The truth about
CATEGORY 5/5e standards
By Donald Sweeney—ITW Linx
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Warning: Many manufacturers will try to
pass on their version of a Category 5/5e protection product when they
are not meeting the proper standards or the application's needs. 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). Often times, this protector will
be advertised as Category 5/5e, but there are three key features that
are needed for a campus environment—primary (UL 497), solid-state,
and certified Category 5/5e. Many manufacturers will provide a Category
5/5e product, but not for the application you are looking for.
Proper Location for Campus Applications (short
or temporary runs where fiber is not needed):
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.
Technology
After looking at the UL listings, the next important aspect to consider
is the technology differences between protectors. Today's telecom
surge protector consist mainly of either gas-tube or solid-state over
voltage devices. When a product is UL Listed for Primary either of
these two devices can be used, but there are differences. Keep in
mind that UL Listings are meant for safety and not to protect the
equipment it's connected to. With that being said, here are the main
differences between the two technologies:
• Gas-Tube: Gas
tube protectors take 4,000 to 5,000 nanoseconds to divert a surge
to ground. This equates to 4,000 to 5,000 feet down the conductive
path. In a LAN application, the channel can only be 100m in length.
So the 5,000 feet would allow the surge to bounce back and forth through
the channel 16 times. Secondly, gas tube protectors can clamp only
as low as 90V. Typical LAN circuits will clamp at 16V, leaving a large
window for surges to damage the equipment involved. Therefore, gas-tube
protectors should never be used for protecting your network equipment.
• Solid-state:
Solid-state protectors take 2 to 5 nanoseconds to divert a surge to
ground. This equates to 2 to 5 feet down the conductive path—essentially
clamping as fast as a surge can travel. These protectors have greater
voltage control and can clamp at low voltages such as in LAN applications.
This protection technology is needed with today's sensitive electronic
equipment and should be used in nearly all applications.
Specifications
The last aspect that needs to be considered is the way in which products
can be marketed in order to pass for you application. Many manufacturers
test their product in-house and do not use third party testing. By
doing this, you are taking their word that it passes for Category
5/5e—and often they don't even meet what they claim. The other
way of going around the standards is using the patch cord standards.
Here are some of the ways in which a vendor can try to get around
the standards you are looking for:
• Category 5/5e:
Many manufacturers will advertise that they meet Category
5/5e, but unfortunately, this is not always true. In order to ensure
the proper performance, ask for third party certification/verification
(e.g. UL, Anixter, Nordex). This is the safest and easiest way to
ensure that you meet the performance you are looking for.
• Protector: The
protector should meet requirements for Category 5e Connecting Hardware
shown in the table below. The main tests include Near End Cross Talk
(NEXT), Return Loss (RL), and Insertion Loss (or Attenuation).
• Patch Cord: If
a protector is classified as a protected patch cord, beware. Patch
cords meet different performance standards shown below. The attenuation
per 100 meters is +20% of the horizontal UTP cable attenuation due
to the stranded conductors. Many manufacturers will classify their
protector under protected patch cords in order to meet the Category
5e performance.
There are many ways to get past the standards for
Cat5/5e and these are only a few examples that have been used by other
manufacturers. When specifying or buying Cat5/5e products, have the
manufacturer or installer verify the performance (as applicable to
your installation) so that you can be assured you are getting a true
Cat5/5e product. ITW Linx offers Cat5e UL Listed primary protection
devices which exceed standards for Cat5e. Call 800-336-5469 for details. |
