1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice

Grounding

Discussion in 'General Ham Radio Discussion' started by W1MSG, Sep 5, 2010.

  1. W1MSG

    W1MSG Now W1MSG

    Joined:
    May 9, 2010
    Messages:
    499
    Likes Received:
    18
    Ok I have started setting up a new grounding system for the station.

    I just drove a 8' ground rod into the ground, I only managed to get about 6' down before I hit good old new england rock, which really surprized me that I could get that deep.

    Now I am looking at buying one of the copper bar kits, I will be able to reach the bar with about 6' of 1" braided and tinned strap from inside the shack.

    I plan to ground my antenna mast, rig/tuner, and the coax to the bar and the bar to the rod with a solid copper strap.

    The coax will be grounded using these neat little straps that wrap around the coax after removing the outer insulation. Not sure if the coax ground is a good idea or if its needed so I am looking for comments on this.



    So does this make sense ??
     

  2. W5LZ

    W5LZ Crotchety Old Bastard

    Joined:
    Apr 8, 2005
    Messages:
    6,832
    Likes Received:
    771
    Craig,
    Ground -rods- just don't do as much grounding as you would think they do. Adequate safety grounding, just like RF grounding to some extent means lots of metal in contact with lots of dirt. That's so current can be passed to that dirt which isn't always that conductive. So having a 'lot' of dirt in contact with the rod to pass that current into is very nice. Six or so feet of dirt just doesn't amount to a lot of dirt (9 sqr. feet?) to absorb much current. 90 sqr. feet would absorb a lot more current than 9 sqr. feet.
    'Deep' doesn't mean as much as 'wider' for a couple of reasons. One of those reasons is that unless you live on very unusual 'dirt', deeper typically means dryer, which means less conductivity to electricity/current. So a greater number of shorter ground rods would mean more conductivity than just a few longer rods. Since you would have to connect all those rods, carry it just a step further and just bury the connecting wire, forget the rods altogether. Burying a wire/cable a couple of inches is going to be less "iffy" and easier than pounding in all them ground rods (not to mention cheaper). You end up with a radial instead of a rod. Don't have a lot of room to plant radials? Nothing says they gotta be straight, so 'wiggle'em a little.
    There really is a reason that radials work better than rods...
    - 'Doc
     
    1 person likes this.
  3. hookedon6

    hookedon6 W9WDX Amateur Radio Club Member

    Joined:
    Jun 21, 2008
    Messages:
    1,483
    Likes Received:
    236
    also don't forget that the NEC requires ALL grounds to be connected at a COMMON point.

    the method you described does NOT do that,...... if you ever have a fire , ect. you had better hope your insurance company doesn't find out (they WILL when the claims investigator shows up) :oops:
     
  4. Hutch

    Hutch Active Member

    Joined:
    Jan 26, 2009
    Messages:
    168
    Likes Received:
    3
    All good points and all easy to deal with, go to Erico or Harger web sites and you can download engineering data on grounding. These are the people that supply grounding gear to the telecoms lots of good info that can be used and scaled down.

    You should have more that a single ground rod I'd use a minimum of three in a triangular configuration (connected together). It also depends a lot on ground conductivity (usually you can find generalizations for your area on line). You can increase conductivity too, dig a hole a couple of feet deep drive your ground rods in then put rock salt in and fill the rest with gravel. periodically you can put salt on top of the gravel and water in through the gravel.

    You should find your electrical service ground and tie that into your ground system as well.

    That would give you a basic common point grounding system. From there you can add to as time and money allow. Such as ground rods and grounding cable around the entire property, if you have a chain link fence that can be tied in too.

    As for ground the cable shield, just use the lightening arrestors such as the ones from Alpha Delta, that will tie your coax into your ground system.
     
  5. W1MSG

    W1MSG Now W1MSG

    Joined:
    May 9, 2010
    Messages:
    499
    Likes Received:
    18
    Ok now I am confused, isnt the Copper Bar the common point and that bar connected to the Grounding rod.

    I am going to install radials off the grounding rod, well if that makes sense, I dont have alot of room for the radials but I can probably get 6 10' stretches run off the base of the rod like a fan, they wont go all the way around but say 3 to 6 o clock positions.
     
