The list of rules to be followed when installing new electrical systems into a building are related to the specific rules of the state, as well as certain minimum requirements laid down by Federal law. So in some senses the United States does not have a unified Electrical Building Code, because often there are variations between different states.
It was to address exactly this issue that the National Fire Protection Association, a panel of nineteen different bodies, began publishing the National Electrical Code (NEC) in 1897, and now every three years, in order to arrive at a single source of rules that should govern electrical installations. The current version was published in August 2010 and runs to over 1000 pages.
Whilst the NEC is not law as such, in practice it has been adopted by most states as their set of rules for electrical installations and wiring in buildings (with a few changes here and their depending on the state you are in), and so is now in practice the Electrical Building Code for the United States.
You can read the full 1000 pages plus version online for free here: Building Codes
This is the book that all Journeyman Electricians will consume when undertaking their training, as it is pretty much the standard version across the country.
Though there are some differences between the states, and you can see the individual requirements for your state here: State Regulations
Some of the key NEC rules that need to be followed when installing a new electrical system into a building are:
- 120-volt household outlets MUST be both grounded and polarized.
- New 240 volt units must also be grounded.
- If the building is in a wet location then a GFCI – Ground Fault Circuit Interrupter MUST be fitted to all receptacles (the NEC also defines what it considers a “Wet Location”)
- Wiring needs to be properly insulated to avoid breakages, and the NEC goes into considerable detail on measures to ensure this.
- Areas that have the possibility of gas explosions have to have extra protection to prevent electrical sparks.
- Ratings of circuit breakers need to be accurate and the NEC lays down rules to ensure that the actual amount of current and the maximum amount of current are properly stated.
- Inside a conduit there are a maximum number of conductors that can be used, and these levels are set down by the NEC.
- Temperature ratings can differ depending on the use of the wiring, and they lay down rules for this.
If you are planning on installing electrical wiring then you should refer to the NEC and your local Electrical Building Code for specifics and to the link above for any state specific requirements that you need to know.
