Plenum cables are run in that space (the plenum) to minimize the hazard from burning cables in a fire. Non-plenum, often called riser cables are less expensive and are used in spaces that do not intermingle with normal air circulation: attics, closed walls, conduit, etc..
In this manner, why would you use plenum cable?
Plenum rated cable has a special insulation that has smoke and low flame characteristics. At that point, the use of plenum cables ensures safety. However, use of plenum spaces may pose a serious hazard in case of fire. Once fire reaches the plenum space, few barriers exist to contain smoke and flames.
Secondly, should I use plenum cable in my house? If there is no sheet metal duct; just the open ceiling or wall space, then you are required by law to use Plenum Rated cable. The lack of wall or ceiling return air grates is usually a sure sign that you require Plenum Rated Cable. Computer Rooms typically use a raised flooring system for the server racks.
Secondly, what is the difference between plenum and riser cable?
Many customers ask, “What is the difference between plenum rated cable & riser rated cables.” Plenum rated cables are used in plenum areas meant for use in commercial and residential spaces. Riser rated cables run between floors through cable risers or in elevator shafts in non-plenum areas.
Is plenum cable required in conduit?
When no conduit is used, plenum cable is often required since the cable is considered to be freely installed. Plenum spaces allow fire and smoke to travel quickly. This special jacketing makes the cable smoke less than regular PVC cable and the smoke that is emitted is less toxic.
Related Question Answers
What is plenum and what must you do to be able to run cable through plenum space?
When you run cable through any building you first need to consider plenum spaces. Plenum spaces are the open spaces above the ceiling or below the floor that are used for air circulation. Any cable that you run through plenum spaces must be plenum rated, even wiring used for information transfer, like Cat5 wiring.What is considered a plenum space?
A plenum space is a part of a building that can facilitate air circulation for heating and air conditioning systems, by providing pathways for either heated/conditioned or return airflows, usually at greater than atmospheric pressure.Is an open ceiling considered a plenum?
An open ceiling in a retail store would not be a plenum area. If this was the case all the merchandise would need to be rated to be installed in environmental air ducts.Is plenum cable fire retardant?
Plenum cable is fire-resistant (it will melt, but not support combustion or carry a flame). It also emits less toxic fumes when it does burn. If you look at some network cable, you can see which type it is: CMP: Plenum rated cable (plenum means "air handling space")What is HVAC plenum?
Supply Plenum A plenum is an air-distribution box attached directly to the supply outlet of the HVAC equipment that heats or cools the air to make the house comfortable. The ductwork that distributes the heated or cooled air to individual rooms of the house connects to the plenum.Is an attic considered a plenum?
According to every dictionary I looked at, the area below the roof of a home and above the ceiling joists is considered an attic, regardless if it is conditioned or not. In this case it would be a conditioned attic. Wiring within a plenum does not have to be in conduit.Can coaxial cable start a fire?
Can a cut cable wire cause a fire? If by 'cable wire' you mean Coax cable for the TV, or Internet, then the answer is no. The power/voltages in the cable are way to low to produce a spark which is usually what triggers flame.Do I need plenum cable?
Plenum cable can be safely installed just about anywhere, although it might be considered overkill in spaces where open air and the potential for heat and flame are not necessary considerations. There are some instances in which you absolutely must install plenum cable, however.What is plenum made of?
Plenum cable is coated with a fire-retardant coating (usually Teflon) so that in case of a fire it does not give off toxic gasses and smoke as it burns. Twisted-pair and coaxial versions of cable are made in plenum versions.Is plenum cable waterproof?
It may be that when you read the title of this blog, "Waterblocking" that you thought to yourself, "Isn't ALL jacketed wire and cable waterproof?" The answer is "No." Almost every jacket compound, from PVC to Polyethylene to Teflon® is at least water resistant, so they can get wet and then dry out and they cables wouldShould we use plenum or riser rated cables?
Plenum rated cables have a higher fire rating for both commercial and residential use. When cables are needed in the air ducts, plenum cables are the primary choice. Riser cables, namely CMR cables, are widely used for regular networking from floor to floor in non-plenum areas.Can riser cable be used in plenum?
Cable which is to be run between floors in non-plenum areas is rated as RISER cable. 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.What is a plenum ceiling?
In building construction, a plenum (pronounced PLEH-nuhm, from Latin meaning full) is a separate space provided for air circulation for heating, ventilation, and air-conditioning (sometimes referred to as HVAC) and typically provided in the space between the structural ceiling and a drop-down ceiling.What is a non plenum ceiling?
Laqfoil stretched ceilings always create a non-plenum airspace, an area filled with air that doesn't move, because the profiles which support the membrane around the edges always take up some space between the wall or ceiling and the membrane, typically just under one inch, more if desired for design reasons.Is plenum cable outdoor rated?
Plenum cable is rated for the “plenum spaces” in buildings, which are simply the parts of the building that facilitate air circulation in heating and air conditioning systems. This designation simply means that the cable has been engineered to be buried without any kind of outside protection.What is riser plenum cable?
A Riser cable (CMR) / backbone cable is a cable that is run between floors in non-plenum areas. A plenum cable can always replace riser cable, but riser cable cannot replace plenum cable in plenum spaces.Is EMT plenum rated?
Emt installed in the plenum with non plenum rated conductors inside would be a seperate issue. It's allowed to install thhn conductors in emt is said space and they are not plenum rated.What is CMR rated cable?
CMR cable, often called “riser-rated cable,” is constructed to prevent fires from spreading floor to floor in vertical installations. It can be used when cables need to be run between floors through risers or vertical shafts. Even higher rated is CMP (plenum-rated cable).How do I know if I have a plenum ceiling?
If the space above the drop ceiling is used for environmental air transfer, meaning the air above the drop is apart of the air return, then it is a plenum area and plenum rated cables shall be installed. 
