Mast and LNB..seperate grounding?

[Punkitup]

Just wondering if this seems like a resonable grounding set up? The mast of the dish will have it's own ground wire run from a machine screw through the mast to it's own dedicated 8ft. ground rod.

For the LNB a seperate ground wire would acompany the RG6 Ouad Sheild Coax runs from the LNB down to a ground block on the side of the house which in turn would be grounded to the houses unified-ground system and it's 8ft. ground rod.

Now I may be missing something here but to the best of my understanding the LNB is isolated to begin with, so simply running one ground wire from the LNB would not ground the mast and help prevent potential for lighting strikes....hence the two grounds. One for the LNB and Coax Sheild. The second for the Dish supporting structure.

[boba]

Use 1 ground to the unified ground location, the LNBF is attached to the dish the dish is attached to your mast.

[apc1]

No need to ground the LNB. Run your coax drops Down to a ground block. Tie the ground block into the house ground. You can run a ground from the mast and you may use an 8' ground rod if you wish. Just make sure that the 8' ground rod is bonded back to house ground. If not you can create a ground loop which can cause problems.

[waydwolf]

Originally posted by apc1
No need to ground the LNB. Run your coax drops Down to a ground block. Tie the ground block into the house ground. You can run a ground from the mast and you may use an 8' ground rod if you wish. Just make sure that the 8' ground rod is bonded back to house ground. If not you can create a ground loop which can cause problems.

    Actually, any unnecessary grounds other than those properly installed by an electrician can create ground loops as well as other problems. Ground rods connected to the electrical ground should always be installed by a qualified licensed electrician.

    Remember, your household current runs on three lines, hot, neutral, and ground. Neutral is bonded to ground at service entry and throwing that off can lead to electrical problems with refrigerators and other motorized appliances, voltage going to the wrong place against design, electrocution, and fire.

    Leave it to a professional when it comes to electricity.

[firephoto]

All of your grounds need to be tied together electrically. If you have a separate rod for the mast you need to tie it into the existing ground system for the house. If your mast has a better earth ground than your utility ground then current could flow from the electrical service to the grounding block on the coax, through the coax to the LNB then to the mast and it's ground rod. It could also originate in the house and flow back through your receiver out the coax to the grounding block and out to the LNB again. Electricity is lazy, it goes to ground by the easiest path so you want to have all grounds at the same potential. Be sure to follow the code and use the proper wire size on your ground system too.

Good connections on your ground rods are very important too. Cadweld would be great but it might be a little too expensive for your normal around the house installation. ;)

[Punkitup]

I am the original poster...for anyone keeping track.....HaHa

First, I misspoke [typed], I should have said one ground for the LNB and it's accompanying coax runs at the ground block, not from the LNB.

As to unifing the ground rods for the mast and LNB/Coax/house that is not a problem in my case due to their close proximity to each other and I will do so. But I don't know [honestly] if there is a case to be made for a Ground Loop between the LNB/Coax/House/Electrical Coponents Beyond and that of a seperate Mast ground as they are electrically isolated by the LNB supporting arm, are they not? Unless you lived in a metal building.

But all that is beside the point, I guess my real issue is that if I do not ground the Antenna's [read: LNB] supporting structure [read: Mast & Dish-Reflector] which is electrical isolated from the former, then is there a mechanism for the build-up of potential for a lighting strike?

I have a 50ft and a 100ft tower for other forms of hobbiest electronis that I am involved with, both of which have a ground seperate from that which grounds the sheilding of their associated antenna leads. These unassociated grounds are more due to a function of mechanics and proximity then anthing else, but I would not think of putting these supporting structures in the air without a ground. By the way as a side note; I use Alpha Delta Surge Protectors on the antennas associated with these towers, they are rated for bandpass to 3ghz; to bad the don't come F-type connector equipped.

Peace - James/N8SBU

 

[firephoto]

Here are some pages to look out for some grounding information.

http://www.dbsforums.com/reviews/tech1_5.html
http://www.faqs.org/faqs/electrical-wiring/part1/section-31.html

There's lots of information out there about grounding but it's not all good or accurate.