Plenum vs Riser Cables: Which Is Right for Your Building? Plenum and Riser are two integral components of building infrastructure. A plenum is a space between the ceiling of a building and the floor of the next level. It is usually used for air circulation and/or wiring and pipes.
A riser, on the other hand, is a vertical pipe or conduit that runs between floors of a building and is used to carry services such as water, gas, and electricity.
Although they both serve similar purposes in building infrastructure, there are some distinct differences between plenum and riser that should be considered. Let’s dive into the article.
Differences Between Plenum and Riser Cables (With Table)
| Terms | Plenum | Riser |
| Description | Plenum is a pressurized air space used for air distribution. | Riser is a vertical cable pathway. |
| Use | Plenums are used to circulate air throughout a building. | Risers are used to organize and distribute cables and wires between floors of a building. |
| Material | Plenums are usually made of sheet metal or other non–combustible material. | Risers are typically constructed of metal or plastic. |
| Fire rating | Plenum cables are specially designed to resist fire and have a higher fire rating. | Riser cables have a lower fire rating and are not designed to resist fire. |
| Installation | Plenums are installed between the finished ceiling and the structural ceiling. | Risers are installed vertically between floors. |
| Maximum temperature rating | Plenums are designed to withstand temperatures up to 300°F. | Risers are designed to withstand temperatures up to 150°F. |
| Fireproofing | Plenums must be fireproofed to protect the cables and wires within. | Risers are not required to be fireproofed. |
| Code Compliance | Plenums must comply with local building codes. | Risers must comply with local building codes. |
| Purpose | Plenums are used for air distribution. | Risers are used to organize and distribute cables and wires. |
What Is a Plenum?
A plenum is an enclosed space within a building‘s structure that is used for air circulation. It is typically located directly above a dropped ceiling or below a raised floor.
It is connected to the building‘s heating, ventilation, and air conditioning (HVAC) system. The plenum is designed to distribute conditioned air from the HVAC system throughout the building and to return dirty air back to the system.
The space is usually pressurized to ensure that the air flows freely through the ducts and grilles. Plenums are also sometimes used as pathways for electrical wiring, telecommunications cables, and fire suppression systems.
What Is a Riser?
A riser is the vertical cabling system used to connect telecommunication rooms and other equipment located on different floors of a building. It is often used to connect the main distribution frames (MDFs) of various floors in a building.
It typically consists of Category 1, 2, 3, 5, and 6 cables, which are used to connect computers, modems, and other equipment to a telephone line or other network cable.
Riser Cabling systems are typically installed in commercial buildings, industrial facilities, and other large structures, and they can be used to support a variety of telecommunication and data communications applications.
The Cost Difference between Riser and Plenum Cables
The cost of plenum cables is typically higher than the cost of riser cables. Plenum cables are more expensive because they are fire–resistant and have additional shielding, which increases their cost. Plenum cables generally cost around $1.00 – $2.00 per foot, while riser cables cost around $0.25 – $0.75 per foot.
Features of Plenum Cable
Plenum cable is a type of cable used for data or telecommunications in commercial or residential buildings. It is designed to provide a safe and reliable solution for transmitting power and data signals.
1. Fire Resistance
Plenum cables have a fire retardant jacket that is designed to reduce the spread of fire in the event of a fire. This is important in buildings as it helps to reduce smoke and flame in the event of a fire.
2. Low Smoke Emission
Plenum cables have a low smoke emission which is important in the event of a fire. This helps to reduce the amount of smoke that is released into the air, making it safer for people in the building.
3. Reduced Electromagnetic Interference
Plenum cables are designed to reduce the amount of electromagnetic interference caused by the data or power signals being transmitted. This is important in a building where multiple devices and cables are present, as it can help to reduce the amount of interference.
4. Installation
Plenum cables are designed to be easy to install in a building, as they are lightweight and flexible. This makes them ideal for use in buildings where space is at a premium.
5. Durability
Plenum cables are designed to be durable and last a long time, even in harsh conditions. This makes them ideal for use in buildings where they will be exposed to high temperatures and humid conditions.
6. Low Toxicity
Plenum cable is designed to be non–toxic and non–carcinogenic, making it safe for use in public spaces.
7. Flexibility
Plenum cable is designed to be flexible, allowing it to be installed in tight spaces and around corners.
8. Low Electrical Resistance
Plenum cable is designed to have low electrical resistance, meaning it is able to transmit signals more efficiently.
Related: 10 Differences Between Bus Duct And Cable Tray (With Table).
Features of Riser Cable
Riser cable is a type of network cabling used to connect different floors in a building or vertical space. It is used for voice, data, and video applications, and is commonly used in commercial and institutional buildings. The main features of riser cabling include:
1. Flexibility
Riser cable is highly flexible, allowing it to be used in spaces with multiple floors or vertical levels. It can also be used to connect different types of devices, such as computers, phones, and other electronic devices.
2. Durability
Riser cable is designed to be durable, and resistant to environmental hazards such as extreme temperatures, dust, and moisture. This ensures that the cable will remain functional for many years.
3. Cost-Effectiveness
Riser cable is cost–effective, as it can be used in spaces where traditional cabling is too expensive. This is especially true for buildings with multiple floors, as riser cabling can be used to connect different levels.
4. Installation
The riser cable is easy to install and maintain. It does not require complex wiring, and the cables can be quickly and easily connected.
