Cable TV Line Grounding - AVS Forum
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post #1 of 19 Old 03-09-2009, 02:17 PM - Thread Starter
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I'm having a problem with a drive line on my TV that I assume is being caused by a ground loop somewhere. My cable line doesn't have a ground at the house - it comes directly from the in-street box (where it is grounded) into an indoor splitter with no break in the line. I thought I would start by grounding it at the splitter to a cold water line, specifically the washer feed which is next to the splitter. Is this a good idea? Do I need to get a separate component or can I just take ground off the splitter where there is a screw which I assume provides ground.
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post #2 of 19 Old 03-11-2009, 03:13 PM
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Quote:
Originally Posted by spearhead View Post

I'm having a problem with a drive line on my TV that I assume is being caused by a ground loop somewhere. My cable line doesn't have a ground at the house - it comes directly from the in-street box (where it is grounded) into an indoor splitter with no break in the line. I thought I would start by grounding it at the splitter to a cold water line, specifically the washer feed which is next to the splitter. Is this a good idea? Do I need to get a separate component or can I just take ground off the splitter where there is a screw which I assume provides ground.

Yes, that is a good start, and no additional components are needed; just some wire and a water pipe ground clamp.

Let us know if it doesn't clear your issue up.

Matt

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post #3 of 19 Old 03-11-2009, 03:16 PM
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Quote:
Originally Posted by spearhead View Post

I'm having a problem with a drive line on my TV that I assume is being caused by a ground loop somewhere. My cable line doesn't have a ground at the house - it comes directly from the in-street box (where it is grounded) into an indoor splitter with no break in the line. I thought I would start by grounding it at the splitter to a cold water line, specifically the washer feed which is next to the splitter. Is this a good idea? Do I need to get a separate component or can I just take ground off the splitter where there is a screw which I assume provides ground.

To meet NEC standards, it has to be grounded to the electrical service ground. There is a discussion and references here:

http://www.hometheatershack.com/foru...grounding.html

Yes, calibration is important...every user should be calibrated.

Need electronics repair? A great place to start looking for a shop in your area: http://www.tvrepairpros.com/
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post #4 of 19 Old 03-11-2009, 03:32 PM - Thread Starter
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That link points to a page that says I have to be grounded at the entrance to the home. Does this mean I should cut the cable and insert the ground at the point where it enters the home? It currently has no break from the street until it's well inside the house. Does Comcast understand this? It seems that they should have provided the ground connection if it is at the service entrance.
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post #5 of 19 Old 03-11-2009, 06:27 PM
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Comcast knows this and if you call them and insist they will likely do it at no charge.

Yes, calibration is important...every user should be calibrated.

Need electronics repair? A great place to start looking for a shop in your area: http://www.tvrepairpros.com/
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post #6 of 19 Old 03-15-2009, 08:50 AM
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Yeah Comcast HAS to ground the line coming off the pole outside before it enters the house. It is within their own interest and and yours fro both legal and performance reasons.

Call them and press the issue, they cannot charge you since this is needed to meet National Electric Code.
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post #7 of 19 Old 03-26-2009, 11:49 PM
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I've been wondering the same thing. The other day a Cox guy came out to check the lines, and he actually removed a coax grounding block! It was just hanging loose, not connected to anything. So recently I got a dual grounding block (since I have two lines coming in), but I have no place to ground the block other than a metal pipe coming up out of the ground through which come the incoming cable lines. Does anyone know if I could attach the grounding block to that? I would assume, that cable lines are gounded at the main incoming service box.

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-Clint
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post #8 of 19 Old 03-27-2009, 04:58 AM
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Call Cox and tell them that they need to ground it. It should not be your problem. I work with Cox all the time here and I was in BR much of my life and their policy is to ground each system according to code. You do have a place to connect it, where every other system is supposed to be grounded to, and that is the electrical service ground electrode. It may be distant or inconvenient, but it is not your problem. The will do it. If they refuse, have the person you are talking to contact their supervisor. Once you get to a supervisory level and they find out that your system is not grounded they will get it done. The need for doing it properly is simply not subject for debate.

The old Cablevision that was in BR before Cox bought it did not ground most installations until sometime in the 1980s. They had so many problems and got burned on damage to customers' systems so many times that they finally started to ground everything properly. Cox has always done so as long as I have worked with them and will usually correct it when they find it not done properly. It is one thing that they have been pretty good about.

Yes, calibration is important...every user should be calibrated.

Need electronics repair? A great place to start looking for a shop in your area: http://www.tvrepairpros.com/
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post #9 of 19 Old 03-27-2009, 09:31 AM
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lcaillo, thanks for the info. You don't think it's already grounded at the main service box?

God Bless,
-Clint
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post #10 of 19 Old 03-27-2009, 01:33 PM
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Clint, I have no idea. The implication in your post was that it needed to be grounded. If it is then why are you worried about it? If it is not, get them to do it.

Yes, calibration is important...every user should be calibrated.

Need electronics repair? A great place to start looking for a shop in your area: http://www.tvrepairpros.com/
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post #11 of 19 Old 03-28-2009, 03:10 AM
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Originally Posted by lcaillo View Post

Clint, I have no idea. The implication in your post was that it needed to be grounded. If it is then why are you worried about it? If it is not, get them to do it.

No implication was intended. It was a question. You said you worked with Cox, so that's why I asked: "You don't think it's already grounded at the main service box?" That's the only logical explanation as to why the recent Cox guy removed the existing (hanging) grounding block and didn't properly attach it. I don't know, that's why I asked.

