Grounding Info & Standards: OTA/Dish/CATV/Telecom

[wear_dark]

Thanks ScaryBob,

I hadn't considered placing the grounding block indoors, but doing so would make my life easier. Can I mount the grounding block on the exposed rafters of my basement?

[ScaryBob]

That should be fine.

[wear_dark]

Cheers for the help!!

[Scarborough]

When I was a teenager our television antenna tower got struck by lightning. It melted a hole the size of a dime in the sheet metal panel on the air conditioning unit located about 3 or 4 in away from the tower. If my memory is correct, we were no longer using the antenna by that time yet a television still got fried, I'm assuming through the cable line.

[kilarney]

I have been playing around with antennas in my attic. I basically have been trying different positions in the attic by using a pipe and then pointing the antenna for whatever I can get. The feed comes from the antenna thru a 300 to 75 ohm transformer onto coax. My question is .... does the antenna have to be grounded with a connection on the pipe or to the frame of the structure? I know there is little chance of a lightning strike but will the performance be better or worse without a ground to the frame? I dont see how it has any ground if it goes thru the matching transformer. Is it important for performance?
Any info appreciated, thanks

[Jase88]

A coaxial cable system works by capturing external RF energy in the outer braid and grounding it out before it interferes with the centre conductor, which is where the desired signal is carried. Therefore, to remain effective, the outer braid must be grounded.

This is the primary reason for grounding coax--even for an interior install.

In terms of the antenna, an indoor antenna does not absolutely require grounding. Though it's a good idea for discharging static, etc. Attics are often humid & hot places...where charge can build up easily.

[roger1818]

Originally Posted by Jase88

Attics are often humid & hot places...where charge can build up easily.

Humidity will help dissipate static electricity. It is in dry air that static can build up easily. That is why static tends to be a bigger problem indoors in the winter, since when you heat air, the relative humility decreases. Grounding an attic antenna doesn't hurt though.

[Jase88]

Good point, roger1818. Though the advice still stands with regards to grounding.

[oneframe]

Living in a condo unit, there was obviously no way for me to check if the coax cable connection is properly grounded which I am assuming should be. After 3 years living with the humming in my audio speakers, I finally read thru the thread and tried the cheapest suggestion for which I already have - placing the coax cable thru the surge protector input then that output thru the splitter for the cable tv and internet. Wow. Zero hum. All these years. Lol.

The surge protector which all the other components (receiver, powered speakers, cable box, etc) where connected together with the coax cable brought them all to a central point of grounding which finally eliminated the hum.

I'm so happy. Thanks everyone who contributed their thoughts on this thread!

[greg111r]

Sorry if this is a stupid question, as I don't know much.
Everyone says to connect the ground for OTA with the main ground for the house. I understand the concept of potential difference, and that the main reason for grounding is to discharge static.
So what happens in the case of a direct lightening hit? The least path of resistance is now straight from the OTA rod into your house via the house ground. May cause fire etc.
Without the connection the path is straight to the 8' post in the ground. I guess the only issue that I don't understand is the point about differential between the OTA ground and house ground. So in case of lightening strike, the potential difference causes arching on the exterior of the home. If gas lines are not there is the issue that if someone was outside that they may get zapped? Is there anything else?

[JamesK]

The antenna ground should be as short and direct as possible. This usually means ground rods directly below the antenna, if possible. Even towers should have a ground rod. Once you've done that, you can also run a ground wire to the house ground that the electrical panel is tied to. You'll also want a grounding block. There's a drawing near the bottom here that shows what's required.

[roger1818]

JamesK is correct. The antenna and grounding block should be wired directly to a separate grounding rod and the ground wires kept as short as possible while staying outside the house. You then want to connect that grounding rod to your electrical ground to keep both the electrical ground and the antenna ground at the same potential.

[ScaryBob]

Grounding is meant to provide a path to ground before it finds a path though construction materials or equipment. The best way to do that is to provide a grounding rod outside and a direct path to the electrical ground (water pipe or grounding system) close to the entrance point. Note that towers typically require a much more substantial external ground than data cables from antennas and other sources.

[JamesK]

^^^^
Also, one thing I didn't care for in the diagram I linked to was the way they ran the ground to the breaker panel. If possible, it should go to where the ground enters the building, which should be where the breaker panel connects to it. Otherwise, a lightning hit could provide more of a surge to the breaker panel, due to the impedance of the breaker panel ground.

[rudolph_007]

Does anyone have the newly published 2012 Canadian Electrical Code? Until now, it is my understanding that most satellite companies have been using the American NEC. As in the Bell installation instructions, it specifically references sections of the American NEC.

But this link leads me to believe that our own CSA is finally developing their own rules for grounding satellite systems under the canadian electrical code.

http://www.google.ca/url?sa=t&rct=j&...lbvVCFxhAzH2DA