Topic: cable tv and grounding

[danhtcfl]

Hi,

I finally found this site while surfing for information about the NEC, Grounding Systems, and CATV Coax shield ground.

Maybe you folks can help. I recently tried to get an extra drop installed in my home in Orlando by Bright House Networks (TWC) to get broadband internet. Bright House contracts out all installations to what I guess are all independent installers.

Well, The installer comes out and I show him where the two current drops connect to the incoming cable via a splitter. The splitter is grounded via a bare copper ground wire that goes into the soil. It then and goes around the side of the house connecting the telephone demarc, cold water spicket (cold water pipe), and finally the power meter. So the cable is the last thing on the line and the power meter is the point of origination.

I thought this was standard and to code, but this Installer tells me that cable company has strict rules and that not only the new drop, but the existing one will need to be moved/re-run from the cable box to the bottom of the power meter and grounded there. I ask why can't we just run a new ground wire directly from the power meter to the cable demarc if there is a concern about the ground. He tells me it (shield ground) has to be connected directly to the meter.

Does this make any since to you? Its a free install so I guess he would be billing the cable company for all the additional work. I just told him to go home and I asked for a different installer to come out this Friday.

Is there anyway I can test/prove using my Multimeter that the ground system is correct?

Thanks

-Daniel

[ February 04, 2004, 03:01 PM: Message edited by: danhtcfl ]

 

[tom baker]

Re: Topic: cable tv and grounding

Your cable tv company is not subject to the rules of the NEC. Howver the NEC does have rules on grounding of the coax shield, see NEC article 820 Part III and IV.
The cable ground does not have to be connected to the meter, the NEC lists several acceptable locations for bonding it.

 

[hbiss]

Re: Topic: cable tv and grounding

Your cable tv company is not subject to the rules of the NEC. However the NEC does have rules on grounding of the coax shield...

Your second statement kinda contradicts the first doesn't it? True, they don't have an AHJ or inspector to enforce compliance but the NEC applies none the less.

The installer who looked at your house is correct. That copper wire that goes all around the foundation is probably only 14 or 12ga. That, coupled with the length make it pretty much useless. This is why the NEC requires that all services (electric, telephone and CATV) enter at basically the same location. This is so that all grounds can be bonded together with the shortest length of wire possible. If this is not done the chances are pretty good that your equipment that you have connected to the service will be damaged or destroyed by lightning (Florida is the lightning capital of the world!) or a power cross. It is also possible that a fire can start or personal injury could occur.

I don't understand your opposition to this. The installer is trying to correct a previous problem. It's not going to cost you anything whatever he does and it's for your own good. What's your problem? ) that some customers were a real PITA with stuff like this. That's not you is it?

 

[hurk27]

Re: Topic: cable tv and grounding

Tom I have to go with HBiss on this one as the NEC does allow for the cable shield to connect to a ground rod. But this new ground rod MUST be bonded with the Power system electrode. with that said. Lightning has AC properties at RF levels that don't travel down single wires very far. and tend to jump off. Most grounding electrode conductor over 25' is useless. as the lightning might not even see it as a good path. The shortest route to earth is always the best and the installer is correct in what he is proposing.
What will happen if not done is lightning will try to follow the in feed to the equipment to get to the neutral of the branch circuit. this is because this neutral is connected not only the the GEC but to many other neutrals that form a rather large array that the lightning can dissipate into. and since the overall impedance of this array is much lower to the lightning than just that little wire running to the service (which by the way will be vaporized in the event lightning should strike leaving the rest of the current to dissipate through your equipment.)
It looks like earth to it.

Here's a good site to read up on this and much more.

Lightning saftey

[ February 05, 2004, 08:50 PM: Message edited by: hurk27 ]

 

[dereckbc]

Re: Topic: cable tv and grounding

My two cents worth. If your existing cable enters the oppisite side of your home that your AC service does. Then the best option IMO is to run a conductor straight down to a driven rod. Then this rod has to be bonded to the AC service GE system. If possible the bonding jumper between rods should be bare. It will form a partial ring conductor.

I agree the best scenerio is to have all services (CATV, water, AC, telephone) enter at the same location to facilitate a single point connection to GE system. It is just not always possible

So if your CATV provider is going to move the service to where your AC enters at no charge, let them have at it. Heck, I would give them a tip.

 

[tom baker]

Re: Topic: cable tv and grounding

This bonding jumper Dereck mentions is required in the NEC to be a 6 AWG copper, this was added in the 2002 NEC, but only for residential applications.

Hbiss, I know what you mean on the contradiction. The real question is who installs it, if the electrician gets the service in first, then the cable TV person comes and puts the protector on the other side of the house? Guess who gets the violation?

