Cat 5 between buildings

[Unregistered]

I would like to run cat 5 from my house to a building ~280 feet away. My concern is lightning protection. What type of issues are there with grounding and two different power sources between the two buildings? Also, how deep should I bury the conduit? Should I only ground the cat 5 at the building where it connects to the switch or should I ground it at both ends? What is the best way to ground cat 5 in this situation?

Thanks

[mdshunk]

There's no conductor inside of the Cat5 cable that gets grounded. Instead, there's a "bleed off" terminal on the lightning arrestor that gets connected to ground at each building. It wouldn't hurt to put a lightning arrestor at each end, since there's no electrical connection (inside the Cat5 cable) between the two ground terminals on the lightning arrestor. Remember, you need a lightning arrestor for each pair. If you're using ordinary Cat 5, this would mean you'd need 4 lightning arrestors (or 8 if you're doing both ends). Better yet, since you mention "switch", I assume that this may be part of a PBX type system. You may want to use a bonafide "Cook Block" at each end, which has awesome plug-in replaceable type lightning arrestors and a built in punchdown block.

Generally, PVC conduit is run for phone cables. In my area, the phone company makes us install 2" for underground phone lines. I think this is HUGE. Since this is your own little deal, 1/2 or 3/4 will be fine. Article 800 of the code (which covers phone wiring) says that the conductors should be installed in accordance with chapter 3 (which covers regular wiring). This means that you need to bury 18". Whew!

I generally pull underground Cat5 in conduit. This type of wire normally has a black sturdy insulation, and the inside conductors are very greasy. This type of wire is often referred to by the old-time name of "icky pick". You can change to regular cat 5 at the first punchdown inside each building.

See the pic below of the "Cook Block" and the plug-in lightning arrestor modules. Note the handy in and out punch down blocks. The pic is of the 66 style, but you can get them in 66, 110, and BIX and Krone punchings.

[Unregistered]

Thanks for the info. Do you know of any problems with current running over the buried cat 5 that is being caused by grounding between two unbonded systems? The two buildings are on different electrical systems and I will just be grounding each end to each buildings electrical system. I have read about the possibility of different potentials existing between the two grounding systems that may lead to current flowing between the two grounds. What I have found so far is an ethernet connector that takes two RJ45 connectors and has a ground wire coming out of the device for connection to the grounding rod. Would this work just as well with one of these on each end? Thanks again for all your help.

[mdshunk]

Hopefully someone will pick up the ball from here. That question is getting out of my realm.

[suemarkp]

I was going to ask what you were using this cat5 for -- phones or ethernet. You mentioned ethernet so that helps. I believe MD's answer is still correct for ethernet -- the pairs are each differential circuits and I don't believe either side is grounded. Only a shielded cable would have a ground. But if some uncompliant computer (or if I'm ill informed of how cat5 is really done), you could have a grounded conductor. This could be bad because of the large distance involved and the ground loop that may occur. At least its not RS-232 where the signals are unbalanced and a different ground reference can cause voltages way over what you expect.

Some other issues. There is a maximum cable length for cat5 ethernet and I think its just over 300 feet. You're getting close to this limit. Having run video this distance, I know ground loops can be a horrible problem. I think your best solution is fiber between the buildings. The fiber termination kits are now inexpensive, and the UTP to fiber media converters aren't too expensive anymore. Just go with multimode fiber -- way cheaper and easier to work with than single mode. You could even buy a custom length terminated fiber cable and pull it through a 3/4" conduit. This solves all problems.

If you must stay with wire, I think the connector you have will help with lightning issues. But I don't believe lightning will be much of an issue for buried wires between buildings. Run this overhead on a messenger, and I'd definitely use that RJ45 with the ground pigtail. I'm still afraid of a potential for ground loops, but I have no experience to back this up. You said things are unbonded, but I doubt the electrical services are ungrounded. If each is grounded, there will be a voltage difference in the earth between them. How big depends on the feeders supplying the buildings and how the whole distribution system is designed.

[Unregistered]

Thanks, considering the fact that the RJ45 grounding units are $65 a piece I would prefer to spend that money on fiber to ethernet converters. My only concern with fiber is just how delicate is it? I would prefer to just purchase a 100m terminated length and let the slack sit at one end of the building to avoid having to terminate myself. Is fiber so delicate that it could potentially break just coming off the role or does it take a decent amount of stress to hurt it? I am looking at some fairly inexpensive 100m SC-SC fiber but I would hate to order and pull it, only to find that it was damaged at some point and worthless. I may also run a piece of RG11 between the buildings for satellite tv feed so I suppose I could attach these two together for the pull and hope that most of the tension will rest on the RG11!! Thanks again for all your help. One last thing, is the bend radius for fiber greater than cat 5?

[mdshunk]

My experience with fiber causes me to believe that it's not nearly as fragile as one may be lead to believe. It is plastic inside (not glass), and is very flexable. Of course, you don't want to yank it or kink it, or it will be ruined. The bending radius is about 12" for most purposes. You can shine a flashlight in one end and look for the "white dots" at the other end for a quick and dirty test after you've pulled it. A good slow supervised pull (one man pulling and one man feeding) is all that's generally necessary. Often, we go about 3 conduit sizes bigger for a safety factor. One, two strand fiber regularly gets 1-1/4" conduit.

[suemarkp]

Its not all that fragile, especially in tension when you are pulling by the insulation. Kink it hard, and it may break. Your biggest worry is feeding terminated ends through the conduit -- you may pull the connectors off if that is your pulling member, or they may fold back and snag. So try to keep the connectors pointing straight ahead, leave the dust caps on, and tape the fiber to a pulling string a foot or so back from the terminations (but lightly tape the connectors to the pull string to keep them forward). Also, pull all your cables at once or at least do the fiber first.

There should be nothing wrong with buying an excessive length of duplex 62.5u fiber and just coiling it up near your switch.

[Jacksnap]

Have you considered wireless? 280 feet is not a problem as special antenna's involved and readily available. Connection can be secured with good encryption setup. You can use it either as a network only, or network/internet access or just internet access. Here's a web site that can give you more information.
http://www.fab-corp.com/index.htm
Just another solution to consider.
Jack. :)

[southernrain_nc]

I too would recommend using conduit to run the 'Icky' cat5 wire if you opt not to go wireless. Also, at each end I would install a power strip with a built in protected network jacks for lightning protection. For long distances, eg over 300 feet, a cheap router on each end helps boast the signal. Good luck.