Electrical Question

[ROANIN]

I have a garage that is fed with a 3 wire feed from one pole transformer and my house is same from a different pole transformer. Both locations have a ground rod attached to the box. The cable TV is connected to both sites using a splitter. ( This was installed by the cable company before I bought the house) Is this a possible ground problem? The cable eventually connects the shield to the ground of each television in both locations. Saw a similar post the other day that got me thinking.....

Roanin

[Existential Angst]

Anything can happen with ground/hum, but methinks the solution is dirt-simple, if there is a problem: Connect both ground rods with a wire. Proly not a bad idea even if there isn't a problem, if one ground is superior to the other, which can easily be the case. Codes notwithstanding, of course.

[jamesgangnc]

You probably have a ground loop. Do you have a hum problem at any of the tv locations? If not then I would not worry about it. If you do then the correct solution is to get an isolator for one location. The quick and dirty solution is to lift the ground at one location.

Ground loops often have a small differential voltage typically present as 60 cycles. It's not dangerous but often gets into audio circuitry which is designed to amplify anything between 20hz and 20khz.

Adding more ground connections seldom helps as they all must travel some distance and that's the reason you have a problem.

[gfretwell]

EA has the right answer, bond the ground electrode systems together.

When I was in the computer business we fixed a lot of problems this way when networks spanned several buildings. A lightning strike will resolve this ground shift through your TV if you don't.

[jamesgangnc]

That won't fix ground loop hum in audio.

[Existential Angst]

Do I get a prize???

[Tony]

Like was posted, if you have a hum you probably have a ground loop, if not hum, don't worry about it. I worked on a friends entertainment center for hours before finding that if, and only if the center bass speaker for surround sound and the cable tv was hooked up, he would get a real bad hum. I forget how I fixed it?

[ROANIN]

OK thanks for the replies. I have no problems right at the moment, was just wanting to make sure it was safe. The ground rods are about 200 feet apart FYI.

[gfretwell]

Did the OP say he had an audio hum problem? I missed that part.

[JIMMIE]

Stuff happens and this arrangement may makes stuff somewhat more likely to happen.

A house may last your lifetime and never need the ground connection that was provided for it. What happens if one day that ground is called upon to do its duty and the only path it has is through your TV set, cable box cable modem and various other equipment out in the garage. For audio there are isolation transformers commercially available made to handle the situation you describe. I dont know if there is anything available to isolate a cable TV signal commercially.Perhaps googling TV isolation transformer may return something.

Jimmie