Sign in with
Sign up | Sign in
Your question
Closed

network cabling for outdoor use

Last response: in Networking
Share
November 19, 2003 8:17:32 PM

I want to run a network connection out to my garage from my home ethernet 10/100 network, but not sure what type of wiring/cabling I should run between the buildings. There is 75' between the buildings that will be exposed to the outdoor environment and I am unsure whether just using a cat5 twisted pair will tolerate the exposure. Wireless is no option for me as i am tired of buying new equipment for simple tasks.
Any suggestions from anyone?

Thanks....
tc
November 20, 2003 7:05:20 AM

the only thing to worry about is maybe interference. then theres the remote possibility of lightning hitting the cable. but its more likely the cable will be destroyed before it gets to either network device.

wpdclan.com cs game server - 69.12.5.119:27015
November 20, 2003 7:06:05 AM

if your really worried about it, just get some pvc pipe and run the wire through that and burry it

wpdclan.com cs game server - 69.12.5.119:27015
Related resources
November 21, 2003 4:50:10 PM

At 75' you have a large opertunity for signal degregation just from the internal resistance ofthe wire. Also if it comes any where close to power wires at that length or other communication wires for that matter signal degregation can result. A good option although more expensive is to use STP ( sheilded twisted pair) you can find this from places like mouser.com or allied electronics. PVC conduit can be bought at any hardware store in the electrical section. Be sure to glue the pvc conduit. This would not necesarily have to be barried. If worried about lighting in an application where it isn't burried then the UTP or STP with a 10-8 guage bare ground wire which can be easily found at hardware stores also. finally if you use STP be sure to localy ground the sheild at either end. To save some money you can use telephone grade two pair twisted pair sheilded wire at half te cost of STP since 10/100 only use 2 pairs of the 4 any ways except in 200mhz biderectional applications. also if you use 4 pair you can double up the communication wires to lower the internal resitance of the wire although this has little effect on the impedance. If you look hard enough you can find UV resistant for exposed use or direct burial type of wire. Then again it might be cheaper to get WiFi

Windows is prettier! Linux Is better!
Anonymous
November 23, 2003 2:01:06 PM

Great post, and the idea about the heavy guage drain wire in the sheild, seems like it is/could be a good one. I have a couple questions for you about your post though.

About the grounding scheme...

1. By grounding the STP at either end, ie the PC, you are creating a path for the energy from the lighting to flow through the PC. Is that really a good idea?
2. With even a 10-12 AWG guage drain wire will the STP have enough current carrying capacity in the sheild to effectively shunt lightning to ground?

Regarding the bit about 75' resistance errors...

I thought the ethernet standard states there is 300meters in qualifying hardware before there is any signal degradation in the absence of any crosstalk or interference.
November 24, 2003 2:57:38 AM

the sheild wire is certainly not meant to protect against lightning and that was not what I was suggesting. That is why I suggested using a large guage ground wire also for an overhead application although I did not clearify that.
The longer the run of wire ie:75' the larger your area for accepting interference is, if interference is available. A long run of wire will act as an antennea. And yes UTP does pick up radio FM or AM signals and AC. Of course you don't hear it since the signal is digital and is filtered out usally before or after being amplified by the opamp, but what it does do is reduce the signal-to-noice ratio which reduces the theoretical max bandwidth. Lengths as little as 10' will pick up such interference. In fact it is suggested to use "Individually Sheilded Twisted Pair" cable for use with T1 where the cabling distance is greater than 10'.
I am referencing the following article because I could be a little misleading http://www.dcbnet.com/notes/0301t1.pdf Obviously the application probably doesn't call for the full 100Mbps so you can get by easily with a lesser solution.
I tend to over do things like some mad over clocker when I do wiring jobs.
If you have access to a Fluke networking cable tester like I got to use back in school, that would be the best way to determine what the actual through put is.
Your sheild would also not have to be connected directly to the PC either. It can be connected to the ground of an outlet thus dissapating the charge to ground and not the PC or any equipment.

