ABA Industry, Inc. (a Wonderful Hi-Tech Company)                        639 E. Walnut Street, Carson, CA 90746  (888)534-7776
Plenum cable is cable that is laid in the plenum spaces of buildings. The
plenum is the space that can facilitate air circulation for heating and air conditioning
systems, by providing pathways for either heated/conditioned or return airflows.
Space between the structural ceiling and the dropped ceiling or under a raised floor
is typically considered plenum; however, some drop ceiling designs create a tight
seal that does not allow for airflow and therefore may not be considered a plenum
air-handling space. The plenum space is typically used to house the communication
cables for the building's computer and telephone network; however, it has been
proposed that the growing abandonment of cable in plenum spaces may pose a
serious hazard in the event of a fire as once the fire reaches the plenum space the
airflow present in the space supplies fresh oxygen to the flame and makes it grow
much stronger than it would have otherwise been. Recent testing by the American
Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has
shown that while flame spread is limited by accumulated cable bundles, other
structural concerns may still exist due to increased load on suspended components.
As plenum spaces are restricted from use as areas for storage, the principle behind
removal of abandoned cable is that regulated removal prevents the use of plenum
spaces as a storage area for abandoned cable. Additionally, no high-voltage
powered equipment is allowed in the plenum space because presence of fresh air
can greatly increase danger of rapid flame spreading should the equipment catch on

In the United States, plastics used in the construction of plenum cable are regulated
under the National Fire Protection Association standard NFPA 90A: Standard for the
Installation of Air Conditioning and Ventilating Systems. Plenum cable is jacketed
with a fire retardant plastic jacket of either a low-smoke polyvinyl chloride (PVC)
{patented 1987} or a fluorinated ethylene polymer (FEP). Polyolefin formulations,
specifically based on polyethylene compounding had been developed by at least two
companies in the early to mid-1990s; however, these were never commercialized
and development efforts continue in these as yet untapped product potentials.
Development efforts on a non-halogen plenum compound were announced in 2007
citing new flame retardant synergist packages that may provide an answer for an as
yet under-developed plenum cable market outside the United States. All materials
intended for use on wire and cables to be placed in plenum spaces are designed to
meet rigorous fire safety test standards in accordance with NFPA 262 and outlined in

Note that diligence is required to make sure that a non-plenum airspace stays that
way. A non-plenum airspace can become a plenum airspace by accident if the
ductwork is disconnected and not properly repaired and resealed. Ductwork
disconnection can occur due to building damage such as earthquakes, aging or
adverse environment causing the metal to corrode and fall apart, or simply
negligence on the part of building contractors that leave work unfinished. In all such
cases, discovery and repair of such problems to eliminate unintended plenums is
difficult due to the hidden nature, limited space, and difficult access of most
installed drop ceilings. For highest fire safety it is best to assume all drop-ceiling
airspaces are plenums, whether or not they are officially designated as one.

Cable which is to be run between floors in non-plenum areas is rated as
cable. The fire requirements on riser cable are not as strict. Thus, plenum cable can
always replace riser cable, but riser cable cannot replace plenum cable in plenum
spaces. Twisted-pair, coaxial,HDMI and DVI versions of cable are made in plenum
and riser versions.

In 2006, significant concern developed over the potential toxicity of FEP and related
fluorochemicals including the process aid perfluorooctanoic acid (PFOA) or C8 such
that California has proposed some of these materials as potential human
carcinogens. The NFPA Technical Committee on Air Conditioning, in response to
public comment, has referred the issue of toxicity of cabling materials to the NFPA
Committee on Toxicity for review before 2008.

In 2007, a development program specifically targeting the production of a
non-halogen plenum cable compound was announced to specifically address
lingering toxicity concerns presented by halogenated compounds for use in European
and other global markets.
"Always the Best Alternative"
Plenum vs. Riser
ABA uses a  very
Teflon for its Plenum