Skip to main content

Why Fire Alarm Plenum and Riser Ratings Are So Important

 Fire alarm cable is of the utmost importance to public safety, as it allows the different nodes within a fire alarm system to communicate. If there’s a problem with the wiring and the system can’t communicate, it can’t relay important information about heat, smoke detection, or carbon monoxide to other nodes, smoke detectors, or alarms in the system.

Talk to any civil or electrical engineer about that and they’ll concur. That’s why all of the minute details associated with wiring should be understood - thoroughly understood - before attempting to complete plans or install wiring.

With that in mind, let’s take a closer look at two important fire alarm cable ratings - for riser-rated and plenum-rated cables.

What Is Riser Space?
Riser space, as the name might suggest, allows for utilities to “rise” through a building. That is, it is the vertical space reserved for things like communication lines, water pipes, conduits, and of course, alarm cables, to be vertically distributed throughout a building.

Think of riser space as the “space between the walls” because, in most instances, that’s exactly what it is. It’s also typically sealed off to access from the inside.

As a result, riser-rated cables are typically built to lower or less stringent specifications than plenum-rated cables, but this is not always the case (see below).

What Is Plenum Space?
Plenum space, unlike riser space, is space that is hollowed out between the floor and the ground, or more commonly, between a drop ceiling and the actual ceiling. While plenum space can also be used for water pipes and conduits, it is also the space in a building that is reserved for ductwork and HVAC.

As a result, it is possible for the contents of the plenum space to communicate with the rest of the building. That is to say, if there were, for instance, smoke in the plenum space, it could get into the living quarters of the associated floor.

Consequently, plenum-rated fire alarm cables (and other cables) must be much more resilient to heat and fire than riser-rated cable.

How Does This Affect Fire Alarm Cable?
Since fire alarm cable must be safe for use around people and also resilient to fire in order to work, this has some implications for alarm cable specifications.

Generally speaking, all fire alarm cables should be high heat resistant, self extinguish, and not produce toxic smoke when burned. However, pllenum-rated cable must be more resistant to heat and fire than riser-rated cable because of the nature of plenum space. As a rule, you can use plenum-rated cable in riser space but not a riser-rated cable in plenum space.

Also, one thing to keep in mind is that there are also riser and plenum-rated conduits. If you use a plenum-rated conduit, it may be possible for you to use riser rated cable - but check with an electrical engineer to be sure.

Looking for Fire Alarm Cable?
Looking for a non-power limited or power-limited fire alarm cable that stands up to specific requirements? Visit EWCS Wire at EWCSWire.com or get in touch with them to learn more about their high-quality alarm cables and other products.

Comments

Post a Comment

Popular posts from this blog

Wire Voltage Ratings, Explained

Voltage rating is one of the most basic, fundamental ratings associated with electrical wire and cable, given in volts. Voltage itself is a measurement of electrical potential, calculated by multiplying a given electrical current (in amperes, I), by the resistance of a conductor, (in ohms, Ω). The material of the conductor, as well as the thickness, will all impact resistance. These things, being variables from which voltage is drawn, affect voltage rating. Think of voltage as the force “pushing” the electricity through a wire or cable, similar to how plumbing pipes experience line pressure, except that line pressure is measured in PSI instead of volts. Just like with water pipes, it is essential never to exceed the voltage rating of a given conductor - but instead of a burst pipe, exceeding the voltage rating of an electrical conductor can cause overheating, fires, and an elevated risk of dangerous electrical shock. But what exactly is a wire’s voltage rating? ...
Post a Comment
Read more

Common Questions About Security and Alarm Cables, Answered

Not sure which type of security or alarm cable your facility or system needs? Hopefully, these answers to common questions can help! What cable is used for alarm systems? Security and alarm systems are usually wired with small-gauge wire specifically designed for the purpose. For instance, many security systems are wired with 12 and 18 AWG gauge alarm wire, as these low-voltage applications do not necessarily require larger, heavier wires. However, larger or wire gauges may be required depending on the circumstances. Also, there are some unique requirements for some systems. For instance, fire alarm cables must be made with specific insulation that is heat resistant and which does not produce toxic smoke when burned. What gauge cable do you need for alarm systems? Only your specific system requirements can answer that question, but often large wire gauges (that is, smaller wires) are used as security and alarm cables because of the low-voltage, low-current application. What is ...
Post a Comment
Read more

Choosing The Right Marine Electrical Wire

When it comes to wiring in a marine environment, there are a lot of rules to consider. Even accomplished home electricians might have some difficulty safely wiring a boat for the first time. Not only do you need to use marine electrical wire , but you also need to follow the guidelines from the American Boat and Yacht Council(ABYC). One of the most important steps is choosing the right wire, which differs significantly from the wires used in homes. Anyone who has wired up a home is familiar with romex cable. These cables feature solid copper conductors that are insulated in rubber, wrapped in paper, and then jacketedin a final PVC Jacket. These cables are great at transferring electricity, but they are not built for boats. Boats are constantly moving environments, and stiff cables would quickly crack and pull themselves loose from their connections. In order to be as flexible as possible, marine electrical wires and cables have to use finely stranded copper conductors. Ev...
Post a Comment
Read more