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Author Topic: Bonding grounds questions  (Read 1048 times)
KD5NDQ
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Posts: 33




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« on: February 25, 2019, 04:39:31 PM »

I have a ground rod next to where my feedlines come into the basement shack that I intend to ground feedlines to. The rod is leftover from when previous homeowners had satellite TV and the coax from roof was attached to it. It is not bonded to the electrical service ground, and these rods are on opposite long sides of house.  Sad I intend to run #6 solid copper from this ground rod to the one at the electrical service entrance.

1) The distance between the 2 rods is 131' and has to traverse a concrete sidewalk and patio next to the house where the service ground is located. I could get it to the service ground if I attach the last 5' or so to the house and then not have to break up any concrete. Is this acceptable? Also, can I use a 100' roll of wire then another (third) ground rod to attach the remaining 30'some feet, and can I bury where the 2 copper lengths meet at this rod?

2) There is a copper piped cold water faucet coming out of the basement much closer than the service ground. Would this be an acceptable substitute to connect to instead if I can verify the pipes are grounded with the service ground? If so, how do I verify this?

3) (Biggee and afraid to ask) How do I verify in this 40 year old house the service ground is actually "ground" the way it is supposed to be? Can I verify this and #2 above with a VOM?

There is no residential building code where I live although the county has recently adopted commercial building codes.

73's
Bob
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K0ZN
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Posts: 1862




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« Reply #1 on: February 25, 2019, 07:05:17 PM »

For full disclosure, I am not an electrician. I have been exposed to a lot of grounding issues over the years and some work related issues. That said, I highly suspect you will get somebody with professional qualifications to comment. You asked quite a few questions; a couple of things jump out at me.
1.) If you are wanting lightning protection at your initial feedline ground, you want at least 3 ground rods (more is even better), typically separated by 8 to 10 feet. and bonded together with a heavy conductor. One ground rod is more of a "static drain" than a real lightning ground SYSTEM. Remember, you are trying to dissipate many thousands of amperes!
2.) If you have to run 131 ft, I would go to #4 even if #6 meets code.  
3.) I would bet a sizeable amount of money that the 40 year old original residential ground rod is literally gone/rusted out. A new rod is in order.
4.) You can't measure ground resistance with a multimeter.  Yes, ground resistance can be measured with a special type of meter...It is likely the power company should/would come out and check and/or replace it. It is to their benefit as well as yours that you have a good service ground. I would just call them and flat ASK for a new ground rod, explaining that the current one is 40 years old and "to your knowledge" is rusted away and not effective. While they are out, I would ask them to tighten any mechanical connections on your drop, ground connections at the transformer, etc. Second choice is to get a licensed electrician who has the equipment....but if you replace the rod, those questions go away.
5.) Can't tell you for sure what code is on the water pipe. I can tell you that in many homes I have seen, including mine, have both a ground rod ground and a copper water pipe ground (connected right where the pipe comes through the foundation into the house. i.e. before the water meter.) Both of those are bonded together in the panel box.
6.) You should be able to attach the wire to the house; I'm sure code is that it would need to be protected in some type of conduit.
7.)  Can't see a problem with your 3rd ground rod. Again, burial probably requires some type of conduit to protect the wire.
The biggest problem you have is the cost of 131 ft. of AWG #4 Solid copper wire !!

FYI:  If you live in a high lightning area, the efforts to provide a GOOD ground to your feedlines BEFORE they enter the house are time and money well spent. You want any lightning hit to go to ground BEFORE the cables come into the house.

73,  K0ZN
« Last Edit: February 25, 2019, 07:13:43 PM by K0ZN » Logged
W2BLC
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Posts: 40




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« Reply #2 on: February 26, 2019, 03:22:12 AM »

Similar situation here:

30 years ago I had a roll of #2 copper and ran it between the far corner of the house to the power entry point. I have three rods at the shack and added a new rod at the power entry. An additional rod was added a few years ago when a large Generac system was installed (also bonded to the main #2 line). Everything is connected (brazing is suggested, but few go to the trouble). The connectors used by the power companies are excellent if you can get them. They are much stronger and have more surface than what you will find at a hardware store.
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W9IQ
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Posts: 3524




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« Reply #3 on: February 26, 2019, 03:44:00 AM »

If you wish to have the most electrically and mechanically reliable method of attaching ground wires to ground rods, use an exothermic, self contained welding product such as that produced by Cadweld. No clamps or connectors are required and the connections can be buried.

The latest issue of QST has an article on this method of bonding. There are also several YouTube videos that show the process. In less than 30 minutes and for less than $20, you have a permanent, worry free connection.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
WA7AQH
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Posts: 0




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« Reply #4 on: March 04, 2019, 04:32:01 PM »

Not an electrician either, but would add only one thing to the previous comments. With 131' run between ground rods, you've got a pretty good RF antenna there. Generally, on long wire runs you want to ground it every 16' or so to keep it from radiating.
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N4NYY
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Posts: 5224




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« Reply #5 on: March 04, 2019, 04:47:47 PM »

I have a ground rod next to where my feedlines come into the basement shack that I intend to ground feedlines to. The rod is leftover from when previous homeowners had satellite TV and the coax from roof was attached to it. It is not bonded to the electrical service ground, and these rods are on opposite long sides of house.  Sad I intend to run #6 solid copper from this ground rod to the one at the electrical service entrance.



73's
Bob

I have a single point entry panel that is grounded to its own grounding rod, and that is bonded to the electric service panel rod via 4 gauge solid copper. All ground rods that you have, should be bonded this way. The feedlines are attached and bonded to the panel via sheet metal copper, with Alpha-Delta gas adapter/barrel connectors. I also use an antenna switch to ground the center conductor, to the coax shield, thus creating a dead short between the entry panel and the center conductor.

As I have understood it, having your lines grounded inside the house, invites lightning inside, which then can spread or jump to your Romex and start a major fire. The idea is to keep lightning outside the house, even in the event of a direct hit.

You need an electrician familiar with national code to add to and correct what I have said.

« Last Edit: March 04, 2019, 04:50:12 PM by N4NYY » Logged
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