AVS Forum banner
Status
Not open for further replies.
1 - 11 of 11 Posts

·
Registered
Joined
·
157 Posts
Discussion Starter · #1 ·
when i casually mentioned to a home depot dude that i was dropping cables through my walls, he said i should definitely drop the cables attached with some steel wire. he said if i didnt, gravity would eventually cause the cable to stretch and that would be evil.


now, the theory makes sense to me, but i am wondering if its something i should really be concerned about. if its going to take 50 years for the cables to stretch to the point that i start noticing ill effects.... well by then i probably wont be in the same house, and the cables will be outdated anyway.


right now i only have coax rg-6 quad shield and rotor wire on a 3 story drop and cat 5 ethernet on a 2 story drop. but i may drop more in the future


its dropped through an outside wall, and insulation and other factors make running or rerunning more than necessary a pain. so i dont really want to have to rerun the wires with steel wire


~Zippy!
 

·
Registered
Joined
·
807 Posts
I'd think you're fine. I have a bundle of about 8 CAT-5 cables dropping two floors (second floor to crawl space) and they're working fine for two years now. Seems to me that CAT-5 isn't all that heavy and should be able to support itself for a 2 or 3 story drop. Looking on the inside, each cable has a very tough non-stretchable thread inside it (not sure what material is used for that, but it clearly is there to provide stretch resistence). So, me thinks it's no problem.


-Rob-
 

·
Registered
Joined
·
30 Posts
I believe that most rg-6 has a steel core, so you should be fine. FWIW I have a 4 rg-6 lines going from my dish area to my crawlspace, which is about a 35 ft drop.


Rob
 

·
Registered
Joined
·
17 Posts
Most cad5 cable has nylon string that runs along the inside of the cable that stops the cable from stretching, so I think it would be fine to run the cable up two storys.
 

·
Banned
Joined
·
3,181 Posts
i sell wire to contractors everyday for horizontal as well as vertical runs....


NO ONE supports the wire like your salesman suggested....


the only time that a steel cable is added to a cable is if it is to be strung outside between poles....
 

·
Registered
Joined
·
19 Posts
Don't worry about it, any problems would require heat or mechanical force.


It's much more important not to kink or bend the cable to tight. This will cause a change in the carefully-designed geometry of the cable and as a result change the characteristic impedance of the cable. Result - tweaked signals, reflections on the line (worse the higher the frequency) and similar gremlins.
 

·
Registered
Joined
·
1,112 Posts
As far as I've been tought, that little nylon string is called the "rip cord", and was designed to make it easier to split the insulation to expose the wire- simply make a small slit in the end, grab the nylon cord, and pull!


I've NEVER heard of that being used as a structural member, nor have I ever seen a cable with that nylon cord attached to the end in any way.



Think about it- Say you have a 200 foot Cat5 cable, and for some reason, you wish to hang it off the side of a tall building. Unless you are HANGING something off your cables (which you should NEVER do, unless it's a super lightweight microphone or something designed for that purpose), you would be replicating the "abuse" of hanging a cable in your house. Even if that nylon cord *WAS* attached at the ends, it would do very little for the strength of the wire, as the wire itself is only attached at the ends as well. The weight of the wire would still be largely unsupported (try *pushing* a wire, instead of pulling it- see how well that works?).


Now, there might be some custom wiring that is internally strengthened, but I've never seen it, certainly not for home theater wiring.



RG6 is very strong stuff, you don't have to worry. We lowered an old C-Band dish (metal dish along with a steel frame to hold it) 2 stories with it's piece of RG6 when we repo'd it a few years back. Now, I'd never reuse that cable, but it certainly wasn't in any danger of degradation from it's own weight.


- David
 

·
Registered
Joined
·
764 Posts
I think you're fine without additional support.


For what it's worth, per 2002 NEC 300.19, vertical supports for copper power wiring, #18 through #1/0, shall be provided at maximum intervals of 100 feet. The distance is shorter for bigger wires (drops down to 40' max intervals for 750kcmil). That info is not directly comparable to your situation, but it might be useful as a guideline or sanity check.


You're dropping 60 feet or less. I wouldn't be concerned.
 

·
Registered
Joined
·
764 Posts
Some other thoughts:


I'd be more concerned about the stress at the bend or termination at the top of the riser. Try to take the stress off of any such bend or termination. Even a mickey mouse solution, like tape or string, would be better than putting the full weight of the cable on a hard 90 or a crimp connector.


Also, you might check the websites or call engineers at your cable manufacturer, or at a major manufacturer like Belden or Anixter. I'm positive that they would have specific recommendations on maximum allowable tension.
 

·
Registered
Joined
·
1,237 Posts
that string id called a zip string.its used to split the sheath not for keeping the cables from stretching. they do have plenum cable which is made for drop wire long distance but dont worry about it.. hes prob heard of people droping string for pulling another wire..
 
1 - 11 of 11 Posts
Status
Not open for further replies.
Top