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TECHNICAL SECTION
NEC MADE EASY



THE NATIONAL ELECTRIC CODE
MADE SIMPLE
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
- purpose
Article 725 Remote-Control, Signaling Circuits
CABLE MARKING
TYPE/USES
CL3P
CL2P
CL3R
CL2R
PLTC
CL3
CL2
CL3X
CL2X
Class 3 plenum cable
Class 2 plenum cable
Class 3 riser cable
Class 2 riser cable
Power-limited tray cable
Class 3 cable
Class 2 cable
Class 3 cable, limited use
Class 2 cable, limited use
Article 760 Fire Alarm Systems
CABLE MARKING TYPE/USES
FPLP
FPLR
FPL
Power-limited fire alarm plenum cable
Power-limited fire alarm riser cable
Power-limited fire alarm cable
Article 770 Optical Fiber Cables and Raceways
CABLE MARKING TYPE/USES
OFNP
OFCP
OFNR
OFCR
OFNG
OFCG
OFN
OFC
Nonconductive optical fiber plenum cable
Conductive optical fiber plenum cable
Nonconductive optical fiber riser cable
Conductive optical fiber riser cable
Nonconductive optical fiber general purpose cable
Conductive optical fiber general purpose cable
Nonconductive optical fiber general purpose cable
Conductive optical fiber general purpose cable
Article 800 Communications Circuits
CABLE MARKING TYPE/USES
MPP
CMP
MPR
CMR
MPG
CMG
MP
CM
CMX
CMUC
Multipurpose plenum cable
Communications plenum cable
Multipurpose riser cable
Communication riser cable
Multipurpose general purpose cable
Communications general purpose cable
Multipurpose general purpose cable
Communications general purpose cable
Communications cable, limited use
Undercarpet communications wire and cable
Article 820 Community Antenna Television
CABLE MARKING TYPE/USES
CATVP
CATVR
CATV
CATVX
CATV plenum cable
CATV riser cable
CATV cable
CATV cable, limited use
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
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
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, 760NEC CHART

Type CM - Communications Wires and Cables
Types CL2 and CL3 - Class 2 and Class 3 Remote-COntrol, Signaling, and Power-Limited Cables
Type FPL - Power Limited Fire Alarm Cables
Type MP - Multipurpose Cables
Type PLTC - Power-Limited Tray Cable