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Posted By: hdtvluvr Low voltage wiring in High voltage trench - 04/04/06 11:10 PM
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!
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).]
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
Posted By: hbiss Re: Low voltage wiring in High voltage trench - 04/05/06 05:04 PM
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
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?
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
Posted By: techie Re: Low voltage wiring in High voltage trench - 04/07/06 12:45 AM
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.
>>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.
Posted By: Ron Re: Low voltage wiring in High voltage trench - 04/07/06 04:46 PM
A wet location is defined by the NEC as "installations underground ..."
Posted By: hbiss Re: Low voltage wiring in High voltage trench - 04/07/06 04:50 PM
The "U" in RG-6/U does not stand for Underground. [Linked Image from sundance-communications.com]

-Hal
So if I glue all of the joints, water will still penetrate the PVC pipe?

What does the U stand for in RG-6/U?
Over the years condensation will collect in the raceway with no easy way to get out.
I suppose if you blew hot air through the pipe occasionally it would stay dry but nobody does that.
They do make wet location cables tho. They are just a little more expensive.
In real life regular low voltage cable would probably work if you were real careful not to damage it while you were installing it but it is not "supported" by the standard.
Posted By: hbiss Re: Low voltage wiring in High voltage trench - 04/07/06 08:27 PM
Water will get in no matter how well you glue the joints. Another source is condensation.

What does the "U" stand for? Nothing of any consequence. Underground RG-6 type cable will have a grease or other goop under the jacket. Same with CAT5.

-Hal
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