God Bless,
-Clint
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post #12 of 19 Old 03-28-2009, 04:19 AM
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How is someone other than you going to know. Just check. There is no logic to whether a particular employee does his job or is lazy. If he was doing his job he may have removed it because it was not needed and old and corroded. If he was lazy he may have removed it simply to eliminate possible connection problems in the system and did not go back and connect it if it was needed. How can you find out...go look to see if there is a ground wire connecting your cable coax shield to the electrical service ground...I can't speak for others here, but my clairvoyance fails me.

Yes, calibration is important...every user should be calibrated.

Need electronics repair? A great place to start looking for a shop in your area: http://www.tvrepairpros.com/
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post #13 of 19 Old 03-28-2009, 05:11 AM
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Originally Posted by lcaillo View Post

How is someone other than you going to know. Just check. There is no logic to whether a particular employee does his job or is lazy. If he was doing his job he may have removed it because it was not needed and old and corroded. If he was lazy he may have removed it simply to eliminate possible connection problems in the system and did not go back and connect it if it was needed. How can you find out...go look to see if there is a ground wire connecting your cable coax shield to the electrical service ground...I can't speak for others here, but my clairvoyance fails me.

Forget I even asked. I can't check. The cable to the house, comes out from a vertical metal pipe, which comes up from concrete. The lines are buried under concrete, then under ground, until they come to the large metal Cox "service box" in a neighbor's backyard.

Therefore, I have no idea if the lines are grounded or not. Since you have said, and others have said: CATV should be grounded; and since I have said the Cox guy removed the hanging (not even grounded) grounding block, the logical explanation (assuming he's not incompetent, giving him the benefit of a doubt), is that the lines are already grounded. Maybe they are, maybe they are not. I DON'T KNOW.

Therefore, deferring to your (or so I figured) greater knowledge on this, I asked you since you said "I work with Cox all the time here". If you don't know, then fine, all you had to do was just say that.

God Bless,
-Clint
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post #14 of 19 Old 03-28-2009, 04:08 PM
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You can easily check. Just measure the resistance between the cable shield and the a.c. ground with the cable disconnected from your set, surge suppressor, box or splitter. If you have more than a few ohms you have a grounding problem. There is simply no way to know if they did it right or not without checking. I relayed my experience with Cox, which is they have a policy of doing it right, but they also have lazy and incompetent field techs, just like every other cable company. You can assume this or that or ask but there is no way to know without checking.

Yes, calibration is important...every user should be calibrated.

Need electronics repair? A great place to start looking for a shop in your area: http://www.tvrepairpros.com/
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post #15 of 19 Old 03-29-2009, 07:10 AM
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Originally Posted by lcaillo View Post

You can easily check. Just measure the resistance between the cable shield and the a.c. ground with the cable disconnected from your set, surge suppressor, box or splitter. If you have more than a few ohms you have a grounding problem.

When you say the "cable shield", is that the same as the metal connector? Since all cables have connectors, I don't know how else to get the metal braided shield.


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I relayed my experience with Cox, which is they have a policy of doing it right, but they also have lazy and incompetent field techs, just like every other cable company.

Yeah, I understand that.

God Bless,
-Clint
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post #16 of 19 Old 03-29-2009, 03:06 PM
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Yes, the connector is connected to the shield in the cable. If a connector is properly installed and not loose, it sould be at the same potential as the cable shield. That should be the same potential as the electrical service ground. i.e. no significant voltage nor resistance between them. A few ohms or a few tens of millivolts is not a problem.

Yes, calibration is important...every user should be calibrated.

Need electronics repair? A great place to start looking for a shop in your area: http://www.tvrepairpros.com/
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post #17 of 19 Old 03-30-2009, 01:07 AM
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Originally Posted by lcaillo View Post

Yes, the connector is connected to the shield in the cable. If a connector is properly installed and not loose, it sould be at the same potential as the cable shield. That should be the same potential as the electrical service ground. i.e. no significant voltage nor resistance between them. A few ohms or a few tens of millivolts is not a problem.

Thanks. Ok I checked it using a nearby grounded extension cord (the ground wire hole) to the main cable in connector. I got 2.4 ohms. So I guess the cable is grounded.

God Bless,
-Clint
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post #18 of 19 Old 03-30-2009, 04:59 AM
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Did you disconnect everything from the cable line? If you did that is fine. If not, you could be getting ground through a surge suppressor or other component. 2.4 ohms through an extension cord is good, as you have some resistance in the cord and in the connections to it, as well as the circuit to the outlet and the connections at the service.

I recommend that you find the ground connections at the cable drop and the a.c. service and verify that they are clean and tight every year or so. The corrode and get loose over time.

Yes, calibration is important...every user should be calibrated.

Need electronics repair? A great place to start looking for a shop in your area: http://www.tvrepairpros.com/
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post #19 of 19 Old 03-30-2009, 05:16 AM
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Originally Posted by lcaillo View Post

Did you disconnect everything from the cable line? If you did that is fine. If not, you could be getting ground through a surge suppressor or other component. 2.4 ohms through an extension cord is good, as you have some resistance in the cord and in the connections to it, as well as the circuit to the outlet and the connections at the service.

Yeah I disconnected the main coax line from where it goes into the house. So there was nothing at all connected to the line.


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I recommend that you find the ground connections at the cable drop and the a.c. service and verify that they are clean and tight every year or so. The corrode and get loose over time.

Well I could do that at the AC service, but I doubt I could at the cable service. Since like I said, it goes into a large locked metal box in my neighbor's back yard.

Thanks a bunch for the help. I learned a simple way to check to see if your cable is grounded, and as always I will pass that knowledge along to others that need to know.

God Bless,
-Clint
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