Brief introduction of Armored vs. Non-Armored Fiber Optic Cable

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 Fiber
optic cable is offered with two different types of armor – aluminum interlocking
armor for indoor cables and corrugated steel tape for outdoor cables. The
armoring offers an added layer of mechanical protection to the cable. The
differences between the two types of armor are the material that the armor is
made of and the way it is applied to the cable. Aluminum interlocking armor is
made of – you guessed it – aluminum – and it is wrapped helically around the
fiber cable. This type of armor is used in indoor rated cables. The second kind
of armor is corrugated steel tape. This armor is composed of coated, corrugated
steel and it is folded

 

longitudinally
around the cable. Corrugated steel tape is found in outdoor rated cables. Fiber
optic cables are offered in many different cable constructions, each with their
own advantages and disadvantages. Armored cables have some benefits when you
are installing them, and there are applications where it will be more cost
effective to use this kind of cable. Some of these cables are more versatile
than others, and if you have some on hand, it may help you to be ready for any
situation (like an unexpected network outage). Other times the decision will
come down to the engineer and the type of cable they prefer for the job. There
are costs associated that can help you make the decision about the style you
choose. Armored cable costs more than non-armored, but the labor to install it
may be a less expensive, and this could make it more feasible to install
armored cable. Below we will discuss a few different cable constructions and
where you can pick between the two, armored versus non armored.

 

Distribution
Cable

 

Distribution
Cable is a tight buffered cable construction; inside of the outer jacket is a
layer of aramid yarn and multiple fibers with 900um tight buffer jackets.
Distribution cables are multi
fiber cables that are used for indoor applications. The color of the
outer jacket for single mode is typically yellow and for multimode the outer
jacket can be orange, aqua, magenta or lime green depending on the multimode
fiber type. Having a 900um jacket on the fibers allows you to be able to
terminate a connector without having to do a build up on the fiber. Where this
cable is being run indoors will help to determine if armor is needed. When
fiber optic cable is being run in harsh environments or high traffic areas, it
would be good to have the extra protection of the armored cable. This may be in
a warehouse environment or it may be above a ceiling that is accessed
regularly. Indoor armored cable uses an aluminum interlocking armor that helps
to protect the fiber cable, along with increasing the durability of the fiber
run. Sometimes you may be required to run cable in conduit indoors. The
aluminum interlocking armored cable can help eliminate the need for conduit and
it can be substituted for running conduit. Installing conduit can increase the
cost of the installation because you have to spend time to place the conduit. Then
you have to pull the cable through the conduit which means you have essentially
doubled the labor costs to perform the installation. When using the aluminum
interlocking armor cable, you now just have to pull your cable once. When
running the armored cable in a cable tray or under a floor or through a ladder
rack – any location where it will be installed and is not likely to be touched
or disturbed then you probably do not have to use armored cable.

 

Indoor
Outdoor Cable

 

Another
style of cable that offers an armored or non-armored construction is Indoor
Outdoor Cable. This type of cable typically has a black UV resistant outer
jacket as well as moisture blocking material in the Kevlar or aramid yarn of
the cable. There are two different types of indoor outdoor cable that you can
use. One is known as distribution style and it will have 900um tight buffer
like the indoor distribution cable we talked about above. Indoor/Outdoor
distribution is the same construction as the above mentioned distribution cable,
except it has a special black UV rated jacket to protect the fibers inside from
the sun’s rays.

 

Indoor
Outdoor is also available as a Dry Loose Tube construction. This is where the
fibers have a 250um acrylate coating only, and they are arranged in separate
buffer tubes with 12 color coded bare fibers in each tube. These are similar to
the next category – Outside Plant Cable, but they do not contain any water
blocking gel, hence the name “Dry”. Similar to the distribution style cable,
this type of cable can be armored or non-armored. The armor used in the cable
is aluminum interlocking armor. This type of cable cannot be direct buried, but
the armor gives the fiber some extra protection in rugged environment settings.
Oftentimes installers will use this when they need to run indoors and some
distance outdoors as well. Rather than needing an interconnect box at the
building entrance to transition from outdoor to indoor cable, this type of
cable can be run in conduit outdoors and then be brought inside without
transitioning to an indoor rated cable.

 

This
type of non-armored cable can be used in multiple applications because it is so
flexible in the ways that it can be deployed. Since you can run this cable
inside or outside, some contractors will purchase this type to keep on hand
because they can use it for a variety of applications. This allows them the
flexibility to handle multiple situations without having to carry several
different spools of cable.

 

Outside
Plant (OSP) Cable

 

Outside
Plant Cable is a cable construction that typically has gel or Icky Pic coating
the bare fibers to give it extra water blocking protection. OSP cables are run
either underground or in aerial applications. These gel filled cables can only
be run inside a building up to 50 feet because of the toxicity of the fumes and
smoke produced when it burns. Building codes regulate this distance and the
cable run will need to be inspected once it is installed. The way that this
cable is installed will help to determine if you will need armor or not. Aerial
and buried applications can use either armored or non-armored outdoor fiber
optic cable. Here we will focus on when the cable is buried in the ground.

 

When
you talk about outside plant cable being buried, you have a couple options as
to how you can accomplish the installation. The first option has to do with
non-armored cable and involves the use of conduit or innerduct. When you are
running conduit underground an armored fiber is not needed but can be used if
desired, because it will give the cable extra ruggedness and it will help with
locating the cable later.

 

Armored
outside plant cable is made so that it can be direct buried and it does not
require the use of conduit. This type of cable construction uses corrugated
steel tape for the armoring. When you bury the cable, please know how deep the
frost line is in the area where you are located because the cable will need to
be buried below that line. The cable is buried below the frost line so it isn’t
damaged when the ground freezes and “frost heaves”. Not only is armored cable
suitable for direct burial, it is also used for rodent protection. So if you
have rodent trouble, it would be wise to use the armored cable. Keep in mind
that the armored cable will need to be bonded and grounded for protection from
lightning strikes, especially when it is used for an aerial application.

 

What
does bonding and grounding the cable do? Basically, bonding and grounding an
armored fiber optic cable protects the cable and the equipment that it connects
to from electrical currents such as current from faulty or exposed wiring or
lightning strikes.

 

Although
this article does not go into the details of all applications, it does give you
an idea of a few different cable constructions as well as armored versus
non-armored applications. Please remember that when you are doing fiber optic
cable installs, whether it is your first time or if you are a seasoned veteran,
you should make sure to do your homework on the geography of the location where
you will be installing, as well as mapping the path where you need to do the
installation.