Correct answer: Community Forums - grounding my Cat6 and Coax?

Rut · ‎11-04-2009

Hey again folks. Project is coming along. Just when I think I have thought of it all, every so often I stumble upon more info that raises a question.

I have a cable grounding question. First, the scenario so the particulars are known:

My home is a two-story (split-foyer). ONT and related will be on bottom floor in a closet, and the only easy way to get the cable runs to the rooms is up a wall (inside it) and into the attic, and then drop down into the individual locations (inside the walls).

I am using RG6 quad shield and Cat6 UTP.

The cabling never leaves the inside of the home.

As far as number of runs... 8 for the RG6 and 19 for the Cat6, with the longest run being 75 ft.

Am I required to ground these runs? If so, how?

I read that "shielded" cable should be grounded, but haven't found anything on the unshielded like I have purchased. What about the coax I purchased... it's shielded obviously, right? "Quad-shield". Should it be grounded?

Like I said, the ONT will be inside my home, in a closet, right next to a grounded 120v/15a receptacle.

Thanks for any thoughts.

Regards,

Rusty

HarleyDog · ‎11-05-2009

Rusty,

First, I wouldn't get too hung-up on this conduit thing. Just how many 120 volt electrical cables are in this particular wall cavity? And is it/are they just passing through holes from one stud to the other for a total length of about 14-1/2 inches? If so, your cat6/coax wires will cross them at a 90 degree right angle. This will not cause ANY issues with your LAN or your TV signals. The coax that you're using is quad shielded (which is almost overkill, but a good idea) which will keep out any electro-magnetic interference. And the Cat6 cable consists of twisted pairs which are designed to cancel out and reject any interference. A bad design would be if, for example, the electrical cables were going from bottom to top of the wall cavity with your cables running right next to them. I've actually seen untrained or lazy installers run cat5/6 and/or coax from one end of a basement to the other by using cable ties and securing their cables to a 240 volt electric range circuit! The network and TVs still worked fine! About the worst thing you can do is to drape these cables on top of a fluorescent light fixture!

I'm actually concerned that you'll do more harm then good by using this conduit. The cut ends of the conduit are sharp and need to be provided with a bushing to protect the cable entering and exiting the conduit. You need to be sure that you're not over-filling the conduit, too. The National Electrical Code has tables in the back that list the amount of conductors that can be installed in particular sizes and types of conduit. There is no table for Cat5/6 or coax but there is a maximum percentage of area fill. You take the cross-section of the interior of the conduit (listed in square inches for each conduit size in a table) then you multiply that by the percentage allowed. Then you go to the manufactures web site and look for specs that list the cross-section diameter of the cable in question, add them up so the total amount of cables doesn't exceed the allowed cross-section fill amount of the conduit and there you have it!! All of that work, time, effort and potential for cable damage for no good reason at all!!

Second, don't get too hung up on the grounding thing and here's why: The National Electrical Code, as I told you before, requires all of these systems that enter a house to be grounded to the same reference point. That's because they all have something in common - they're metallic conductors which conduct electricity. The grounding is to protect from damage to the system(s) and to prevent fires, all caused by lightning. The lightning, contrary to popular belief, doesn't have to directly strike the house or the cables. Lightning is such a high voltage that by induction these strikes are sent along the wiring and need to be shunted to the earth. Verizon FiOS has one thing different from all of these other systems: It's non-metallic. It's made out of glass fibers. These fibers do not conduct electricity and they are totally immune from lightning strikes and electrical interference. The techs from Verizon are well trained. If the water line is copper he may ground to that. However, I've not seen your house so I can't really comment.

As far as drilling holes in the top and bottom plates: don't worry about structural damage. It is the studs that carry the load (if it's even a load-baring wall). Think of duct work or return air space for forced-air heating & cooling systems. They remove the entire 14-1/2" x 3-1/2" plate between the two studs! Again though, that pesky electrical code! To protect cables from damage caused by nails and screws used to attach drywall, baseboards, crown moulding, picture hooks, shelving units etc. the code requires that cables are kept 1-1/4" away from the face of the stud. Since a stud is 3-1/2" wide, and 1-1/4" x 2 = 2-1/2", then that allows you to drill a 1" diameter hole in the center of the plate! However, in new construction you can drill a larger hole and protect it with a nail plate. In new construction the cables must be attached to the studs every few feet, in the center of the stud so they're 1-1/4" away from the front and back surfaces. Your wires will be fished and hanging loose. That will automatically protect them from puncture by screws or nails through the drywall if somebody hangs a picture or a shelving unit because the loose cables will just move out of the way. The point of concern is where your cables go through the bottom and top plates. But you know your house better than I. I'll assume that the baseboard are already installed so it's your call.

If it was my house I would probably drill five 1" diameter holes. Two for the Cat6, two for the coax and one spare. I'd fish a string through the spare hole and firestop that hole with mineral wool which is removable. I would forgo the metal conduit and I'd trust the tech for the grounding. (I wouldn't trust the tech if it was the cable or satellite company, but that's another forum!). I wouldn't bother grounding the patch panel because it's isolated on the piece of plywood.

Be sure to use Cat6 patch panels and outlet jacks (I'm a fan of Leviton QuickPort). Cat6 is not just a "cable", it is a system. Every component needs to be Cat6-rated in order to have a Cat6 network.

I don't know if you've ever fished wires before but there are some neat tricks you can do using chain and a short piece of wire with a hook bent on the end or a long, skinny magnet attached to a flexible metal stick. If you need any tips, ask.