Linux Is better! www.killeramp.com
November 25, 2003 2:36:50 PM

Ok, after reading all this you have to be confused and overloaded with information.
Your simplest solution is this:
You can go with PVC piping which is great and cost effective. When you put your joints on, you'll want to use a recommended sealant which should melt the plastic together forming a leakproof tube. Only problem, moisture.
But you are able to run Shielded TP or unshielded (at 75', you're not going to be picking up any interferance that will cause you any problems unless you're digging a ditch under an electrical grid, running electrical wires along side your TP (twisted pair), etc. Attenutation (signal degrading) at 75' is nothing. Most companies run cables well over 75'. I ran UTP through a PVC pipe 110' without a problem, certified it at 100MHz and was able to run at 100Mbit without a problem. (Although I won't fail to mention the person whom I was doing the work for didn't take my advice on having his piping sealed correctly and having it buried 12 inches down, it filled completely with water.)
Get your PVC piping with UTP and run in. You can run out to a hardware store or talk to a plumber and ask them what you can use to reduce moisture build up in the piping. Make sure everything is sealed properly to keep rainwater out. Bury the piping 6-12 inches down which will reduce any interference. If you're really concerned about the possibility of interference, compare pricing between Shielded Twisted Pair (STP) and metal piping. The metal piping will negate most interference like the STP would.
The only other thing you'll want to do is run a "draw string" or another cable so you're able to pull the line through. You may someday want to run additional lines through, so add a cable in there so you can pull more cables through.
My advice: UTP with PVC sealed correctly, talk to someone at sears or a hardware place to find out how to reduce moisture. Depending on the humidity and rainfall in your area, this can be a small problem or a big problem, thats for you to decide since we don't know where you live. :) 
I've done runs like this many a times, you can trust what I'm saying from experience, not from guessing/assuming it.
Any other questions/problems, post here and we'll do what we can to help you out.

Riser
November 25, 2003 8:44:47 PM

Thanks guys.... you all have been a big help if not very interesting in your techniques. now i guess i'm off to the hardware and other wiring outlets to search for and price the different hardware approaches suggested. Just one more question, would using a outdoor phoneline (following the correct shielding specs) with rj45's connections at either end instead of rj11's work at connecting a dsl modem to this network hub i'm trying to set up in the garage?

always looking for alternatives,
TC
"Thanks again"
November 25, 2003 9:36:24 PM

Technically yes, as long as you wired it up correctly.
Cat(egory) cable is a twisted pair, with so many twists per inch which reduce the amount of attenuation (signal degrading) and interference you receive.
Technically, if wired up correctly it will work, but at possibly at 10mbit, which is all the modem can do anyway.
You can give it a shot, I know someone who networked their entire company using their phone lines instead of running cable. This was before 100mbit was even thought up though.

Riser
Anonymous
November 26, 2003 11:43:11 PM

Hi riser,

It sounds like you have good practical experience with doing this stuff. I wonder if you'd mind commenting on a couple of things your post brought up for me.

You said that UTP in a well glued PVC tube would work. Is that really going to be lightning proof and safe for the user/hardware? I can see it being OK if it's burried when it's like that. I think just laying that configuration across the surface would be unsafe.

Personnaly I like the metal pipe idea, but you should definitely remember to earth that baby!

Finally, have you ever run into an application where STP was necessary to get this "100MHz certification" you mentioned? If so could you give a couple of details about it?
Anonymous
November 26, 2003 11:54:19 PM

you said:

"the sheild wire is certainly not meant to protect against lightning and that was not what I was suggesting. That is why I suggested using a large guage ground wire also for an overhead application although I did not clearify that."

Yeah man I understood what you said. Maybe you misunderstood me. Check out sheilded cables with *drain* wires in them. You'll find that they are like a regular shielded cables, but with a large gauge bare/exposed wire laid against the shield, and running down the whole length of the cable. This results in a very large current capacity shield. In my post I was musing whether the added current carrying capacity was sufficient for good lightning protection.

Good point about just making the point of grounding away from the PC. Maybe at the exterior wall of the house? What do you think?