Take a look at NEC section 820.40

(4) Length. The grounding conductor shall be as short as practicable. In one- and two-family dwellings, the grounding conductor shall be as short as practicable, not to exceed 6.0 m (20 ft) in length.
Exception: In one- and two-family dwellings where it is not practicable to achieve an overall maximum grounding conductor length of 6.0 m (20 ft), a separate ground as specified in 250.52(A)(5), (6), or (7) shall be used, the grounding conductor shall be grounded to the separate ground in accordance with 250.70, and the separate ground bonded to the power grounding electrode system in accordance with 820.40(D).

[ February 06, 2004, 12:32 AM: Message edited by: tom baker ]

 

[danhtcfl]

Re: Topic: cable tv and grounding

Ok, I'm going to re post this to clarify my language a bit.

I recently tried to get an extra drop installed in my home in Orlando by Bright House Networks (TWC) to get broadband internet. Bright House contracts out all installations to what I guess are all independent installers.

Well, The installer comes out and I showed him where the two existing drops connect to the incoming cable demarc via a splitter. The splitter is grounded via a bare copper #4 ground wire that goes into the soil then goes around the side of the house connecting the telephone demarc, cold water pipe, and finally the power meter. So the cable demarc is the last thing on the ground wire and the power meter is the start of the run.

I thought this was standard and to code, but this Installer tells me that cable company (TWC) has strict rules and that not only the new drop, but the existing cable demarc will need to be moved/re-run from the head-end to the bottom of the power meter and grounded there. Then he would need to re-run all the drops from the new demarc.

I ask why can't we just run a new ground wire directly from the power meter to the cable demarc if there is a concern about the ground. He tells me the demarc has to be connected directly to the meter. The demarc is but I think he may have thought it was just connecte to a grounding rod stuck in the soil.

In the diagram below the current ground wire runs in an "L" shape along the house.

The installer wanted to re-run the cable from the head-end in an upside-down "U" that would go along the opposite side of the house under the driveway and demarc at the meter. He said he would have a crew come out and dig out under the driveway to wrought the new cable.

Here is a diagram.


.........|...............|
.........|...............|
.........|..Drive.Way....|
.....+--------------------+
.....|....................|
.....|....................|
.....|....................|
.....|....................|
Meter|....................|
.....|....................|
..CWP|....................|
.....|....................|
.....|....................|
..Tel|....................|
.....|....................|
.....|....................|
.....|....................|
.....|....................|
.....|....................|
.....+--------------------+
.....................Cable


He didn't speak English well and I don't speak Spanish so I had a hard time understanding him.

Does this make any since to you? Its a free install but I would be billed for all the additional work.

I just told him to go home and I asked for a different installer to come out this Friday.

Call me crazy but the existing cable demarc and ground arrangement was installed as part of the house being built in 86. It must have past inspection then. Wouldn't it be grand-fathered in now?

Is there anyway I can prove to the next installer that comes out using my Multimeter that the ground system is correct? I want to be ready for the next guy in case there are any questions.


Thanks

-Daniel

 

[jimwalker]

Re: Topic: cable tv and grounding

Bit confused.My understanding is the total job of getting your Internet connected is at brighthouses exspinse not yours.They will give you a limited install usually to an outside wall.Just what are they trying to charge you for ?
When we connected to roadrunner i ran my own wires as i didn't want there sloppy work.So if you ran the wire from your computer to just under the meter then they should pick up the install from there.To move the other lines should also be there problem as they were hooked up by them.
The English problem will be hard to fix,a recent visit at your airport proved difficult to find any workers that smoke good english.Trying to find starbucks took 3 tries to get it in english.This problem starts in Miami and is spreading fast.
Them wanting to connect at the meter location is correct but correcting old work should not be on you.

[ February 06, 2004, 11:14 AM: Message edited by: jimwalker ]

 

[hbiss]

Re: Topic: cable tv and grounding

... The existing cable demarc and ground arrangement was installed as part of the house being built in 86. It must have past inspection then. Wouldn't it be grand-fathered in now?

Maybe, assuming it was actually inspected which I doubt. Connecting a ground to a water spigot is not something that the code would endorse.

... Is there anyway I can prove to the next installer that comes out using my Multimeter that the ground system is correct?

No, it's not that simple and that's what we have been trying to get you to understand.

Further, the installer isn't going to listen to or understand anything you have to say anyway even if he did speak english. He's there to do a job the way he was told by his boss. Probably doesn't even know what the NEC is. Besides, the NEC is a minimum standard and the cable company may have stricter requirements. Like I said above, you are in a high lightning area and the cable company can be held responsible when customer equipment and property is damaged by surges entering on their service. They are just trying to protect their butt as well as yours and if they feel it's necessary I wouldn't argue with them.

Now, if they are trying to charge you to re-run the drops I would want to know why. Normally they are responsible for anything outside the house. I would speak with someone directly at the cable company. This shouldn't be your responsibility.