And by the way, there is such a thing as a free lunch. Sadly it's usually how you get food poisoning! You probably can't pay back this forum unless you learn something from your experience and can help someone else in the future. But any kind deed that you do in the future, either here, on another forum, or in person counts!

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VZ_Brett · ‎11-04-2009

Hey Rut. UTP cable is Unshielded Twisted Pair . No need to ground the cable. If you are punching the cable down to a patch pannel that will be in a rack or something then just ground the rack. As for the RG6 I beleive the splitters have a ground lug on them that you could run to the ONT ground after the FT installs it.

Rut · ‎11-04-2009

Thank you Brett. Yep, terminating the cables on a patch panel. I'll have the tech show me where to ground them to then.

Thank you much for the help.

HarleyDog · ‎11-04-2009

Hello Rut,

It's good to see that you care about doing a proper and safe installation. The National Electrical Code requires any electrical, satellite, cable TV, telephone, or antenna wiring ENTERING the house to be properly grounded to a Grounding Electrode (typically the water line entering the house along with a driven ground rod). All of these systems need to be grounded to the same reference point. Typically, the phone company or cable company will attach their ground wire to the ground wire of the electrical panel. This is where the Verizon tech should be attaching his ground wire. You DO NOT need to ground the UTP Cat6 or the RG-6 Quad Coax. The "F" connector on the Verizon ONT is bonded (grounded) internally to the ground wire that Verizon will be installing. An additional ground to a splitter or ground block on the RG-6 could cause a ground loop. If you install any equipment racks or structured wiring cabinets the metal frames or enclosures need to be grounded to the same place that the ONT is being grounded to.

I've read your other post regarding fire stopping. You can buy fire stop caulk or foam at the local big box store. Wherever you drill "up" to get into the wall cavity and wherever you drill "down" to get into the wall cavity is where you need to install the fire stop material. Make sure you use a product that is designed for, and won't harm, the insulation on your cables. The Cat6 and the coax should have something along the lines of these words printed on the jacket every few feet: CM, CL2, CL3, Riser. If it has any of those markings it is rated for "in wall" use.

You should not have a problem passing the 120 cable at a right angle. It's only when you run the wires parallel to each other that you'll have problems. However, if you say that you have a section of the wall opened up, and that you can get a section of conduit in the wall, by all means go for it. But the ONLY conduit that will do any good would be steel conduit. Aluminum is non-ferrous and plastic won't do anything against EMI either. But "thinwall" (EMT) conduit will shield the cables from interference. I would rather see you run a section of Carlon Resi-Gard 2-inch diameter orange flexible PVC conduit from your "telecom" closet to the attic. But don't put ANY cables in it. Run your cables in the wall next to the conduit. The 2" Carlon will be for the future - for those cables that you forgot about or the technology that hasn't been discovered yet or that you're not using right now. In two or three years you'll thank me!

Good luck!

HarleyDog

Master Electrician

CEDIA Certified Designer

CEDIA Certified Advanced Level III Technician

Rut · ‎11-05-2009

HarleyDog,

Wow, thank you kindly sir. Absolutely wonderful information that reaffirms many things I kind of thought might need to occur, but just didn't know for sure where to look for the true scoop.

Good to know about the metallic conduit. I would only need a few feet, so I am definitely making the effort on that one. I think it will be worth it. Thanks for the advice - I was planning on just getting PVC, so good to know that would have been a wasted effort against the EMI concern. I'll make sure I purchase the thinwall EMT as you suggested.

The question (of many) that leaves me awake at night though is how many cables can I fit in 1"-1.25" conduit? Probably not many. So then I thought well heck just use big conduit. But I don't want holes any bigger than 1.5" in my sole plates (for structural concerns of course). So I am still contemplating how to do that. I will have 11 runs of Cat6 and 5 runs of RG6. Use multiple conduit runs perhaps? Your suggestion of an empty conduit run in there too is great, and I will try to incorporate that as well. Just kind of feeling like I might need three runs of conduit though... (?) Or at least three runs at the location of the 120v line I mentioned. Hmm, I don't know. Can't imagine it would be good to have three 1.25" holes in a sill plate, all in the same stud cavity...?

On the grounding issue... I am actually having the tech place the ONT, router, backup bat, etc. all in a closet that really isn't close to where the power comes into my home. It's probably 15-20 feet away, but across a hallway and on a different wall of the home. I did indeed show the tech this location (he was at my home last week). He gave it a thumbs up, so I have proceeded with my prep. But the grounding info I have been reading, including yours, has me wondering if he will be grounding it properly. I also will have a 24-port patch panel, and will be using probably no more than 10 or so of those ports at any given time for phone and internet. That patch panel will be mounted with a metal bracket to my plywood wall where also the ONT will be. Do I need to ground the bracket or patch panel in some way?

How obvious is it that I am not an electrician? Ha.

I am simply hoping I can place my trust in the Verizon technician, and he shows up and helps me solve these issues on the day of installation. I hate waiting until the 11th hour though. It's a closet that I chose when thinking of my desired network needs, not necessarily thinking of things like grounding. I will say it is also where the water line and water pump power line runs through the home (through concrete block, below grade). And this will be right where he brings the fiber in too. They are installing on Nov 12, so trying to be completed and prepared.

All and all, your response has me well on my way to making some more progress. Thank you much. Excellent info and I appreciate you sharing the expertise. I've heard there's no such thing as a free lunch, so if I can ever find a way to repay this Forum for all the help, I surely will. Maybe someday I will have some knowledge to share. Bound to learn something through all this. 🙂

Cheers,

Rusty

HarleyDog · ‎11-05-2009