To aid in the prevention of fires as well as electric hazards there exists a published set of guidelines commonly referred to as the National Electric Code. This code is designed to ensure the safe installation of wiring and equipment in commercial and residential locations.
In 1987 the NEC introduced listing requirements governing communication and power limited circuit cable. These requirements defined the acceptable fire resistance levels, initiation of fire and flammability characteristics.
It is essential to be knowledgeable of these standards when specifying or installing any cable.
Although there exists multiple codes, we will list and attempt to simplify this vast complexity of listings.
Using the NEC
There are five main articles that refer to communication and power limited cables.
Within each article you will find:
- installation application and environment
- cable construction
- required markings
Within each article you will find that there are certain permissible substitutions. Ordinarily this applies to using cables further along in the hiarchy of listings, for a lower listed application. Please refer to our NEC substitution charts to determine allowed substitutions
Installation Environment (click here)
In addition to cable circuit type, consideration must be given to the installation environment. The NEC defines four major categories for such.
Plenum- This is defined as an area such as ducts, plenums or any space used for environmental air without conduit. Cable must have adequate fire resistant and low smoke producing characteristics. The highest environmental listing available, this is an acceptable substitution for the other three listings.
Riser- This is a listing designed for a vertical run as in from floor to floor. Cable must have fire resistant characteristics and be capable of preventing the spread of fire between floors.This listing is acceptable for the other two listings.
General Purpose- This listing encompasses general purpose installations other than risers, ducts, plenums or other air handling space. Cable must be resistant to the spread of fire. This listing is acceptable for the one remaining listing.
Restricted Applications- This flame resistant cable is for limited use in dwellings and in raceways. Cable must be installed in non-concealed spaces under 10’, fully enclosed in conduit of raceway, or have a diameter less than .25” for a residential dwelling. This listing is the lowest available and is not an acceptable substitute for any other.
Article 800 Communications Circuits (click here)
1999 National Electrical Code Substitution Chart
The following chart explains the NEC cable hierarchy and will give you a “picture”
view of how this all fits together. The chart starts with the higher listed cables at the top descending to the lower listed cables. Following the arrows will allow you to find what listing can be substituted for others.
NEC Substitution and Hierarchy Article 800, 725, 760