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Old 16-Oct-2018, 8:23 PM   #1
gossamer
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Grounding rod requirements

Hi, I've installed an antenna on my roof and was grounding it using the same terminal as the cable broadband connection. Cable guy said he didn't like that and cut my ground wire.

Does it somehow affect signal quality, put us in danger in some way, or was the guy just being a jerk?

In any case, I've also read that some places are only allowed one grounding rod per dwelling, so was hoping to get some expert advice on how I should proceed.

What's the best approach to grounding an antenna in northern NJ?
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Old 17-Oct-2018, 3:06 AM   #2
rabbit73
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Quote:
Originally Posted by gossamer View Post
Hi, I've installed an antenna on my roof and was grounding it using the same terminal as the cable broadband connection. Cable guy said he didn't like that and cut my ground wire.

Does it somehow affect signal quality, put us in danger in some way, or was the guy just being a jerk?
He might have had a right to do it or he could have been a jerk. It depends upon how you made your connection. Can you show us a photo of what you did?

Quote:
In any case, I've also read that some places are only allowed one grounding rod per dwelling, so was hoping to get some expert advice on how I should proceed.

What's the best approach to grounding an antenna in northern NJ?
The NEC code is only a suggestion. The local AHJ (Authority Having Jurisdiction), who is usually the electrical inspector, can say how it should be done. His interpretation becomes the law that is binding on you and the local electricians.

The code says that a second grounding rod may be used IF it is bonded to the house grounding rod with 6 gauge copper wire.

If the antenna is outside, the coax shield should be grounded with a grounding block that is connected to the house electrical system ground with 10 gauge copper wire for electrical safety and to reject interference. For further compliance with the electrical code (NEC), the mast should also be grounded in a similar manner to drain any buildup of static charge which will tend to discourage a strike, but the system will not survive a direct strike.



The latest device to ground multiple services is the IBTB. It has a lay-in clamp for the house grounding conductor without disconnecting the house grounding conductor even for a moment, which would be dangerous. Previously, split bolts were used to make individual grounding connections to the house grounding conductor.









The electrician on This Old House (PBS} showed how to install an IBTB.

As you can see, there are many screws to make connections by you and the cable guy.
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Last edited by rabbit73; 17-Oct-2018 at 3:31 AM.
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Old 17-Oct-2018, 6:11 PM   #3
Tower Guy
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Anyone who intentionally cuts any ground wire is a person who has put your house and TV equipment at risk. CATV companies are liable for grounding mistakes, so his fear is not imaginary. A good install tech would have told you the right way to connect both his and your ground. An excellent CATV installer would have connected it properly for you.
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Old 17-Oct-2018, 8:58 PM   #4
gossamer
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Anyone who intentionally cuts any ground wire is a person who has put your house and TV equipment at risk. CATV companies are liable for grounding mistakes, so his fear is not imaginary. A good install tech would have told you the right way to connect both his and your ground. An excellent CATV installer would have connected it properly for you.
Thanks very much. That's what I would have expected as well. He definitely had a chip on his shoulder.

Could it somehow affect my signal quality using their grounding rod, or potentially affect how ground works, or even put me at risk (assuming I did it correctly)?
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Old 17-Oct-2018, 9:16 PM   #5
Tower Guy
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Grounding does not effect TV reception unless there are extremely strong nearby transmitters, especially high power AM stations.

The key to a safe ground system is to have every ground tied together in a single location as close as possible to your main breaker panel.
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Old 17-Oct-2018, 9:54 PM   #6
gossamer
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Originally Posted by rabbit73 View Post
He might have had a right to do it or he could have been a jerk. It depends upon how you made your connection. Can you show us a photo of what you did?
It's all really been disassembled now.

Quote:
If the antenna is outside, the coax shield should be grounded with a grounding block that is connected to the house electrical system ground with 10 gauge copper wire for electrical safety and to reject interference.
That's what I was using.

Thank you for your explanation and diagram. I had used wireties to fasten the coax to the mast, so obviously I'm doing that wrong. Where can I buy the standoff described in the diagram, to extent the coax off of the mast?

Quote:
For further compliance with the electrical code (NEC), the mast should also be grounded in a similar manner to drain any buildup of static charge which will tend to discourage a strike, but the system will not survive a direct strike.
I went out to look again at the big wire mess and here's what I learned:
  • There appears to be an old Verizon telephone wire terminating in an old junction box in the house and going all the way to the pole.
  • My antenna coax cable is grounded to our main house ground at the base to a coupler around where it enters the house
  • The ground wire that was cut was my antenna mast ground wire
  • The cable company is also using the house ground with a basic coupler at the base, near where it enters the house

I'm thinking the best place would be to either use the same basic coupler as my antenna, which ultimately leads to ground, or perhaps somehow splice the existing ground and add my ground to it?

