Running Network cable through conduit
Hello all!
A pleasure posting here! I appreciate anyone who may be of assistance to me on this situation. I’ve already browsed a few threads here and it is linked within my post, but none seem to be clear on my particular situation. So my apologies for a duplicate topic.
I’ve been pursuing networking for some time now and have done networking runs in my own home for years. I also do networking for friends/family/church on the side to help folks out, hence why I’m posting. I’ve come across a situation I’ve not had to experience before so here goes:
I have an authorized person at church giving me the o.k. to run a networking backbone for their new wired/wireless infrastructure that I’ll also be installing. Most of it won’t be too dificult, but there’s one part that gives me a kicker. 5 buildings exist with relatively short distances between one another, so not so much an issue with distance runs (I think 325 ft max on Cat5/5e). The shorter distance buildings will possibly have a hard line but preferbly the wifi will take over for the short runs. The issue at hand is that between the furthest run of buildings (about 75-150 ft) has a parking lot between with a small 4-ft wide portion that has been dug up in the past and filled in with gravel (I “suppose” electrical or water or gas “””may””” be ran in there, but not sure. I’ll have to call and find out) to connect the two sets of distant buildings (3 on one side 2 on another). Either way. My question is this. I’ve read tons of websites and articles/suggestions on how to run cables through conduit (gray electrician’s pvc specificlaly). But what has lost me so far is this:
+there’s no concrete standard for how far down to go (most sites estimate min 4″, median 6″, and max 8″, if possible)
+several sites talk about grounding the cables (or pipe?) in case of lightening strike due to the nature of cables being conductors themselves
+filling conduit to only a 40% max and then running other add’l conduits
+using caution tape several inches above pipe(s)
+ground itself will absorb the entrapped heat from cable and over-taxing of cable?
+”The code limits the type, cross-section and number of conductors under the conduit fill, derating due to the number of ‘current carrying’ conductors and applicable tables in section 316″ (from http://forums.finehomebuilding.com/comment/789351#comment-789351)
+and; something about needing surge protectors/ thermal supressors on each end of pipe (connecting what? and connected to what?)
Whew!
The thread on this breaktime forum I read in most detail is :http://forums.finehomebuilding.com/node/116492 titled “running buried cable through pvc conduit”. It had it’s confusion points. But another site helped a tad :http://forums2.gardenweb.com/forums/load/tools/msg0920111726353.html?23. I also use metafilter.com a lot and this particular post helped too. http://ask.metafilter.com/57840. I post these links to give you an idea of where I’m trying to find help from. Breaktime seems to be the best though.
I’m only looking to run 2-4 cat6 or cat5e cables as backbones with possible expansion to 6-10 or so. This gray pipe and walls on insides of buildings will cut through brick/concrete and marked that absolutely no other cabling will be allowed to be run (electric, phone, etc.) in it. I assume they’ll be open pipes and not capped or closed due to heat or expansion. I also already read and will try the shopvac/vacuum technique to run a messenger line (I think that’s what it’s called).
Can someone please clarify the steps and explain some of the questions as best they can. I will be happy to reply with additional info or clarifications.
Thanks a lot!
Andrew
Replies
Can't address all of your issues, but the fact that this is low-voltage, power-limited cable means that most of the rules you quoted don't apply. Since there is no power, they do not count as "current carrying" and there's no derating required. I'm not sure if this relieves you from the depth requirement.
The lightning issue, however, is a real one, and one point where inspectors may become hard-nosed. Especially since you're not using metal conduit, the cables should have lightning arrestors (eg, http://tinyurl.com/3u2aznt) at both ends. These need to be grounded to a good, legal electrical ground.
The other point where inspectors may be deservedly hard-nosed is separation from power wiring. None of you cables should ever enter any enclosure or conduit that is shared with power wiring.
And of course you need to observe fire regulations regarding the routing of wires.
I was in the computer biz for 30 years and 15 of it was in Florida (lightning capital of the world)
My first advice, don't do it. Use fiber between the buildings and put a fiber to copper switch in each one.
If you are going to do this, be sure the grounding electrode system between buildings is bonded together. This is probably best left to the electrician but you want the bonding wires as straight and short as possible.
If you can't do that, We actually pulled a bonding wire between the buildings and bonded the frames of the machines together and put ferrite beads on the CAT 5s. Make the bonding wire short and loop up some extra cable on the Cat 5. That actually worked pretty well in places like pool bar cash registers and other remote machines.
The problem is "ground" is not really always "zero volts" and in a lightning event you can have quite a bit of voltage shift between ground rods on different buildings. I have measured 35 volts or more on my Dranitz voltage recorder. You want to null this out as best you can.
Yeah, the fiber is an excellent idea.
I appreciate y'alls replies. Y'all did answer a good many of my questions, which I apologize again for having so many. Anywho, the breadth to which this project will need to go will far surpass my skill set. I have considered fiber optic but the cost for this low-budget church will be way too much than the budget could ever be. Now I personally know the wonderful, long-term benefits of fiber but they probably won't budge on it. I think this job is still doable but only through wifi capabilities. There will not be a backbone which will weaken the infrastructure and possibly cause the network to malfunction and be quite unstable from building to building (a E4200 per building) on a regular basis.
Again, I greatly appreciate all of y'alls feedback.
Thanks!
Andrew
WiFi may be your best option and the new protocols are pretty fast. With the right antenna you can get out quite a ways.
There are also other radio-based point-to-point solutions.
I'm going to assume you know what you're doing, and will stick with your original plan. Here are some things to consider:
1) Cat-5 usually isn't suitable for outdoors/ wet locations. You may have to buy a box of 'rated' cable (inside buried pipe is a "wet" location);
2) Pulling wire puts stress on it. Cat-5 cable doesn't slide very easy, and it doesn't bend very easy. That's why you never want to use a pipe smaller than 3/4", and larger is better. How often do you want to dig? You also want to use large-radious elbows (known as 'sweeps');
3) PVC pipe is nice, but if you're doing multiple, you need to at least consider using rigid (steel) sweeps, wrapped in 'pipe wrap' tape. This is because your pull string WILL cut through the sweep, and the cable will get caught;
4) You want that pipe DEEP- at least 24"- since that's a traffic area. Dig right, dig once!;
5) Have the pipe come up into the bottom of a proper 'hand hole' or in-the-ground box. This will make your pulls much easier. If the cement cover of the hand hole get broken, replace it with a steel one; and,
6) If you think that they ever might switch to fiber, pay particular attention to the radius of your turns. Fiber is a LOT stiffer than cable.
Have the pipe come up into the bottom of a proper 'hand hole' or in-the-ground box. That's the answer a i want to find. But the word "in-the-ground box" means what? I cann't find the answer in http://www.wifi-antennas.net/ about WIFI antenna
I think the box he's talking about is something like this:
View Image
Amish Electrician
Is he right?
What the Amish don't know about network wiring ain't worth knowing.