Ground Rods

Discussion in 'Archived Threads 2001-2004' started by David_Schiller, Nov 13, 2001.

  1. David_Schiller

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    Will ground rods help improve AC power line conditioning and possibly eliminate a subwoofer grond loop? I've been told that most people's homes are not grounded very well. How is a receptacle's ground connected to the ground rod (through a wire from the service box?)?
     
  2. Wayne A. Pflughaupt

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    David,
    Don’t know where you heard that most people’s homes are not grounded well. If local ordinances aren’t enough to insure proper electrical wiring, any electrician worth his salt will follow the standards of the National Electrical Code.
    Most homes built in the past 35-40 years have grounded service. Basically if your home has grounded electrical outlets, you generally don’t have to worry about the ground not being good. The wiring typically used in residential applications (romex) includes a wire for grounding. It attaches to the ground lug at the outlet (the round hole on the front of the outlet). At the service panel all grounds attach to a common buss, and a heavy-gauge wire goes from the buss to the ground stake.
    If your home doesn’t have grounded service, it’s really not practical to re-wire the entire house. However, an electrician could install grounded circuits at some places, depending on access to a particular location.
    If you have a ground loop and you have grounded service, usually it is because equipment is connected to two or more circuits on opposite different service legs (or phases). The other cause is often the CATV service.
    Regards,
    Wayne A. Pflughaupt
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  3. David_Schiller

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    Wayne,
    How can the CATV service cause a problem? I've heard this before, but I don't recall what the answer or solution is. I wonder if getting DirecTV (which I'm doing in Jan.) will fix the ground loop problem.
    Definitely sounds like I shouldn't pursue messing around with ground rods...
    -David
     
  4. Gary Silverman

    Gary Silverman Stunt Coordinator

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    Sometimes, when catv or satellite is installed, the installer will install a separate ground rod because it's not convenient to run the ground wire back to the electrical service grounding electrode.. This can cause ground loops and is a violation of the National Electric Code. All grounds for this equipment must be run back to the service.
     
  5. Wayne A. Pflughaupt

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    David,
    Gary hit the nail squarely on the head. To see if the CATV feed is causing the problem, disconnect it from the system. If the hum goes away, you’ve found your ground loop.
    If the CATV feed is the problem, check to see where it comes into the house. There should be a grounding block. It looks like a regular RF splitter, but a wire comes off it and goes to the ground stake. If there is not a grounding block, or if the wire is missing, call your cable company and have them come do the job right.
    If you get a DBS system, it will also have to ground the antenna feed to the ground stake to avoid a ground loop—just like with the CATV.
    Regards,
    Wayne A. Pflughaupt
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  6. Kevin C Brown

    Kevin C Brown Producer

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    There can be problems with a house's inherent grounding, even if it was originally installed "up to code".
    One problem? If the ground is sunk into the earth where it doesn't see a lot of water, you can't get much electrical conduction and the ground "quality" is poor.
    Check this article out, it tells you how to install a new ground correctly, and then how tie your house ground to the new ground...
    http://www.equitech.com/support/techgrnd.html
    Some other cool stuff on their site too about AC grounding.
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  7. SamRoza

    SamRoza Stunt Coordinator

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    Ground loops caused by Cable service are rather easy to handle. Here is a link to a prior discussion http://www.hometheaterforum.com/uub/...ML/044485.html
    It solved the problem for David just fine, and as long as it's a cable problem, and not an electrical problem, it will clear up your ground loop.
    No sense wasting any more time or money(some ground loop isolators that do the SAME thing cost as much as $200!) on the problem.
    Sam
     
  8. Gary Silverman

    Gary Silverman Stunt Coordinator

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    Some homes don't have a ground rod. They used the metal piping for the water service as a grounding electrode.
    In my neighborhood, the city water department came through years ago and installed new water service to all the homes. They replaced the old metal piping with new PVC pipe, thus eliminating all the grounds to all the homes in the area.They apparently didn't realize that they were cutting off eveybodys ground.
    So, check your system or have an electrician check it, to make sure you a GOOD ground.
     
  9. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    Kevin is correct. Either check yourself or have an electrician check for good ground. Example: my hous was built in 1992, but when I checked the ground, I found the ground rod clamp was loose. Also, when I grabbed the ground rod, I could actually move it a bit. I used to work for a major electrical supply company and can tell you that in our rocky soil, sometimes a shortcut has been taken in that an installer would cut a ground rod in half (normally they're 8' long) in order to make it easier/quicker to pound it into the ground. Most electricians are ethical, but this has happened. Good link too.

    Gary: good point. If you have an older home, chances are that your city has replaced metal with PVC water/wastewater service. Check to verify that a ground rod has been installed.
     

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