<P ID="edit"><FONT SIZE=-1><EM>Edited by knewton on 11/26/03 05:56 PM.</EM></FONT></P>
November 27, 2003 3:25:04 AM

If I'm thinking of the cable you are refering to the gauge of the drain (usually the same gauge as the condutors)is not sufficent for a direct hit by lightning.

Grounding for lightning at the exterior of the house for lightning is more than a must.

Besides many homes have a grounding/lightning rod in the way of an TV antenna which is usually the highest point around which the lightning will hit first. The obvious thing to do if you were running overhead would be to use an existing powerline running from garage to house (Keep in mind that you should never use "The Utilities" wires as these carry higher voltages and second you should be qualified even when dealing with your own power wires)if it exists as this has several benefits:
1. it is already grounded to earth ground
2. It is physically strong to edure the force of wind, and the weight of snow and ice.

If you can go underground you don't have to worry about anything execpt breaking your back digging a ditch. If you live in a northern area you want to go below the frost line. Here in West Virginia it is 18in. If any water gets inside your conduit it will freeze and bust it. And the great thing about conduit is it allows you to run wires after you've installed it theoretically.
Of cource all this depends on what kind of work you like to do.

Linux Is better! www.killeramp.com
November 27, 2003 3:56:33 AM

An advantage of using Individualy sheilded pairs is that the wires do not have to be twisted. Twists in the wire add attenuation to the signal in three ways:
1. more twists means the more wire length used per foot of cable and the further the signal has to travel.
2. even though the wires are wound in opposite directions around each other their is still plenty of field to introduce an impedence (frequency reactence or a type of resisitance that is directly porportional to frequency of the signal traveling through the wire)
3. all coils (which is exactly what the twists are)have capcitance. This allows the signal to create a high resistance short circuit. this is known as capacitive reactance. This is where coax has advantages for long runs.

The twists in the wire serve to reduce cross talk, the signal from one pair crossing over to the other pair. A sheild does this much more effectively without problems 1&2 above.

The shorter the distance and the lower the frequency the less these things are factors.

I'm not completely sure though about where to ground sheilds, because if you are not careful you can also create ground loops which can oscillate. This is the case when product developers go cheap and isolate their grounds or when the power cord does not have a ground plug. But the safest place is always earth ground.

Linux Is better! www.killeramp.com
November 27, 2003 1:01:44 PM

Lightning hitting your cat5 cable is very unlikely.
You really won't have a cable that is safe against lightning. STP (shielded) doesn't protect against lightning either, the shielding actually protects it from getting interfence from running the line with electrical wiring through a building. If lightning is going to strike, its going to strike and do its damage. More than likely if your garage is struck, the lightning will never have a chance to pass into your cabling because I'm assuming your garage is probably wooden and already grounded. If you bury the cable lightning shouldn't be an issue at all.
I was talking to another guy I work with about this posting. He's running 110 feet of UTP out of his apartment window, down the wall, along the sidewalk and into his garage. He's leaving the wire exposed but used an edge trimmer to get a few inches down along the sidewalk. He moved out into a house about a month ago and the line was still in great condition after being exposed for 2 years.

If you bury the piping/cable down at least 2 feet you should never have to worry about cutting it unless a waterline/gasline/etc breaks, those tend to be buried deeper. Should you have an underground sprinkler system installed, they shouldn't need to go deeper than 12-14 inches to install it.
As far as the use of STP, you can read up on in at this link:
http://www.informit.com/isapi/product_id~{967563CD-A039-47B7-85CB-C5A8485C4644}/content/index.asp
Just over halfway down it will state the uses of STP, mainly used in Europe and what it does.
STP is out of the question, not needed.

As far as certifying wiring, I'll explain this.
If I run a cable 200 feet from point A to point B, I would need to use a cable tester which reports what quality of MHz I get from the cable. You can buy cable like Cat5 which is 100MHz, cat5e which is like 200Mhz, Cat6 goes up to like 400MHz, off the top of my head I'm not sure since its changed so much. Anyhow, if I have cable that can run up to 400MHz, I put the cable checker on both ends, which sends a signal and tells me the MHz I've obtained. You can get a higher MHz by avoiding electrical grids, lighting, etc. If the cable comes back saying I have 370MHz, I would more than likely certify it at 300MHz or 350MHz, meaning that the cable is capable of consistently obtaining that speed and should someone come in to check the cabling, it wouldn't come across as a violation. Does it need to be certified? Only in businesses mainly, at home, I wouldn't worry about it.

