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Grounding- what issues does it solve?

Discussion in 'DIRECTV Installation/MDU Discussion' started by liquidctv, Jan 12, 2011.

  1. liquidctv

    liquidctv Legend

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    Oct 13, 2010
    We all know that we are supposed to ground our dishes. And it's a good feeling, knowing that excess current is draining away into the earth.

    But on a practical level, what signal issues have you seen resolved, by proper grounding?
     
  2. epifano83

    epifano83 Mentor

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    I've seen pixel issues being one
     
  3. liquidctv

    liquidctv Legend

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    Oct 13, 2010
    Yeah, and can you say what signal meters predicted this pixelization?

    Zeroes on swm channels, or zeroes on satellite transponders?
     
  4. dsw2112

    dsw2112 Always Searching

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    On a basic level grounding a coaxial cable is designed to shunt external interference to ground. There will be several different answers as to the "why" in this thread, but if you've ever played with RF this is a cardinal rule to follow.
     
  5. liquidctv

    liquidctv Legend

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    >if you've ever played with RF this is a cardinal rule to follow.

    Well, there are an awful lot of dishes that work fine without grounding. Especially 6x8's installed on the roof.

    But I am concerned about bigger swm installs.
     
  6. dsw2112

    dsw2112 Always Searching

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    Then why ask the question? You can generalize anything...just answering the question you asked, and as someone with an RF background I happen to know a "bit" about it. There's a reason there's shielding on a coax cable, and to answer directly there's countless "issues" grounding will remedy (especially on a bigger SWM install.)
     
  7. P Smith

    P Smith Mr. FixAnything

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    you mean connect shield to device's analog ground, right ? that would be different requirement from grounding to Earth:
    - to drain static electricity induced by environment outside of your dwelling
    - to prevent electrical damaging devices or/and electroshock of living organisms in case of touching that part what lost neutral line
     
  8. dsw2112

    dsw2112 Always Searching

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    No. I meant an earth ground. Most devices do not have a three prong plug, thus no true earth ground.
     
  9. P Smith

    P Smith Mr. FixAnything

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    then from RF stand point it would be a mistake - coax cable's shield isn't suppose to use for cover connection to Earth to fulfill mentioned two reasons above
    the shield must have one connection - to RF input of that receiving device, then it will work as mandated for RF circuits: to keep impedance and protect from EMI
     
  10. Bnottt

    Bnottt Cool Member

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    Jan 4, 2011
    Grounding is not about correction. It's about prevention. Like a rubber. Many excuses on why not used. Also many horror stories on when not used........ Think about it.
     
  11. codespy

    codespy Ted- Get some free agents NOW!!! DBSTalk Club

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    From a practical electrical theory standpoint, 2 issues off the top of my head:

    - House and Dish located near transmission lines/overhead service drop.

    - Dish located near items likely to be energized or possibly energized.

    A third reason (not related to normal conditions) would be surges....static discharge from a nearby lightning strike.

    Lightning looks for the fastest way to ground...low impedence ground path. Without the ground wire on your antenna, it will follow the shielding into your satellite distribution equipment, nuke everything in its path, etc.

    Although many feel Article 800 of the NEC is a joke, there is a good reason it is there.
     
  12. dsw2112

    dsw2112 Always Searching

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    :confused: What is the mistake? It's basic electronic theory -- coaxial shielding needs a path to ground to shunt outside RF interference. A receiver (device) without a third prong cannot provide such a path for the shielding. If you believe that a setup with two prong receivers and no ground block (tied to earth) will cover the below reasons you are incorrect:

    Where would the static electricy have to shunt to with no ground block and a two prong receiver? In any case the coaxial shielding is not there as a safety ground should the receiver casing become electrified. Technically it would work as such, but a ground plug on the receiver would be a much better option.

    Your posts are confusing so I'm not entirely sure what you're saying, but I wanted to clear up the above.
     
  13. Bnottt

    Bnottt Cool Member

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    Jan 4, 2011
    Ok. But honestly. What good tech won't ground. Every time. When possible.......? We all know that it's not always possible. But who wouldn't ground when possible and then after that call themselves a good tech? I bet you their system is grounded. Corners seem to only get cut when we are look for ways to get home faster, not when we are talking about our own systems. A lot of bad customer service is what I see. But that's just me.
     
  14. codespy

    codespy Ted- Get some free agents NOW!!! DBSTalk Club

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    Techs usually will ground MS's, not Antennas (my experience).

    When I got WHDVR late last spring with 11 IRD's, DirecTV alotted 30 minutes for the install. What a joke that was....not a lot of extra time. 4 hours later after a bad SWiM-16 port, and the techs near me get pay deducted for going over the alotted time of the install.

    It will get easier in the future for the installers on newer homes. For the 2008 NEC, the code requires an intersystem bonding block to provide at least 3 connections for grounding of different systems. (Phone, Sat, CATV, etc.). It is to be located at the service equipment (either inside or outside). This will make it easier to ground Sat equipment. And with the changes in Article 250 for grounding to rebar in footing/foundation, many structures may not have ground rods at all when they get built in the future.

    Techs, as far as I can see, are some of the worst paid people in the world for what they have to deal with. As I am a product of the construction trades, this is my observation.
     
  15. Bnottt

    Bnottt Cool Member

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    Yeah I'm with you but codespy. It doesnt take 30 mins to ground. Even correctly. It only takes a sec. I mean really. A good tech. The ones you are talking about are good because they are. And grounding is part of that good that will get the money that is missing. The so called little stuff.
     
  16. codespy

    codespy Ted- Get some free agents NOW!!! DBSTalk Club

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    Sure it may take a sec...unifinished basement, copper water pipes, and an exposed grounding electrode conductor going to the rod electrodes....that's a perfect world.

    Now install a new dish antenna on the second story, no access to grounding electrode conductors, finished (drywall) basement, PEX (plastic) water piping, etc., and the customer doesn't want to see wires running down the side of the house to grade.

    With soil conditions near my area all rock, try pounding an 8' ground rod in, then take winter frost into consideration if there are soils.

    No two installs are exactly alike, and there are many, many variables which people don't even realize.

    These guys got it rough around here by me. Which is why I help out and tip well.
     
  17. joe diamond

    joe diamond Hall Of Fame

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    "Yes...thank you for your information Mr. Installer...but that dish goes around back and out of sight..............do not confuse me with your details.....I am a stock holder and will call your boss if I do not see my game this weekend."

    Hello.....Hello!....Where are you?....Did he leave?......


    Joe
     
  18. bobcamp1

    bobcamp1 Icon

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    This is a misconception. That type of grounding won't protect against lightning damage. It will actually encourage a strike. Only a properly-installed lightning rod protects against lightning strikes. Even that is controversial.
     
  19. Shades228

    Shades228 DaBears

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  20. P Smith

    P Smith Mr. FixAnything

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