Grounding Do's Don'ts & Why Part 1

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KF5LJW, Feb 27, 2012.

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  1. K9STH

    K9STH Ham Member QRZ Page

    Sometimes, dealing with the power company can be exasperating! Shortly after purchasing my existing house, and a couple of decades before going to work at TXU, my lights would suddenly go bright for a second and then back to normal. I checked with my across-the-alley neighbor, who's drop came off the same pole pig, and he was having the same problem. So, I telephoned Texas Power & Light (one of the operating companies of TXU). Finally, they agreed to install a recording volt-meter on the drop on the outside of my house. Of course, no bright lights during the time it was on line. So, TP&L removed the meter. Then, a couple of days later the bright lights started again. Therefore, TP&L was called again. After some conversation they agreed to install the voltmeter again.

    The serviceman who was handling the voltmeter installation knew me and knew that I had a problem. But, convincing his superiors was a different matter. Another couple of days and the lights went bright again. So, I went outside and looked at the recording voltmeter. The "hands" on the recording device were tangled way off scale. However, I didn't call TP&L but waited for the serviceman to come out again. The serviceman took one look at the voltmeter and called his dispatch on the radio.

    I came home for lunch that day and in the alley behind my house there were no less than 3 TP&L crews working. The pole pigs along my alley were wired with groups of 2 being in parallel. There wasn't a problem with the pole pig that is directly behind my house but the 2nd pole pig that is about 150 feet down the alley had acquired a half-cycle primary to secondary short. That is, 7200 volts was occasionally arcing to one of the 120 volt legs. The tangled "hands" on the voltmeter had definitely gotten the attention of the electric company.

    After that, whenever I telephoned the electric company about problems (i.e. noise, loose hardware, etc.), I had no problems convincing them of any problems. Fortunately, the squirrel chewed neutral was the only major problem that has occurred since the half-cycle short.

    Glen, K9STH
    K4AGO likes this.
  2. KF5LJW

    KF5LJW Ham Member QRZ Page

    No problem. later I will get into that.

    THX and 73 to you.
  3. KF5LJW

    KF5LJW Ham Member QRZ Page

    OK you got it. Here it is.
    Last edited: Feb 28, 2012
  4. VE3EKJ

    VE3EKJ Ham Member QRZ Page

    So in the interest of a common ground to satisfy codes, should I NOT put a ground rod beside my back yard tower, in favour of running a 60 foot ground strap to the main electrical ground at the front of the house?
  5. KF5LJW

    KF5LJW Ham Member QRZ Page

    See Part Two for your answer
  6. K8MHZ

    K8MHZ Ham Member QRZ Page

    Talking from US standards, to be legal you either have to ground the antenna system, or provide it with lightning arrestors that also require a grounding electrode. The grounding of the tower may be covered in NFPA 780 directly, but the base of the tower may be considered a grounding electrode anyway, and thus need to be bonded. So, no matter what, to be legal, you would have to bond your properly grounded system to your AC mains.

    Now, that being said, you have some options. One would be to run the conductor around the outside of your home (recommended, 60 feet is not that far). The NEC also allows for the use of metal pipe as a jumper, if it is accessible and continuous, and properly bonded to the AC main's grounding system. (Not recommended. The NEC is really not concerned much with lightning, just the safeness of the AC mains system).

    NFPA 780 has 'rules' for lightning systems, but if it is not adopted by your municipality, it's only a guide (and a debated one at that).
  7. WA9SVD

    WA9SVD Ham Member QRZ Page

    You seem to confuse the subject. ALL "grounds," for safety and even for lightning safety (lightning safety meaning not just direct hits) should be well attached to the home station electrical service ground, to ensure safety. RF grounds may or may not be the same, and through coax cable or various tuners, may not have an actual direct connection. ALL should be "grounded" to the electrical ground for the electrical service.
    There ARE many sources that go into the details; K6SHE, one of the moderators has a good starting point.
  8. KF5LJW

    KF5LJW Ham Member QRZ Page

    There is no confusion or question about it. It is clearly required, defined, and detailed to comply with all known electrical codes, including RF standards, operation, and practices. All grounding systems used (RF, Lightning, and Electrical) should be bonded together at some point to form a single Grounding Electrode System aka GES. Otherwise you risk kissing your property, equipment, operation, and LIFE GOOD BYE: "It was nice knowing you"
    Last edited: Feb 28, 2012
    WA7DAU likes this.
  9. K9KJM

    K9KJM Ham Member QRZ Page

    This is so important I feel it needs a direct answer: DO INSTALL a ground rod(s) right near the tower!
    The correct way to ground is for each item (Tower, Entrance point, Electric service, etc) to go to it's OWN ground rod(s) FIRST, Then be bonded together.
  10. VE3EKJ

    VE3EKJ Ham Member QRZ Page

    Thank you! This idea of a common ground has been confusing me. I build and repair guitar amplifiers for a living, mostly vacuum tube models. Musicians have never liked the sound of transistors, as the distortion in vacuum tubes is more pleasing to the human ear. Transistors being more linear make them a better choice to amplify sound that you have already created but they sound harsh when you first generate sound with an electric guitar.

    So to me, a common ground is precisely that, ONE common ground! One of the classic mistakes with people building tube amplifiers is to not understand you can't tie something to chassis ground wherever you want, like wiring lights in a car or truck body. You get ground loops and these can and do cause excessive hum, sometimes to the point of making the amplifier unusable.

    So rather than many chassis ground points good construction practice dictates that you have one common ground point, usually at the negative terminals of the power supply filter capacitors. In the "Glory Years" experienced engineers could and did use many chassis grounds but they understood how to do it without having heavy ripple currents imposed on the negative returns of sensitive preamp circuits.. Most of us today lack that experience and so one common ground tends to keep us out of trouble. Sometimes we use what is called "Star grounding", where we have a common ground for each section of the circuit and then each of those common points is brought back to the main ground. Still, what you DON'T do is put a common ground at every point along the path!

    Thanks to the diagram and the advice I've gleaned here I now understand the difference in this application. Overall, it still suggests a point I had made much earlier, that by having multiple ground points you are allowing earth charges to disperse and thereby discouraging full lightning strikes. I can't help but think of all those utilities grounds as forming a giant ground mat.

    Whatever, I now will be buying another ground rod for my tower and running some conductor to my main panel ground. Hopefully I will also lose a bit of noise on the 75 metre ONTARS net!

    Merci beaucoup, y'all!
    Last edited: Feb 29, 2012
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