Indoor versus outdoor fiber. We have seen people use fiber cable that was built by the manufacturer and only warranted by the manufacturer to be used inside of a building. It wasn't ever built to be used outside of a building and it won't last for very long. The big thing that will happen to fiber cable that's not rated for outdoor use is two things: sun damaged, sun will damage the outside of the sheath of an indoor fiber cable very quickly, the other thing is water intrusion. So water will get in the pipe if it's an indoor fiber cable. It's not built to repel that water so the water gets inside. There is a couple of different types of fiber: one is loose tube and the other is a tight buffer. And that's the way the glass is packaged inside the cable and the way it has coating on it. And I think we have some examples. And finally there's armored cabling versus all dielectric cabling. Armor is simply a metallic element inside the the cable that protects the fiber optic strands against rodent damage, against rats chewing or rats or mice. Now one of the advantages of optical fiber is glass is not conductive. So you know many of you live in regions where lightning is really really common. If you have metal between two buildings and one building gets struck by lightning, believe me, voltage will be carried on the metal going between those two buildings and it can kill people in the other building if it's not properly grounded and bonded on both ends. Here's some examples of some indoor fiber cable packages. Notice the one on the right, you can see you know there's a blue fiber and orange fiber that this is a example of a tight buffer cable where it's 900 microns of plastic covering the glass. Here is an outdoor loose tube armored cable. It's outdoor because it's black and it's rated by the manufacturer to be used outdoors. You can see the armor on it is the shiny piece and then the optical fibers are carried inside of a tube. So you can see an orange tube and a green tube there. Likely each of those tubes has 12 fibers in each one of them. Now each fiber is still coated with some plastic but it's only coated with an additional 125 microns of plastic. So the glass is 125 microns and they make it be 250 microns by putting a little bit of plastic on it to protect the glass and to make it to where that plastic is colored so you'll have the normal color codes of blue, orange, green, brown, etc. So here's some additional fiber cables and you can kind of see what the construction is. Now here's an example of loose tube versus tight buffer. Tight buffer, you can directly terminate each fiber, is in a 0.9 millimeter buffer, there's no gel, it's bigger and sturdier, you can get it both in the indoor and outdoor packages and you can terminate that directly onto a fiber connector. Loose tube, there'll be buffer tubes. So the buffer tube is the green thing that's kind of shown as a zoom in there and inside that will be a number of fiber cables, a number of fiber strands that'll be 250 microns, so very, very small and they'll be typically gel filled. So there'll be a water blocking compound there. It's very water resistant. It's a nice very good type of fiber cable. And this is what, typically, all of the telephone and long-haul internet service providers use is a is a loose tube fiber cable. If you use loose tube fiber cables either they must be directly spliced onto a pre-terminated pigtail if you're going to do direct termination. You must use this furcation kit which takes the 250 micron fibers and slides it into these 900 micron empty tubes. So again -- label your fiber cable. Label it at each end. Label at every place you have an access to it. What kind of fiber is it, where it comes from, where does it go to, how many fiber strands. Let's talk for a minute about fiber slack loops. Fiber slack loops are very important because of two reasons. One reason is if you ever want to make changes in your fiber cable and maybe you have some, you've installed a 24 fiber cable where it's going to a single building and now you want to break it out and take it to another building. So another very important reason for slack loops is repairing fiber if you have a fiber cut. And my favorite story is one of my first trips to Africa. This was almost 20 years ago. I was talking to some folks from a university. I'd done a much simpler version of all of this talk and they said: "oh, you know, we have a cut. We had fiber that ran across the street and they were doing some civil works in the street and they ran into this pipe. They didn't know what it was so they cut it with a saw and they looked and they saw it was fiber and about the same time as we realized that we had lost connection to that part of our campus. And we ran out there and lo and behold the guy had just cut it with a saw. And how do we fix that?" And my first question to them was "Do you have any slack loops?" And they said "No". So the only way to fix this is either you pull new cable, you repair the conduit and you pull new cable or you have to put multiple vaults and do multiple splices and it's not a simple thing. If you have slack loops then it's pretty simple. What you do is where the fiber was cut, you're going to install a hand hole or a vault at that cut location. You pull slack from the adjacent building so that you have the fiber coming out of the hole. You simply have your contractor or maybe you're ramped up to do this yourself, you splice the fiber cable back together. You put the splice case in the hand hole, you cover it up and you're done.
© Produced by Philip Smith and the Network Startup Resource Center, through the University of Oregon.
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