systems installations
- Stationary generators
- Load transfer from primary to backup power systems
- Minimum duration of backup power systems
- Systems that require an uninterrupted source of power
- Acceptable power sources for emergency power systems
- Essential electrical systems and group occupancies
- General power requirements
- Emergency alarm systems
- Power requirements for elevators and platform lifts
- Power for emergency responder radio coverage systems
- Power for emergency voice and alarm systems
- Emergency power for exit signs
- Emergency power for power-operated locking systems
- Standby power for high-rise buildings
- Standby power for smoke control systems
- Cables for critical circuits
International Fire Code (IFC) – Adopted in all states except Florida, Hawaii, Maine, Maryland, Massachusetts, Rhode Island, Vermont, and West Virginia
Key chapters in the IFC that relate to electrical work are:
Chapter 6 – Building Services and Systems:
- Battery systems and types
- Critical circuitry
- Emergency power systems
- Standby power systems
- Electrical wiring and equipment
- Abatement of electrical hazards
- Electrical motors
- Temporary wiring
- Portable electric space heaters
- Power supply
- Extension cords
- Solar photovoltaic power systems
Chapter 9 – Fire Protection Systems:
- Electrical wiring for fire protection systems
- Power supply for fire protection systems
- Electrical circuit protective systems
International Energy Conservation Code (IECC) – Adopted in all states except California, Indiana, Minnesota, and Oklahoma
Key chapters in the IECC that relate to electrical work are:
Chapter 4 – Residential Energy Efficiency, pertaining to:
- Electrical power and lighting systems
- Electrical heating and cooling systems
Chapter 4 – Commercial Energy Efficiency, pertaining to:
- Electrical power and lighting systems
- Electrical heating and cooling systems
- Electrical motors
- Electrical transformers