Terminology and Definitions
– Neutral wire is the return conductor of a circuit.
– The neutral wire is connected to earth ground at only one point.
– The neutral is connected to the center tap of the power company transformer.
– The neutral is called the grounded conductor.
– Hot refers to any line or neutral conductor with electric potential.
– An outlet is defined as a point in the wiring system at which current is taken to utilization equipment.
– The definition includes receptacles, lighting, motors, etc.
– Ordinary switches control but do not consume electricity and are not defined as outlets.
Electrical Codes and Standards
– The National Electrical Code (NEC) specifies minimum acceptable wiring methods and materials.
– The NEC is sponsored by the National Fire Protection Association (NFPA).
– Local jurisdictions usually adopt the NEC or another published code.
– The purpose of the NEC is to protect persons and property from hazards.
– New construction, additions, or major modifications must follow the relevant code for that jurisdiction.
– GFCI protection is required for outlets in wet areas and basements.
– Two-wire outlets without grounding must be protected by a GFCI.
– AFCI protection is required for most finished areas of a home.
– Dedicated circuits are necessary for certain appliances.
– Electrical boxes must be sized correctly according to the number of wires and devices.
Design and Installation Conventions
– Terminals for the neutral conductor are required to be substantially white in color.
– Edison-base lamp sockets are required to have the neutral conductor attached to the outer screw shell.
– The neutral terminal is usually silver colored.
– The phase wire in a circuit may be any color other than green, gray, or white.
– The neutral wire is identified by gray or white insulated wire.
Grounding
– The grounding wire of a circuit may be bare or identified insulated wire of green or green having yellow stripes.
– All metallic systems in a building are to be bonded to the building grounding system.
– Larger wires are generally furnished only in black and may be re-identified with suitable paint or tape.
– All wiring in a circuit must be of the required gauge or larger.
– Ground-fault circuit interrupter (GFCI) protection is required in wet locations and areas where fault current can travel to earth.
– US wiring systems require a separate grounding conductor.
– Portable appliances with metal cases also have a bonding conductor.
– The circuit return conductor (neutral) is only connected to ground at the service entrance panel.
– Grounding practices in the US differ from regulations in other parts of the world.
– Grounding ensures the safety of electrical installations.
International Adoption and Wire Types
– Some countries adopt the NFPA standard as their national electrical code.
– The Canadian Electrical Code is similar to the US NEC with minor variations.
– Harmonization of the CEC and NEC codes facilitates free trade between Canada and the US.
– National and regional variations in wiring systems remain in effect.
– Technical standards for wiring devices, materials, and equipment also impact safety.
– Heavy duty outdoor electrical wire
– XHHW insulation is commonly used in commercial, institutional, and industrial buildings
– XHHW-2 insulation is similar to XHHW and suitable for dry or wet locations
– THWN insulation is commonly used in AC electrical distribution systems throughout North America
– THHN insulation is suitable for dry and damp locations Source: https://en.wikipedia.org/wiki/Electrical_wiring_in_North_America
Electrical wiring in North America follows the regulations and standards applicable at the installation location. It is also designed to provide proper function, and is also influenced by history and traditions of the location installation.
The US National Electrical Code is applicable to many areas in the US where state, county or local authorities have adopted it. For electrical wiring in Canada, the Canadian Electrical Code is a very similar standard published in Canada by the Canadian Standards Association.
