In this session we're going to talk about underground conduit or pipe that is buried this is often the best way to route cabling between buildings it's kind of tricky to design and it's easy to make mistakes which will make the conduits hard to use so some common mistakes that we see are there's not enough pipes we don't bury enough pipes we dig a trench and we only put one pipe in when we should have put four sometimes we find that the pipes that we've placed the conduit is too small so you know it's 50 millimeters rather than 100 millimeters and another really common mistake i've seen people make is too many bends between the places where you can get a hold of a piece of cable to pull because remember we're gonna we lay these pipes and then we come in later and pull uh cable in them i will guarantee you if you have 360 degrees worth of bend and that's pretty easy you know you go down the street and you turn 90 and you turn 90 to go up a sidewalk and you turn 90 to get to the building and then you turn 90 to get uh up to the second floor well guess what you have 360 degrees of bend and it's going to be impossible to pull cable through there without having an intermediate pull point a place where you can get a hold of the cable and pull on it and we'll look at that a little bit some additional rules here no more than 200 meters between pull points so every 200 meters you need to have if your pipe has just been buried in the ground in a straight fashion you need to have a hand hole or a vault those are the two words that mean the same in the u.s a hand hole or a vault every 200 meters we're going to reduce that distance that 200 meter distance by 50 meters for every 90 degrees of bend right so that means if you have or 90 degrees of bend like in my previous example you can only have zero meters of of pipe which is exactly the right answer you don't never want to do 360 degrees of bend never under any circumstances exceed 270 degrees without a pull point so the way you do this is you survey the site you spend a lot of time walking around looking at it then you'll do the layout and you'll figure out where you're going to place your hand holes or your volts again bigger conduit is better than little uh we always recommend at least one 100 millimeter or 250 millimeter conduits that's to each building and i will point out that conduit for fiber optic cable is different than water pipe and we'll we will look at that really carefully we want uh whoever does the civil works when they're doing the digging to install a pull rope in all the conduits including empty ones and we ought to label the conduits and we'll talk about that here in a second so as you plan this get a map of your campus now if you're if you don't have a really accurate map of your campus you can use google earth and just take a snapshot of the google earth image of your campus you know there's a pretty dang accurate map you'll lay out the conduit paths on this map plan for where your vaults are going to be and don't forget to think about future expansions so if you know your campus is going to build some more buildings we'll make sure that your underground conduits are sized and and you have enough of them so that you can serve those buildings as well so here's a small piece of the university of oregon campus that building in the lower left computing that's where i have had my office starting in 1977 and so that was obviously a core location for our campus and you know again if you don't have this nice really pretty pdf map you can easily take the google earth image this is a google earth image of exactly the same pieces of the campus and then you kind of decide where you're going to lay it out in this case this is just a straw man proposal where i'm going to lay it out um i'm going to come out of the computing building go up by some sidewalks run alongside some sidewalks for a ways and you know kind of proceed my way on now in this case i know that there's a whole bunch of buildings below here uh that you can't see and so i'm gonna plan my conduits appropriately for that so again this is the same thing on the google earth image same image same everything so volts vaults are a way to reduce number of bends the hand hole provides a pull point so you reset the 200 meter rule and the other thing you can do is any place you might branch and go different directions a vault is a good uh thing to place and think about future locations if you if you're running by a place where you know the camp the master plan for your campus says that there's going to be a building built there we'll put a vault there even if you don't need it because of the 200 meter rule that gives you a place to uh to pull cable and serve that building without having to do a whole bunch more digging so in my example here i've called out some conduit counts and sizes and i've showed you where i'm going to place vaults you can see i start out with five 100 millimeter conduits if i'm only pulling fiber cable to these few buildings that are being served believe me i don't need five conduits because a hundred millimeter conduits about this big you can fit uh you know you can fit a dozen or or 15 fiber cables in a pipe that big again this is mostly for the future and you can see i've run four 100 millimeter conduits all the way out to that vault just outside of allen hall and that's going to be where i go to the downward direction to serve the rest of my campus we've harped on and talked about hub and spoke configuration as being the most important design a factor and you you look at this and you go wait a minute that's not hub and spoke you're almost daisy chaining that's true you cannot afford to build your underground pipes in a hub and spoke configuration right underground conduit is installed in a very linear fashion notice again this doesn't help with redundancy in the case that we we just looked at about designing the underground pipes if you cut those pipes right by the computing building our entire network is offline so think about alternate paths and install all two fiber cables to every building one from each direction but you don't have to start out that way redundancy is something you can consider after you've gotten your network installed and operational and people see the value in it and then you can start to talk about hardening it and making it more resilient.

© Produced by Philip Smith and the Network Startup Resource Center, through the University of Oregon.

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