  6. mackmobile43

    mackmobile43 Jock Supporter

    Joined:
    Feb 11, 2008
    Messages:
    6,709
    Likes Received:
    381
    I believe he's lumping in all you homes grounds also which is silly since they all are connected to the same earth.

    The coax shield imho should not be connected to the homes path to earth in case there is a bad connection of the homes path to earth and is coupled to the shielded portion of the coax thus making the homes path to earth search of a different path to earth with a possible lightning stick being passed through that.
     
  7. Robb

    Robb Yup

    Joined:
    Dec 18, 2008
    Messages:
    11,067
    Likes Received:
    2,759
    ...Or an extension of the home ground.
    Where the power service comes into a home, there is a ground rod below that point (or there should be - to be to code). Then, a ground rod outside your shack. Between those points - another ground rod. Then as Doc said, a buried wire between these points to connect them all and create a better ground that works for RF. That is the way that I've learned to understand it - at this point...
     
  8. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    15,475
    Likes Received:
    7,540

    It's the same earth but not the same voltage potential during a strike. ALL grounds should be tied to the electrical service ground to make a single common point ground so that no two ground locations can possibly have a voltage difference between them in the event of a strike. The earth surrounding a ground rod will no longer be at zero volts during a strike for several milliseconds which is long enough to fry equipment. If all grounds are held at the same potential,whatever that is at the time, then current cannot flow from one ground location to another as it can when you do not have all grounds tied together. Don't think of ground being at zero volts all the time. It most definitely is not during a lightning strike.
     
  9. mackmobile43

    mackmobile43 Jock Supporter

    Joined:
    Feb 11, 2008
    Messages:
    6,709
    Likes Received:
    381
    The chassis of the equipment is one thing but the antenna and it's components should be grounded separately, right?
     
  10. Robb

    Robb Yup

    Joined:
    Dec 18, 2008
    Messages:
    11,067
    Likes Received:
    2,759
    That would be connected to the RF ground - which is a part of the entire ground/link. But this also depends on the kind of antenna we are talking about - right? You aren't going to run an RF ground for a wire dipole; but even that needs to have a well-established ground 'radial' between the ground points. All antennas work off of the earth. So establishing a solid ground system still creates a reference point. Hopefully better than no/poor ground at all...
    :whistle:
     
  11. mackmobile43

    mackmobile43 Jock Supporter

    Joined:
    Feb 11, 2008
    Messages:
    6,709
    Likes Received:
    381
    Yes but even a dipole uses the shield of the coax as a path to earth so what's your point?:whistle:

    Point is static(lightning)needs a path to earth and that's why it chooses your dipole also.

    The ground side of the dipole is the radiators counterpoise(artificial earth) so the coaxes shield does not act as an rf transformer to earth.
     
  12. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    15,475
    Likes Received:
    7,540
    Nope. ALL grounding points should be tied together at one common point. Remember that if the antenna and it's components are grounded separately then that still leaves the potential for a difference in voltage drop between the antenna and the equipment chassis and since the two are connected via the coax cable or even the third wire in the AC cord depending if it is tied to the common point or not, current will flow on the shield of the coax back into the shack.

    I see the new owners of Polyphaser pulled all their online info regarding grounding. Good thing I downloaded it before they pulled it. Hopefully it comes out here as a .pdf attachment.
     

    Attached Files:

    #12 Captain Kilowatt, Sep 5, 2010
    Last edited: Sep 5, 2010
  13. mackmobile43

    mackmobile43 Jock Supporter

    Joined:
    Feb 11, 2008
    Messages:
    6,709
    Likes Received:
    381
    I suppose I should have said the antenna will have an extra ground and not separate grounds because when a storm approaches I disconnect my coax from the rig at that point it would not be grounded if not for the extra set of ground straps that I use from the antenna mast/tower and coax shield before it enters the shack.
     
  14. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    15,475
    Likes Received:
    7,540
    Well, yeah if you disconnect the antenna completely then all is good. Check out my post above as I added a Polyphaser info attachment about grounding.
     
  15. mackmobile43

    mackmobile43 Jock Supporter

    Joined:
    Feb 11, 2008
    Messages:
    6,709
    Likes Received:
    381
    tenfew
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!