5. Security
The riser cable is secure, as it is designed to be resistant to unauthorized access. This helps to ensure that data and other sensitive information remain protected.
6. Compatibility
Riser cable is compatible with a variety of other cabling systems, including fiber optic cabling, Cat5, and Cat6 cabling, and coaxial cabling. This makes it a great choice for businesses and organizations that have different cabling needs.
Plenum vs Riser Cables: Which To Use?
It really depends on the needs of the specific project. Risers are usually used for vertical runs and plenums for horizontal runs, but this is not a hard and fast rule. Risers offer more predictable performance, better control of air movement, and lower installation costs than plenums.
On the other hand, plenums provide more flexibility when it comes to design, better air distribution, and faster installation. Ultimately, the best option depends on the specific application and the individual needs of the project.
In my opinion, plenum cables are the better choice for most applications. They are more fire–resistant, have better insulation, and can reduce interference. However, if you are installing in an area where the fire is not a major concern, then riser cables may be a more cost-effective option.
Terms to Know when Choosing Plenum Vs Riser Cabling
Already you know the differences between plenum and riser. Knowing the following terms before buying a cable can help you to simplify the process of identifying the correct type of cable and also ensure that the correct cable is used for the job at hand.
Additionally, it can help you to reduce the amount of time spent trying to sort out the appropriate cable, as well as reduce the amount of confusion that can arise when dealing with different types of cables.
PLENUM CABLE
- CMP: (Communications Multipurpose Cable) – A type of plenum cable used for communications and networking applications.
- CL3P: (Communications Level 3 Plenum) – A type of plenum cable used for high-speed applications such as audio, video, and data.
- PVC: (Polyvinyl Chloride) – A type of plastic used in plenum cables for insulation.
- FTP: (Foil-Twisted Pair) – A type of plenum cable where each pair of wires are wrapped in foil to reduce electromagnetic interference.
- UTP: (Unshielded Twisted Pair) – A type of plenum cable where each pair of wires are twisted together to reduce interference.
RISER CABLE
- CMR (Communications Riser): A type of riser cable used for communications and networking applications.
- CL2R (Communications Level 2 Riser): A type of riser cable used for high-speed applications such as audio, video, and data.
- CMP: (Riser-rated Communications Plenum Cable) – A type of riser cable that is fire retardant and suitable for in–ceiling applications.
- FTP: (Foil-Twisted Pair) – A type of riser cable where each pair of wires are wrapped in foil to reduce electromagnetic interference.
Plenum Cables for Smart Buildings
Plenum cables are the ideal choice for smart building applications. These cables are designed to be installed in plenum spaces, or the areas above suspended ceilings and below raised floors.
- This type of cable is built with a flame–retardant jacket that helps to minimize the spread of fire, which is an important safety feature for any smart building.
- Plenum cables also offer superior performance, with lower insertion loss and better signal integrity than other types of cables.
- In addition, these cables are designed to be more resistant to environmental factors such as temperature, humidity, and moisture.
With their reliable performance and flame–retardant properties, plenum cables are the perfect choice for smart building applications.
Conclusion
In conclusion, the plenum and riser are two integral components of building infrastructure that have distinct differences that are already discussed above. I hope by reading the differences between Plenum and Riser cable, now you will be able to identify the best one. Yet have a question? See the FAQ section and drop your question in the comment section. I will give the answer to your query.
Frequently Asked Questions
Can Riser be Used In Place of Plenum?
No, I do not recommend using a riser in place of a plenum. A plenum is designed to provide airflow control, whereas a riser is designed primarily to provide support for an HVAC system. Additionally, most risers are not designed to handle the pressures and temperatures associated with HVAC systems, and so could fail if used in place of a plenum.
Can I install a plenum-rated cable in a riser shaft?
It depends on the specific cable and the requirements of your local building codes. In general, plenum-rated cables are designed for use in air-handling spaces, such as plenum areas, risers, and ducts.
However, not all risers are considered plenum spaces, so you will need to check with your local building code to determine whether it is appropriate to use a plenum-rated cable in your specific situation.
How do you identify plenum cable?
Plenum cable is identified by its jacket material, which is typically made of a fire–retardant material such as Teflon (FEP), PVC, or a halogen–free material such as low–smoke polyvinyl chloride (LSZH).
Plenum cable will also typically have a UV–resistant outer jacket and may be printed with the words “plenum“ or “CMP“ for communications multipurpose plenum.
How do I know if my ceiling is plenum rated?
To determine if your ceiling is plenum rated, you will need to check with your local building code or consult with a professional in the construction or electrical industry.
In general, a plenum space is an air-handling space within a building, such as an area above a suspended ceiling or below a raised floor. These spaces are typically required to have certain fire-resistant and air-flow characteristics in order to prevent the spread of fire and promote proper air circulation. If your ceiling meets these requirements, it may be considered plenum rated.
However, it is always best to check with a professional or refer to your local building codes to be sure.
Do You Need Plenum-Rated Cable if it’s in Conduit?
In my opinion, it is not necessary to use a plenum-rated cable if it is in a conduit. Plenum-rated cables are typically used in areas where there is a large quantity of air circulation, such as in drop ceilings or raised floors, in order to minimize the spread of fire and smoke.
Since conduit offers a degree of protection from air circulation, the plenum-rated cable is not necessary for this situation. However, it is important to check local code requirements for specific applications, as there may be specific requirements for particular installations.