Alleviating current flow between CATV ground and electrical ground

Electric-Light

Senior Member
There is an installation where there is a few volts of difference between the system ground. The CATV shell and power-line ground on my TV are connected internally.

This causes a few amps to flow between the TV and the CATV line which causes visible moving horizontal bands on screen.

Signal strength isn't great, so I didn't want to add anything to the CATV line that would attenuate the singnal, so I connected every equipment connected to the TV behind an isolation transformer.

Is this the correct approach? How do you guys usually deal with this?
 

Little Bill

Moderator
Staff member
There is an installation where there is a few volts of difference between the system ground. The CATV shell and power-line ground on my TV are connected internally.

This causes a few amps to flow between the TV and the CATV line which causes visible moving horizontal bands on screen.

Signal strength isn't great, so I didn't want to add anything to the CATV line that would attenuate the singnal, so I connected every equipment connected to the TV behind an isolation transformer.


Is this the correct approach? How do you guys usually deal with this?

Is the CATV ground tied to your GE system?
 

hurk27

Senior Member
Sounds like you might have a bad or weak neutral connection between the pole and your service, the cable coax is bonded both at the pole and at the house and parallels the service neutral, if the service neutral has a voltage drop then the coax starts having more and more current on it, if the service neutral run is long then this can be normal and the cable company should put a shield isolator on the drop, but if the service drop is short, I.E. not longer then 150' then you have a neutral problem, and if this problem has recently just popped up, then it is a connection that is going bad, I did have one house that the owner upgraded the panel but not the service, and the drop to the house was only a #8, and the new panel was badly unbalanced causing a high neutral current, but the problem with the cable was caused by this, and the cable company refused to hook up till it was fixed, which we did.
 
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