Smart Buildings

Fact or Fiction? 5 Ethernet Cable Installation Myths Debunked

Henry Franc
Even installers who’ve worked for decades fall prey to cable installation misconceptions. Do you abide by myth or fact? Find out by reading our blog. 


A blog we penned about cable combing generated lively debate on an industry podcast recently. Did you hear it?


After reading, Chuck Bowser III, RCDD, TECH, reached out and invited me to share more about the topic during his Let’s Talk Cabling podcast. As we talked about the art and science of maintaining an efficient, organized cabling setup, we also addressed common installation myths that even seasoned industry veterans sometimes believe.


This blog offers a glimpse at just a few of the inaccuracies we covered during our dynamic conversation.


Myth 1: You can’t comb Category 6A cables due to alien crosstalk.

Reality: You can comb Category 6A cables (sometimes).


Cable combing allows installers to create neat, organized cables in parallel runs. But because running Category 6A cables and connectors in parallel is a main contributor to alien crosstalk, many installers believe that cable combing shouldn’t be done with Category 6A cables. But this isn’t always true: As long as you install cable from a trusted manufacturer, you can still comb Category 6A cables.


Let’s use Belden as an example. The technology that goes into our cables to minimize alien crosstalk—and the six-around-one testing we complete to ensure proper performance—means our cables can confidently be combed. (Six-around-one testing places the target cable at the center of the bundle, adjacent to the others.)


If a cable manufacturer advises against combing, however, then be sure to listen. They likely know that their cables won’t perform as expected if they’re combed.


Myth 2: Combing cables during installation is a waste of time.

Reality: Combing cables can be a differentiator, not a productivity sink.


Installers are trying to get as much done as they can in a day. Any step that seems like extra work—such as cable combing—may be tossed aside and considered unnecessary. But taking time to comb cables can pay off in many ways. In addition to looking professional and pristine (and preventing performance issues from kinked, tangled or bent cables), it also demonstrates attention to detail.


This is critical in the eyes of customers. Even if they don’t know what cable combing is, they’ll likely feel more confident in the other work you do—termination, testing, etc.—when they see you taking time to neatly organize cables in parallel runs. Good workmanship demonstrates to clients that you value your craft and are good at what you do.


Myth 3: Combing copper cables that also carry power is a fire hazard.

Reality: Combing or bundling is never a fire hazard but can be a performance issue if the right cables are not used.


Using the right cable for the right job is important. Limited-power (LP) cable or Power over Ethernet (PoE) cables won’t catch fire simply due to being combed or bundled.


If they’re installed in an environment that lacks airflow and has a high ambient temperature, however, a problem may arise: The temperature increase may exceed the manufacturer’s recommendations. Cable temperature rise impacts a cable’s electrical characteristics; insertion loss increases as cable temperature rises.


Once the cable temperature reaches a certain level, insertion loss increases rapidly. The “Ethernet” or “data” portion of the cable stops working, and data stops flowing. As soon as data-transmission functionality halts, the cable’s power distribution also goes down. As a result, the cable will never get hot enough to melt or ignite.


Myth 4: As long as they work, installing lower-quality or counterfeit cables isn’t a problem.

Reality: Counterfeit cables can cause safety and performance issues.


Not every manufacturer is a reputable one. Some falsify information or attach fabricated claims to the cables they sell. The industry calls these “counterfeit cables,” which can often be found for sale on marketplaces like eBay, Facebook or Amazon.


For example, to be UL listed, plenum- and riser-rated cables must pass stringent fire safety tests. Counterfeit cables don’t always pass these tests, even though they may display a mark or label indicating compliance. As a result, counterfeit cables may be combustible, contribute to the fast spread of flames and smoke, and ultimately damage property or create loss of life. In many jurisdictions, they also violate building codes.


Performance isn’t optimal, either. For instance, to manage the impact of noise, Category 6A cable conductors should be perpendicular and randomized. But counterfeit cables may not be constructed in this manner, and their performance may reflect that.


Myth 5: Pathway fill and pathway capacity are the same.

Reality: Fill and capacity are different—and it’s important to understand the distinction.


First, it’s critical to note: Without plenty of context, an industry table or calculator can never tell you for sure how many cables will fit into a cable tray or through a conduit. Instead, the answer depends on factors like:

  • Ambient temperature
  • Bends in the pathway or conduit
  • Cable diameter and geometry
  • Coefficient of friction of the cable(s)
  • Humidity
  • Length of the conduit run or pathway
  • Power ampacity of cables in the bundle
  • Pull direction
  • Target fill ratio (40% or 30%, for example?)


You must know these things before you can determine how many cables will fit in the pathway.


It’s also important to understand that “pathway fill” is often inadvertently used to describe “pathway capacity.”


When you’re talking about “fill,” you likely mean “capacity.” Pathway capacity is what truly matters: It refers to a pathway’s ability to accommodate cables, from the minimum number (zero) to the maximum number. (Although today’s installation may not reach capacity, knowing the maximum number is important for future planning.)


Pathway “fill” refers to how truly “full” the pathway is (how much of the tray or conduit is “full”). How much a pathway can hold is different from its capacity and is impacted by multiple factors: application type, future needs, ambient temperatures, etc.


We’re Here to Answer Your Cable Installation Questions

Did you learn something new by reading this blog? We thought you might! You can discover even more insights like these by listening to the entire Let’s Talk Cabling podcast here.


Belden enjoys leading and participating in industry discussions like these. It gives us the opportunity to share anecdotes and insights to help you do your job better.


Have more questions about these topics? Send me a note.


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