Coax picking up voltage

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Old 06-15-18, 01:21 PM
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Coax picking up voltage

Hello everyone

i donít know a whole lot about electrical so posting this here and hoping this has an easy fix rather then calling in an electrician.

Ive had internet connection issues since I moved into this new house where connection drops randomly and I have to unplug the coax cable finger it and put it back in for internet to work again.

I had had a Comcast guy come in and check out the connection and he saw no issues with the model or the line. He did say he picked up voltage on the connector and when we went outside to check the cable box there was a good bit of voltage.

Im attaching the picture of meter+cable box in this thread. Is there something setup wrong here that I can correct to fix this connection issue?
Pic


thank you.
 
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Last edited by ray2047; 06-15-18 at 01:38 PM.
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  #2  
Old 06-15-18, 01:52 PM
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I can't tell from the picture, but the outer (shield) part of the coaxial cable should be grounded. It may be grounded inside the house. On my Spectrum (formerly Time Warner Cable) install, they installed a coaxial grounding block (similar to the one to the left of the electric meter in your picture) and connected a wire from it to the house ground wire (near the electric panel). If the coaxial cable is grounded, you shouldn't be getting any voltage on it.
 
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Old 06-15-18, 02:13 PM
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Looks like a ground wire running to that block mounted on the siding between all the boxes. I don't like all those apparently un-terminated cables I see.


I had a similar problem at my old place even though there were all the normal grounds present outside. Solved it by grounding the case of my PC to a cover mounting screw on a metal outlet box in the wall behind it. A few feet of 16 ga stranded automotive wire and a couple of crimp on terminal lugs....0 voltage from cable shield to house ground.
 
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Old 06-15-18, 03:53 PM
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So, is this something that should be corrected by cable company (Comcast) or do I need to bring an electrician at my expense?

thank you.
 
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Old 06-15-18, 04:49 PM
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Originally Posted by Gunguy45 View Post
Looks like a ground wire running to that block mounted on the siding between all the boxes. I don't like all those apparently un-terminated cables I see.
You're correct. In looking closer at the picture, I see a green wire that appears connected to the coax grounding block. Assuming the green wire is connected to a good ground, the coax cable should be grounded.

Originally Posted by Gunguy45 View Post
I had a similar problem at my old place even though there were all the normal grounds present outside. Solved it by grounding the case of my PC to a cover mounting screw on a metal outlet box in the wall behind it. A few feet of 16 ga stranded automotive wire and a couple of crimp on terminal lugs....0 voltage from cable shield to house ground.
If the power cord on your computer has a 3-prong plug, I'm surprised that the computer case wasn't grounded. That's the purpose for the third (ground) prong. The ground wire in the computer power socket should be connected to the power supply case. Since the case is bolted into the chassis, that should ground the case.
 
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Old 06-15-18, 04:56 PM
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Originally Posted by Zombie2k View Post
So, is this something that should be corrected by cable company (Comcast) or do I need to bring an electrician at my expense?

thank you.
I would suggest that you contact Comcast and explain the issue and request that they send out a technician to correct the problem. Hopefully, they won't send out the same technician as before. If he saw that there was a problem, I'm surprised that he didn't try to correct it. Do you know what two points he was measuring voltage between? I'm assuming one point was the outside (braid) of the coax cable. I'm guessing the other point may have been the metal case for the electric meter. If that's true, then something is not wired correctly. Either the coax cable isn't grounded properly or the electric meter box isn't grounded (unlikely).
 
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Old 06-16-18, 02:16 AM
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I'm surprised that the computer case wasn't grounded.
It was...and I even visually checked the attic and saw a straight run from the outside splitter to the room. Don't know why (and I have 24 yrs electronics experience, incl specialty bonding and grounding training) but there was around 350-500mV difference between the shield and the homes ground.
 
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Old 06-16-18, 02:19 AM
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The only problem with calling comcast is, unless you have the inhome service plan, you could be looking at an $80 visit if they want to be snitty about it. Normally, except for initial hook up from the wall jack, their responsibility stops at the outside demarcation point. At least every company I've had, that's the policy.
 
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Old 06-16-18, 06:37 AM
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<< So, is this something that should be corrected by cable company (Comcast) or do I need to bring an electrician at my expense? >>

Neither. Do it yourself. See reply #3 on how to do it using a separately run single conductor (wire).

The ground wire needs to be bonded to the equipment chassis. If there is no sure connection through a plastic equipment case or cabinet, the shell of the coax jack to which you are attaching the cable in question is a good place to connect the ground wire also.

For some reason, my gut feeling is that the coax coupling mounted between the electric meter and the other boxes on the wall might not be adequately grounded. Some tests involving long single conductor wires as meter test probe extensions to get second opinions with would be desirable to be sure. I would not trust a ground wire end squashed between the back of the meter box and the wall to be a good enough ground connection; officially such a ground wire would need to be bonded to the neutral block inside the meter box.

Have you measured and seen readings of voltage between the coax coupling and the meter box?

One cop out to circumvent questions and meter tests regarding grounding is to summarily run a ground wire (#14 will do) from the coax coupling outside in to the breaker panel ground block or bus bar. Should the newly run ground wire first reach a fat ground wire emanating from the panel and going to the cold water pipe as the latter exits the house or going to a ground rod, the new ground wire may end and be attached there.
 

Last edited by AllanJ; 06-16-18 at 07:35 AM.
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Old 06-16-18, 07:20 AM
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I would bet money that the green wire connected to the coax grounding block is connected to some questionable at best ground point.

I've seen a clamp used to the exterior metal of the meter box. I don't know what kind of clamp it is, but it definitely needs to pierce through any paint or rust.

You could add a second grounding block and actually ground/bond it to your main panel, that would work as well.

With the voltage difference, something isn't bonded correctly.
 
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