The Ultimate Guide to Plenum Rated, Riser Rated, and LZSH Cables: Know the Difference

Selecting the right type of cable for your building or network installation can be a confusing task. It can be especially challenging when it comes to understanding the differences between plenum cables, riser-rated cables, and LZSH cables.

These cables are classified based on their fire-safety ratings, and each is designed for specific environments. In this guide, we’ll clarify the distinctions between these cable types, explaining where each is used, why it matters, and how to choose the best one for your needs.

What are Plenum-Rated cables?

Plenum-rated cables are designed to be used in spaces where air circulates, such as the air handling spaces in the ceiling. These spaces are known as plenums and are often used for heating, ventilation, and air conditioning (HVAC) systems.

Because these areas have air that circulates throughout the building, using the wrong type of cable can lead to serious fire hazards. The plenum rating definition refers to cables that are made with fire-resistant materials, allowing them to meet strict fire safety standards.

These cables are usually jacketed with a low-smoke, fire-retardant material that reduces the risk of a fire spreading through the building. The plenum rating meaning indicates that the cable can be safely installed in the plenum space, making it a preferred choice for many commercial buildings.

What are Riser Rated Cables?

Riser-rated cables are typically used in vertical spaces, like the riser shaft of a building. These areas are used to run cables between floors in a building. The key feature of riser-rated cables is that they are designed to resist the spread of flames in a vertical manner.

These cables are not as fire-resistant as plenum cables but are still rated to prevent fire from climbing up the cables between floors. Riser-rated cables are often used for network connections between different floors of a building or within the walls of the building.

The riser cable vs. plenum cable debate often comes up when deciding which cable to use in a particular application. Keep in mind that the riser rating is not as stringent as the plenum rating, but it is still an important consideration.

Riser-rated cables are typically jacketed with a flame-retardant material, which makes them safe for use in vertical riser shafts. However, these cables should not be used in plenums, where air circulation could increase the risk of fire.

What are LZSH Cables?

LZSH (Low Smoke Zero Halogen) cables are designed to release minimal smoke and no halogen gases in the event of a fire. This makes them a popular choice in environments where safety is a top priority, such as airports, hospitals, and high-rise buildings.

LZSH cables are typically used in areas where the potential for smoke inhalation is a concern. These cables are not fire-rated like plenum or riser cables but are often used in conjunction with other safety-rated cables to provide a safer environment in the event of a fire.

Thus, they are commonly used in communication riser setups, where low smoke emissions are critical in ensuring the safety of the building’s occupants.

When to Choose Plenum-Rated Cables?

In some cases, you might be tempted to use plenum-rated cabling even outside of plenum spaces because of their superior fire resistance. However, this can be costly, as plenum-rated cables tend to be more expensive than riser-rated cables. Here’s when you should choose plenum cables:

• If the cable will be installed in the plenum space.
• In case fire safety and reducing smoke in the event of a fire is a top priority.
• If the building’s code requires plenum-rated cables for specific areas.

When Choose Riser-Rated Cables?

Riser-rated cables should be used when you are wiring between floors in a building. They are also generally less expensive than plenum cables, so if your application doesn’t require the extra fire safety features of plenum-rated cables, riser-rated cables might be a better fit. Here are some reasons to choose riser cables:

• If the cable is intended for use in a riser shaft (vertical spaces between floors).
• If you are working in an area where fire safety codes do not mandate the use of plenum cables.
• If cost is a concern you still need to meet minimum fire-resistance standards.

When to Choose LZSH Cables?

LZSH (Low Smoke Zero Halogen) cables are an important choice when fire safety and low environmental impact are vital. While not rated for plenum or riser spaces, LZSH cables are designed to produce minimal smoke and no halogen gases when exposed to fire. Here’s why you might opt for LZSH cables in your installations:

• If you need cables for areas where smoke could hinder evacuation (hospitals, airports, stadiums)
• If your building has strict environmental or safety regulations requiring low-smoke, halogen-free cables
• If you’re wiring critical systems like emergency alarms, fire detection, or data centers, use LZSH cables

Conclusion

Understanding the differences between plenum-rated cables, riser-rated cables, and LZSH cables is essential for making the right choice for your building’s wiring needs.

By considering factors like installation location, fire safety, and cost, you can ensure the safety and efficiency of your electrical and data systems. For your next project, trust ATS Cables to provide you with top-quality, compliant cables for any application.

Frequently Asked Questions (FAQs)

What is the main difference between plenum and riser cables?

Plenum cables are fire-rated for use in air-handling spaces, while riser cables are designed to prevent the spread of flames in vertical spaces between floors.

Can I use a riser-rated cable in a plenum space?

No, riser-rated cables are not suitable for plenum spaces due to the higher fire safety standards required for those areas.

What is the type of insulation commonly used on plenum-rated cable?

Plenum cables typically use low-smoke, fire-retardant insulation materials, such as Teflon.

Are LZSH cables the same as plenum cables?

No, LZSH cables are designed to produce less smoke and no halogen gases during a fire, but they are not specifically rated for plenum or riser spaces.

Is plenum cable better than riser cable?

Plenum cables offer superior fire safety and are recommended for air-handling spaces, but riser cables are sufficient for vertical spaces and less expensive.