This is a question hopefully all the engineers, electricians, installers here can help with. I'm sorry if it is a newb question. I have searched for an answer without any luck and my cable company has been of no assistance.

Here is my setup. My cable comes into my home and is well-grounded at the exterior box. It then enters my home and is split into several homeruns. One of the runs goes to a detached garage where I have set up a home theater. The garage has it's own power supply and it's own ground. Do I need to ground my cable at the entry to this building. I have noticed what I believe to be a slight ground loop while watching my cable (horizontal bar moving slowly from bottom to top barely noticeable to anyone other than me). It disappears when I run my coax through my power conditioner. I think this has the effect of grounding my cable to garage/theater ground, which would somewhat prove that this is a ground loop.

Before I ground my cable at the entrance to my garage/theater, I want to make sure I will not be causing additional problems by having my cable grounded in two places. I am concerned about adding more artifact or loops into the system. I don't think this will be a problem, but I would love the advice of an expert.

Thanks.

I had a similar problem with a basement theater powered from a sub panel. The fix ended up being the addition of a second ground from the cable directly to the ground at the sub panel. I had rather bad intermittent hum bars prior to making that connection and they were totally eliminated by the ground.

This connection was made by the cable company. The extra ground should cause no problems.

Thanks for the info I really appreciate it. That is what I thought but it is good to hear you had success with a similar problem.