Back to the UTP in the PVC piping. PVC piping is used in a lot of plumbing now-a-days, and its safe. I would suggest running the PVC piping because you may want to run additional cabling later or even a coax cable for your TV out that way. I do recommend burying it, it shouldn't be that bad digging 6 inches down, but if you want to go deeper, rent equipment or have a lot of time on your hands.
PVC is probably cheaper than the metal piping, but you wouldn't have to worry about that pipe cracking to breaking should a dump truck need to drive across to dump dirt or stones in your backyard, or whatever :) .

Hope this helps, that website should let you know about STP (and how its mainly used in Europe anyhow).
UTP should be more than enough for what you want, the PVC or piping is recommended, but optional. You can run the line and bury it later or install the piping later. It comes down to how much you want to spend and future expansion into the garage. Dig a ditch once with the piping, 6 months later run a line through the pipes, you're in the clear. Don't laying the piping you might find yourself down the road digging another ditch to lay the line:) 
Good luck!

Riser
Anonymous
November 27, 2003 2:33:44 PM

Right. The fact that Coax was abandoned in favor of UTP/STP has always bothered me somewhat. I'm told by people that work with the stuff that the twisted pair configurations are much easier to troubleshoot and maintain. I guess I can see how the laziness factor counts, especially back when bandwidth was never an issue. As you pointed out though, coax is just better than twisted pairs in so many ways.

PS thanks for the replies. very useful stuff.
Anonymous
November 27, 2003 4:41:18 PM

Yeah lightning strikes are rare, but you can increase the odds of them occuring by creating the correct electrical conditions. For example, lightning rod shaped wire runs are bad.

There are other uses for the sheilding other than the crosstalk/interference issues mentioned on that thread you posted, namely static. Typical sheilding configurations would have a certain amount of static discharge protection, but as has been pointed out in another post on this thread (see TNTom last reply to me), the current carrying capacity of the sheild in your typical STP is suspect when it comes to the question of whether it can properly conduct (to ground) all the energy in your average lightning bolt.

I still like the galvenized pipe idea for surface runs electrically, but would definitely consider PVC for buried runs. It's so much easier to work with.

That cable checker that you are talking about sounds cool. It makes me wonder about how it tests. Do you have any links for these, I want to check them out. It's probably too expensive for a SOHO tech though, eh?

Hey thanks for replying. It just goes to show an old codger like me can stand to learn a few tricks from the pros.
December 1, 2003 7:17:13 PM

We just moved our Nashville, TN. office down the road and we had a company come in to run our cat6 and certify it. He was using this $10,000+ cable tester. I have seen some nice ones, but this beast sat there talking to him, telling him what was wrong, how good the connection and such was. It even had a 2-way radio built in to talk to his partner who was testing the lines. I priced a few for a college I was working at and the best bang for the buck was around $5,600. Expensive, but you can hook these up to color printers and print out colored charts of all sorts.
The only cable testers I've seen by big cabling companies are Fluke, and these are nice. I'm not sure of the extend of Graybar Inc (www.graybar.com), but they rent these testers out at like $50/day last time I checked my area for a small job.
A link to all of Fluke's cable certifying equipment:

http://www.flukenetworks.com/us/Cabling/default.htm#tab...

At the top you'll see a LAN/WAN link, use those to view other products. They should have one in there that does almost all of that stuff, if not you could contact them to talk about it just to see what it costs and what it can do.

Enjoy, just don't expect one for Christmas at the cost of these :)  I'm sure you can find an older used one on Ebay or maybe old stock a company may part with for a few hundred dollars though.

Riser

<P ID="edit"><FONT SIZE=-1><EM>Edited by riser on 12/01/03 04:19 PM.</EM></FONT></P>
!