Running Cat5e/Cat 6 Underground - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 9 Old 07-18-2011, 08:09 PM - Thread Starter
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I am involved in a project where I need to run some network cables underground in a Plastic PVC Conduit to tie together 2 homes on 1 property. Is running shielded cable a good idea or will the shield actually cause more of a reason for lightning,etc to find it's way into the wire. I know fiber is best,but more expensive,so not sure it's a solution.

I should also add that One of the cables would be used for an HDMI Baluns device to share video from one system to another.

Thank You In Advance
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post #2 of 9 Old 07-18-2011, 08:33 PM
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I have never done such a project, but in theory there should not be an issue with what you are trying to achieve except but you must be very careful of a "floating ground" which could cause some serious issues.

HDMI baluns do have a limitation on length of Cat5/6 cables, so you should verify with the baluns you plan to buy.

How long will the run be between the 2 buildings for network cables? How tall are the building surrounding the burial site? How are those houses grounded? Do they share a same ground or not?
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post #3 of 9 Old 07-19-2011, 04:16 AM
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I believe you would use underground rated category cable, even in a conduit.

You are probably aware, but don't put line voltage cables in the same conduit.

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post #4 of 9 Old 07-19-2011, 08:57 AM
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Underground CAT5e is fairly easy to source. Look for a VNTC jacket (vinyl). Some of these may be called 'direct burial' cable: do not directly bury, install conduit and run the 'direct burial' cable in the conduit.

Shielded cabling will do nothing for lightning, use incoming surge devices at the entrance to the buildings.
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post #5 of 9 Old 07-19-2011, 07:02 PM
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You can also use 'flooded' cat 5 (filled with icky-pic that oozes out and seals the jacket if it gets nicked). Flooded cable is pretty much the norm for UG communication cables whether in conduit or not.

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post #6 of 9 Old 07-20-2011, 09:41 AM
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OK, u got 100 meters, that's it. Longer than that then it's fiber.
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post #7 of 9 Old 07-20-2011, 02:02 PM
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With HDMI, you usually get ~150 feet, not the 328 with Ethernet. You might be able to get more by using an HDMI system that uses two CAT cables, not one. HDMI from one building to another is an, um, interesting project.
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post #8 of 9 Old 07-20-2011, 02:08 PM
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For long run HDMI you need to look at a Twisted Pair Extender based around HDBaseT - HDBaseT will do HDMI + IR + RS232 + 10/100 Ethernet over a single run of CAT5 or CAT6.

There is a built in 100m limit though you can cascade multiple units to go further if required.


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post #9 of 9 Old 07-23-2011, 10:53 PM
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I am currently involved in an installation where the need for shielded Cat-5e cable is an issue. The conduits linking the main house and pool house were installed and buried prior to my getting involved with the installation. The distance of underground run is only 120' with approximately 90' of the run in the same trench as the feeders to the 200 amp electrical panel in the pool house and feeds to a hot tub. Though the landscaper who dug the trenches and did the pipe work claims he kept the conduit dedicated for low voltage around 3 feet away from the power lines, my tester was doing back flips when testing the end to end pin configuration and showing voltage present.

I am now awaiting for the shielded Cat-5e cable order to arrive to see if this will resolve the problem. If your conduits are also ran near service feeders, you will want to make certain to purchase shielded cable that includes a drain wire. A have been advised the drain should be grounded at only one end of the run. I know this is common with other types installations I have done that utilized shielded cables.
Depending on the amount of current the power wires are carrying, and if motors are involved, there is a limit to what even shielded cable can resolve.

I know that with analog composite video for CCTV over twisted pair, there is also a big concern about ground loop problems when linking buildings with different services / grounding locations. You should have no problem with the data runs but the video might be a problem. I have never dealt with HDMI in such an application so maybe someone else that has can give info.

In recent years, the NEC has required that direct burial rated cables be used even when ran in PVC Conduit underground. The reason is they expect that eventually most conduit runs will be infiltrated with water / dirt and the minerals will have effect on standard cable jackets in time.

Ya don't want to install cable in a way that they may fail several generations down the road

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