Handbook for Sound Engineers

Transmission Techniques: Wire and Cable 441

14.28.5 Plenum Cable

Plenum cable is used in ceilings where the air handling

system uses the plenum as the delivery or the return air

duct. Because of its flame-resistant and low

smoke-emission properties, the special compound used

in plenum cable jackets and insulations has been

accepted under the provisions of the NEC and classified

by Underwriters Laboratories Inc. (UL) for use without

conduit in air plenums.

In a typical modern commercial building, cables are

installed in the enclosed space between drop ceilings

and the floors from which they are suspended. This area

is also frequently used as a return air plenum for a

building’s heating and cooling system. Because these

air ducts often run across an entire story unobstructed,

Figure 14-23. National Electrical Code substitution and hierarchy. Courtesy Belden.

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Plenum

Riser

General

Purpose

Dwellings

CATVP

CATVR

CATV

CATVX CMX

MPG

MP

CMG

CM

MPR

CMR

MPP

CMP CL3P

CL2P

PLTC

CL2R

CL3

CL2

CL3X

CL2X

CL3R

FPL

FPLR

FPLP

MPP, MPR, MPG, MP—Multipurpose Cables

CMP, CMR, CMG, CM, CMX—Communications Cables

CL3P, CL3R, CL3, CL3X, CL2P, CL2R, CL2, CL2X—Class 2 and Class 3 Remote-Control, Signaling and Power Limited Cables

FPLP, FPLR, FPL—Power Limited Fire Alarm Cables

CATVP, CATVR, CATV, CATVX—Community Antenna Television and Radio Distribution Cables

OFNP, OFNR, OFNG, OFN—Nonconductive Optical Fiber Cables

OFCP, OFCR, OFCG, OFC—Conductive Optical Fiber Cables

PLTC—Power Limited Tray Cables

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OFNP OFCP

OFNR OFCR

OFNG OFCC

Non-

conductive Conductive

Figure 14-24. Canadian Electrical Code cable substitution
hierarchy per C22.2 #214—Communication Cables.

CMP

FT6

CMR

UL1666 — Riser

CMG

FT4

CM

UL Vertical Tray

CMX

UL VW1

CMH

CSA FT1

The following cable substitutions

may be used:

Communication cables marked

MPP, CMP, MPR, CMR, MPG,

CMG, MP, CM, CMX, CMH, FT6,

and FT4 have been found to meet

the standard criteria for FT1.

Communication cables marked

MPP, CMP, MPR, CMR, MPG,

CMG, and FT6 have been found to

meet the standard criteria for FT4.

Communication cables marked MPP

and CMP have been found to meet

the standard criteria for FT6.