Ethernet Cable Section – Consider the UL Listing – NEC Requirements

UL LISTINGS The greatest misconception is most likely the UL standard for different applications. People believe that just because something has a UL mark on it, it must be safe to use the product. Different UL Listings mean different things for good reasons – safety. The highest UL Listing for surge protection products is UL 497. This can easily be confused with UL 497A and UL 497B. Although the Listings look similar, the testing procedures for each are extremely different. Here is a quick look at the differences:

— UL 497 – Primary Protection: The Primary Protector is used at Building Entrances and is capable of withstanding the highest level of over-voltage surges- lightning. These devices are required by NEC Article 800 to protect buildings and humans.

— UL 497A – Secondary Protection: The Secondary Protector is located between the building entrance / Primary protector and the equipment intended to be protected. These protectors are intended to protect buildings, humans and sensitive electronic equipment. The TIA/EIA 568 standard does not allow fuses and PTC’s to enable secondary protection due to the 100 ohm impedance mismatching.

 — UL 497B – Isolated Loop Protection: Isolated Loop Protectors are designed to handle over-voltage events which are introduced within a building. The protected “loop” must not be exposed to the outside world. These protectors are not designed to protect against lightning type surges but are for low voltage protection instead

 

In a campus environment, the NEC requires that you protect any conductive path entering or leaving a building (Article 800). This protector must be agency listed (i.e. UL 497).

 

There are Different Standards for Patch and Other Cables

Patch Cords have lower standards of protection. Some manufacturers use small print references to patch cords to hide the fact that their cable doenst meet the requirements.

 

There is no  licensing organization / enforcement of standards  

There are two versions of the specification--one from TIA and one from ISO--but there is no enforcement organization or licensing involved.   There's nothing to prevent somebody from labeling cable with any "category" he wants to label it with, and people do; we see cable that badly fails 5e labeled as 6.   Therefore it is best to purchase certified cable.


“Rated Up To” vs. “Certified to”

Although most cable resellers claim 350MHz or higher ratings on their boxes and marketing literature, the cable standards only offer a passing grade based on the 100MHz requirements in the Category 5E published standard.  
Why? The higher numbers are more of a marketing description than a factual description.  
To make this simple to understand, think of water passing through a straw. Although you can push one million gallons of water through it, would you still choose a straw? Using that comparison, we could say that the straw is tested to one million gallons of water flow.  
Basically, the 500MHz ratings you read do not tell you much about the ability of the cable to pass a 100Base-TX or a 1000Base-T signal. There are many factors involved that are more important than a marketing number listed on a cable.  
The important thing to remember is that Category 5E cables are certified for 100MHz and Category 6 cables are certified for 250MHz.

 

Category 5E cables do carry Gigabit Ethernet  

Category 5E cable is the minimum requirement for gigabit transmission. However, Category 6 is recommended for new installations where Gigabit Ethernet is planned.
Why? When the standard for gigabit was developed, one of the requirements was that it would work over existing cables. The augmented Category 5 standards or Category 5E was developed to define this requirement.  
Before choosing a cable, decide what type of network speeds will be used. If this is a new installation and you plan to have gigabit connections, install Category 6 cable. If this is an update to an existing system and some of the links are already Category 5E, then use the same cable rating as the installed links.

 

Connectors Count – Do not build your own CAT6

The Category 6 connectors are harder to assemble and sometimes require special tools.  . If you use a Category 6 bulk cable then make sure you have Category 6 connectors. Not all connectors are built the same.  
Also, it is not just simply a matter of sticking the wires into a plug and crimping. Much of what makes a hi-performance plug is in the assembly process

 

Cat 5, 5e, 6 and Distance

The standard and therefore certifications are for 100m. This applies to 5, 5e and 6.



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