Ground loop from Cable installation

You might have an unsafe cable installation. You need to have your cable ground checked out before you go in and mask it with a ground isolator.


Call the cable company and tell them that you have hum when you connect your cable and someone told you that you might have an unsafe ground. If they balk then ask them if they would rather you call and ask the electrical inspector to check it out. They don't want that.


If you are handy and feel comfortable checking this stuff yourself, go outside and find where the cable enters the house. There should be a cable "barrel connector" with a ground wire coming off of it. Check all of the connections. The ground wire should connect to the grounding rod coming out of the service entrance. This insures that the shield on the cable is safely grounded and that it is grounded at the same potential as the electrical service ground.


Sometimes even though this is done properly (and this has happened to me) if you've got a big house and long cables, you can still have ground loop problems. Make sure that your cable box and preamp/receiver are plugged in the same outlet. If that still doesn't solve it, then you can safely install one of these isolators. They work.


DO NOT install a cheater plug (3 prong to 2 prong adaptor)!

Most input cables are grounded adequately. A ground loop is formed when you have some other path to ground in the system that is not at the exact same potential and a lateral connection between the two forms a "loop" antenna, thus the term, ground loop.


You should be able to eyeball the cable ground to see if there is one and if it goes to something suitable. If it goes to the big, ten gauge or larger wire that the phone company uses, then it is not the cause of your problem, even if such a connection might not technically meet the current code specification.


Once you determine that the cable input is grounded, there is no more practical way to make the hum go away than with a ground loop isolator. I've bought over a dozen of the Holland product linked above, and I paid a lot more than that price for them. They work just fine. Such devices do NOT in an way defeat the safety of the exisiting grounds. They are not ground lifts. They just disrupt the superfluous lateral connection that completes the loop.

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I have run across this twice in my houses. The first time, I "eyeballed" the ground connection at the service entrance and it looked fine but when I wiggled it, it came apart in my hands. I reconnected it, tightened down the screws, and retaped it. The ground loop hum went away and it has been fine. The second time, I checked the ground and it was fine. I needed the ground isolator. If you're seeing ground loop problems, you must be sure that the cause is not that your cable ground is missing or is not secure before you go putting in something that will mask a potentially dangerous problem.


The above poster is correct that it is safe if you install the isolator at the service entrance but if you install it after a splitter or two, you can have a floating (or high resistance to ground) shield which can be a hazard.

I have a Pioneer Elite VSX-29TX receiver to which I have a Scientific Atlanta 8300HD hooked up (digital coaxial cable out from the cable box digital out directly into the receiver's digital in).


This setup worked for 9 months and delivered audio for all of my channels whether they were analog, digital or hd. Over the last several months I have experienced no sound at all on any channel when I turn on the TV and cable box. It used to be I could unplug the cable box and reboot and that would fix the problem. That stopped working and I had to call the cable company (Adlephia) for a reset signal. That worked for a while and now neither of the above brings the sound back. It comes back on its own sometimes and sometimes doesn't. If it comes on when you first turn on the box, it usually will not cut out. Adelphia has been out several times and said it may be the cable box. It was swapped out but still no audio. They then said it may be the receiver.


When the sound works, the receiver as set to "auto signal select" says "auto-digital". When it doesn't work, the "auto signal select" says "auto-analog". It seems that it can't recgonzie the digital signal coming out of the box. Usually when this happened, my DVD player (Panasonic SD97) would provide a digital signal and audio. Now when the cable box does not provide sound, neither does the DVD.


I have the Panasonic PHD7UY 50" hooked up via HDMI so as this is a monitor there is no sound from the TV - only sound from the receiver. I have not tried rca cables out of the cable box to see if this would work but I really want to use the digital cable so it doesn't matter if it works or not.


Has anyone experienced this problem. Are there issues with the digital out on the box or with the signal provided by Adelphia. I just bought a new receiver (Pioneer 1015) to test out the sound but have not opened the box yet.


Any ideas. Would an optical cable work instead. Is this a ground loop problem of sorts. Thanks.

I have a Pioneer Elite VSX-29TX receiver to which I have a Scientific Atlanta 8300HD hooked up (digital coaxial cable out from the cable box digital out directly into the receiver's digital in).


This setup worked for 9 months and delivered audio for all of my channels whether they were analog, digital or hd. Over the last several months I have experienced no sound at all on any channel when I turn on the TV and cable box. It used to be I could unplug the cable box and reboot and that would fix the problem. That stopped working and I had to call the cable company (Adlephia) for a reset signal. That worked for a while and now neither of the above brings the sound back. It comes back on its own sometimes and sometimes doesn't. If it comes on when you first turn on the box, it usually will not cut out. Adelphia has been out several times and said it may be the cable box. It was swapped out but still no audio. They then said it may be the receiver.


When the sound works, the receiver as set to "auto signal select" says "auto-digital". When it doesn't work, the "auto signal select" says "auto-analog". It seems that it can't recgonzie the digital signal coming out of the box. Usually when this happened, my DVD player (Panasonic SD97) would provide a digital signal and audio. Now when the cable box does not provide sound, neither does the DVD.


I have the Panasonic PHD7UY 50" hooked up via HDMI so as this is a monitor there is no sound from the TV - only sound from the receiver. I have not tried rca cables out of the cable box to see if this would work but I really want to use the digital cable so it doesn't matter if it works or not.


Has anyone experienced this problem. Are there issues with the digital out on the box or with the signal provided by Adelphia. I just bought a new receiver (Pioneer 1015) to test out the sound but have not opened the box yet.


Any ideas. Would an optical cable work instead. Is this a ground loop problem of sorts. Thanks.