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#160436 - 04/04/06 04:10 PM Low voltage wiring in High voltage trench
hdtvluvr Offline
Junior Member
Registered: 04/04/06
Posts: 4
Loc: Tennessee
I need to have some Cat5e and RG6 cables installed. It is in a location that will require them to be installed outside. I am having 2 new 220V circuits added (one for a well pump) and was told by my electrical contractor that the same ditch could be used for the low voltage stuff as long as they were in a separate conduit and separated with 6 - 12 inches of dirt.

The 220v circuits will be in their own PVC conduit 24 inches down. Will the 2 conduits and approx. 12 inches of dirt be sufficient to prevent interference in the low voltage wiring? Thanks!
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#160437 - 04/04/06 07:00 PM Re: Low voltage wiring in High voltage trench
gfretwell Online   content


Member
Registered: 07/20/04
Posts: 9039
Loc: Estero,Fl,usa
More than enough. If you had them duct taped together you wouldn't see any interferance between 60hz and CAT 5. The raceways provide electrical separation too.

The main reason for separating buried utilities is so one guy can dig his stuff up without whacking the other guy's stuff.

[This message has been edited by gfretwell (edited 04-04-2006).]
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#160438 - 04/04/06 07:14 PM Re: Low voltage wiring in High voltage trench
JoeTestingEngr Offline
Member
Registered: 11/04/05
Posts: 781
Loc: Chicago, Il.
Frankly, I don't see an issue with induced noise from the 220 ckts. I might see a hum issue depending on what you're planning to have on both ends of the RG-6. If you are running baseband composite video, which I doubt, you might find yourself in need of an EQ DA. The EQ DAs have a differential input as opposed to a single ended or unbalanced input for the non-EQ DAs.
Joe
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#160439 - 04/05/06 10:04 AM Re: Low voltage wiring in High voltage trench
hbiss Offline
Member
Registered: 12/16/03
Posts: 886
Loc: Hawthorne, NY USA
When I worked for cable the companies doind subdivisions and developments we put coax in the same trench with 12.5kv primaries. Trench was 36" wide, primary on one side, 120/240v services in the middle, our stuff on the other.

-Hal
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#160440 - 04/05/06 11:46 AM Re: Low voltage wiring in High voltage trench
hdtvluvr Offline
Junior Member
Registered: 04/04/06
Posts: 4
Loc: Tennessee
Thanks for everyone's help.

Joe
I'll be using the RG6 for DirecTV and/or Cable feeds (up to 2.5 GHz). Is this baseband video?
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#160441 - 04/05/06 02:49 PM Re: Low voltage wiring in High voltage trench
JoeTestingEngr Offline
Member
Registered: 11/04/05
Posts: 781
Loc: Chicago, Il.
You are fine then because you are dealing with RF. Imagine hooking one end of the RG6 through a phono plug adapter to your VCR video output. Then imagine hooking the other end into the video 1 input of your neighbor's TV/monitor, three houses down. It would be quite likely that you would see a nasty bar traveling up through the picture. That's because there could be a sine wave on both center and outer conductor, when viewed from the receiving end. A differential amplifier will cancel most of that out because it is "common mode" hum. A single ended or unbalanced amplifier will faithfully reproduce the hum with the video.
Joe
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#160442 - 04/06/06 05:45 PM Re: Low voltage wiring in High voltage trench
techie Offline
Member
Registered: 05/17/05
Posts: 246
Loc: palo alto, ca usa
Make sure that you are using cable designed for underwater use. as you can assume that any underground conduit will be flooded at least some of the time, if not most of the time.
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#160443 - 04/07/06 09:27 AM Re: Low voltage wiring in High voltage trench
hdtvluvr Offline
Junior Member
Registered: 04/04/06
Posts: 4
Loc: Tennessee
>>Make sure that you are using cable designed for underwater use.<<

The cat5e cable I have is just standard cable. My RG6 may actually be RG6/U but I'll have to check. I've never seen any Cat 5e for underwater use. If I glue all of the joints on the PVC conduit, why should I expect it to be flooded some if not most of the time? I assumed the PVC would be water tight like it is for water lines.
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#160444 - 04/07/06 09:46 AM Re: Low voltage wiring in High voltage trench
Ron Offline
Member
Registered: 03/13/02
Posts: 582
Loc: White Plains, NY
A wet location is defined by the NEC as "installations underground ..."
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#160445 - 04/07/06 09:50 AM Re: Low voltage wiring in High voltage trench
hbiss Offline
Member
Registered: 12/16/03
Posts: 886
Loc: Hawthorne, NY USA
The "U" in RG-6/U does not stand for Underground.

-Hal
_________________________
www.myphonetechs.com
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