I've included an image that describes what I'm seeing. For some reason it isn't displaying it inline with the IMG tags.

https://imgur.com/UNYrReE

Thanks
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Old 22-Oct-2018, 9:41 PM   #7
rickbb
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For the mast you don't need the coupler like is used on coax, just the split bolt to clamp it to the ground wire going to the rod.

Mount it below all that other stuff, just wire to wire.
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Old 23-Oct-2018, 2:40 AM   #8
rabbit73
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Originally Posted by gossamer View Post
I've included an image that describes what I'm seeing. For some reason it isn't displaying it inline with the IMG tags.

https://imgur.com/UNYrReE

Thanks
It must have .jpg after ReE before adding BB Code for img.

like this

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Old 23-Oct-2018, 3:04 AM   #9
gossamer
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Originally Posted by rickbb View Post
For the mast you don't need the coupler like is used on coax, just the split bolt to clamp it to the ground wire going to the rod.

Mount it below all that other stuff, just wire to wire.
Can I use one of the existing split bolt, or are you suggesting I should splice the wire again for my purpose?
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Old 23-Oct-2018, 2:53 PM   #10
rabbit73
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The code says the coax shield should be grounded using the grounding block and the mast should be grounded, each with its own separate 10 gauge copper wire connected to the house ground. Don't make a splice, use a separate split bolt for each. The split bolt is an open "U" that will surround the house ground wire when the nut for the split bolt is removed.



Quote:
Thank you for your explanation and diagram. I had used wireties to fasten the coax to the mast, so obviously I'm doing that wrong. Where can I buy the standoff described in the diagram, to extent the coax off of the mast?
The diagram is a little out of date. You can fasten the coax to the mast. Many years ago 300 ohm twin lead was used instead of coax. It had to be kept away from nearby metal objects, hence the standoff insulator. Then coax came along and coax standoffs were available for it. The insulator in the standoff was designed for coax or twin lead (slot in insulator). The metal of the standoff that surrounds the feed line insulator is not closed (it's a hook), to avoid having a shorted turn around the twin lead which would affect the signals in the twin lead.

https://www.summitsource.com/Channel...071-P9727.aspx

https://www.summitsource.com/Channel...072-P9726.aspx
Attached Images
File Type: jpg Split Bolt7_1.jpg (71.4 KB, 219 views)
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Last edited by rabbit73; 23-Oct-2018 at 3:14 PM.
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Old 25-Oct-2018, 9:53 PM   #11
gossamer
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Quote:
Originally Posted by rabbit73 View Post
The code says the coax shield should be grounded using the grounding block and the mast should be grounded, each with its own separate 10 gauge copper wire connected to the house ground. Don't make a splice, use a separate split bolt for each. The split bolt is an open "U" that will surround the house ground wire when the nut for the split bolt is removed.



The diagram is a little out of date. You can fasten the coax to the mast. Many years ago 300 ohm twin lead was used instead of coax. It had to be kept away from nearby metal objects, hence the standoff insulator. Then coax came along and coax standoffs were available for it. The insulator in the standoff was designed for coax or twin lead (slot in insulator). The metal of the standoff that surrounds the feed line insulator is not closed (it's a hook), to avoid having a shorted turn around the twin lead which would affect the signals in the twin lead.
I ordered a split bolt and it's the wrong size. It's 2 str to 8 str AWG, and it's huge. Can you tell me which gauge I should purchase? Perhaps you have a specific one you recommend?

Also, just to be clear, the idea here is to strip a section of the ground wire close to the point where it leaves the house, correct? It's not possible to just add the ground wire to an existing split bolt?
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Old 25-Oct-2018, 10:26 PM   #12
Stereocraig
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If it's too large for the ground, then strip back the wire twice as far and fold it over on itself so the bolt thinks it's accommodating a heavier gauge wire.
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Old 26-Oct-2018, 6:50 PM   #13
rickbb
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If it fits well you can add it to an existing split bolt. Key is a good solid connection.
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Old 26-Oct-2018, 9:03 PM   #14
gossamer
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If it fits well you can add it to an existing split bolt. Key is a good solid connection.
Awesome, thanks. That sounds like a better solution than using the wrong sized tool for the job. Also saves money :-)
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