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End fed wire from attic to outdoors?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KO4OCF, Jun 11, 2021.

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  1. AK5B

    AK5B Ham Member QRZ Page

    I will also attempt to simplify the ideal station earthing scenario (as one who was also confused for a long time by the deluge of information on the subject until fairly recently).

    A few months ago, I happened across a simple diagram showing the difference between a station bonded to a Single Point Ground and the same station bonded to a ground rod outside the shack and via the third wire in the AC (mains) outlet and DC power supply which, by doing so, created a dangerous Ground Loop.

    The diagram made sense to me and finally, everything was crystal clear to me. It was posted by Derek, KF5LJW, in a long thread on the subject of grounding and I will see if I can locate it to re-post here once I do.

    In the meantime, here is my attempt at simplifying the ideal and proper way to earth one's station:

    1) All coax, feedlines, control lines,antenna discharge units (ADU), wires and cabling for telephone, satellite, internet, TV, etc. should all be bonded to the AC (mains) service panel Ground Electrode and enter the house at or as close as possible to this same rod which, by this use as outlined is the ideal Single Point Ground.

    1a: If the ham shack is located far from this Single Point Ground entry point, the cabling should still enter near it and can then be routed through the attic or other interior space to reach the operating position---any other routing that bypasses the SPG/entry panel creates potential ground loops.

    2) Metal masts, tower legs and their corresponding antenna feedlines should be bonded to ground rods beneath them and those rods should be bonded together by a #6 AWG or heavier copper wire going all the way back to the Single Point Ground at the house entry panel (additional rods can also be installed (at least 16 feet apart) along the way for the best possible lightning surge protection).

    If anything I've just written is incorrect, Bob, N0TZU or some other knowledgeable grounding guru will (please) correct me without delay. I am by no means any sort of expert on the subject---and grounding safety is certainly nothing to sneeze at or risk by attempting some sort of "home-brew shortcuts." It's just that once I understood the basic principles of static discharge and lightning-induced surges I felt a lot more comfortable about delving into the subject, especially for the benefit of my own lightning safety and proper earthing for my new QTH.

    73,

    Jeff
     
    N0TZU likes this.
  2. G0KDT

    G0KDT Ham Member QRZ Page

    See the post I'd just made as you posted your reply.

    Frankly I have had it with employing people to work on my place. They know no better, when I tried to get an aerial rigger to do the tv they botched that and broke slates.. cost more to repair their damage so as to the idea of getting a rigger for amateur radio kit ... that is total non starter here in the UK.
     
  3. G0KDT

    G0KDT Ham Member QRZ Page

    Jeff,

    Nice summary of your findings and understanding. I've seen similar but when there is only 1 rusty earth stake from possibly when the house was built in 1935 and its a long way from any shack or coax entry point it gets tricky. Running 6mm wire from loft or dimetrically the opposite corner of the building at ground floor level is also not easily done without digging up a lot of patio and driveway.

    Over here, I've never seen the tv antenna pole or coax grounded except via the tv aerial socket in 60yrs+

    I elected to use two aluminium poles joined standing on the ground and bracketed to the house wall at about 2.5m spacing to give about 6m of height at the house. With enough coax attached its couple u bolts and I can lower the lot. The only fiddly bit will be the counterpoise for an EFHW and getting that released to come down easily. I am working on an idea for that as yet undecided.
     
    AK5B likes this.
  4. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    Good summary!

    I would add that though a literal single point ground is ideal, if it isn’t practical to run the feed line cable inside from the AC service entrance to the radio room, then it can enter elsewhere and the ADU bonded back to the AC service, but with less protection from surges as the distance increases because of the inductance of the bonding wire. (The code isn’t as clear as it could be for amateur installations but telecom is allowed up to 20 feet. Beyond that supplemental rods are required at least every 20 feet. I would do 16 feet).

    Thanks for the compliment, but I consider myself a student of grounding, not a “guru”.
     
    Last edited: Jun 13, 2021
    WA7ARK and AK5B like this.
  5. AK5B

    AK5B Ham Member QRZ Page

    Thanks Bob, for both the compliment as well as the explanation of the more distant entry point alternative to the ideal.
    I'm still going ahead with my "ideal" plan and re-locating my shack from a back bedroom all the way into a corner of our living room as the service panel is just outside---but it's good to know it could be different if I was willing to give up a portion of protection in any case.

    Guru or not, you are one well-grounded student!

    73,

    Jeff
     
    N0TZU likes this.
  6. AK5B

    AK5B Ham Member QRZ Page

    I think it boils down to this undeniable fact: Good grounding for static and lightning protection is seldom convenient nor thrifty.

    At least you chaps in the UK don't suffer through nearly as many lightning events like we do on this more southerly side of the pond.

    GL and 73,

    Jeff
     
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  7. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    According to Vaisala’s global lightning network, the US on average has 18 flashes/km/yr compared to the UK at 0.6, a ratio of 30 times. But the US is very large, and it ranges from near zero on the west coast to 70 or more in parts of the Gulf Coast and Florida.
     
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  8. KO4OCF

    KO4OCF Ham Member QRZ Page

    I am not missing the point about grounding. I acknowledged the need for grounding in an earlier post. Please close this thread.
     
  9. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    Ok, it is of course up to you. Have fun and good DX!
     
  10. WA7ARK

    WA7ARK Ham Member QRZ Page

    Threads have a life of their own long after the OP fades away....

    I find Dereck's idealized SPG to be non-practical for most hams. At six out of the eight houses I have lived in, the natural place for the coax to enter the house wall to get to where the ham rig is has always been about as far away from the meter base as possible. So I always had to run a bonding wire around the outside of the house, which means ground rod(s) under the tower, ground rod where the coax enters the house wall, and bonding wires between the tower and entry point, and entry point to meter base.

    This creates a "ground loop" between the ham rig and meter base (one path through the house wiring, the other through the bonding wire). So What? If lightning strikes, the current divides inversely proportional to the impedance (from DC to ~1MHz) in the two parallel paths between the entry ground rod and the meter base ground. The #6 awg bonding wire takes most of the current compared to the #14 inside the house...
     
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