Bonding antenna and coaxial cable.

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ritelec

ritelec

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Jersey
I have a panel in the basement. One gec goes from neutral to ground rod at panel (under panel in basement floor). Another gec goes from neutral to water pipe then ground rod in basement.

I will be installing a antenna. Should I install another rod on the "exterior" of the building, connect it to the neutral with #6, then run #10 to antenna and #10 to (the coaxial) Antenna discharge unit?

OR can I install a IBT from the basement to the exterior and bring the bonds to it?

I'm reading the Antenna discharge unit can be bonded inside or outside the building, but I'm concerned about bonding it inside the building... which I would be doing if I bonded to the intersystem bonding terminal.

True if I put a rod outside, it would still get bonded inside, but I would think any strike would go to earth outside then, rather than back indoors ??

Thank you
 
sorry.
Also, can one # 10 go up to the antenna. And ground the antenna and coaxial ground up high, so I can enter the house on the second floor and save some length on coaxial? (not cause I'm cheap but for picture quality)
Or does that cable need to be bonded down by earth??

Thanks
 
I recommend you re-read the applicable sections of the NEC for antenna masts and also refer to NFPA 780.

The interior/exterior question may depend on how much flashover you are willing to risk.
 
You don't need an ADU for your installation.

You do need to ground/bond the shield of the coax just before it enters the building using something like this:

grounding_gb1_hf_big.jpg



Ideally, there would be a ground rod close to the connector. The ground rod would be bonded to the mains grounding system, outside the building if at all possible.

If you do decide to use an ADU, it would be installed just like the bonding bar pictured.
 
K8MHZ said:
You don't need an ADU for your installation.

You do need to ground/bond the shield of the coax just before it enters the building using something like this:

grounding_gb1_hf_big.jpg



Ideally, there would be a ground rod close to the connector. The ground rod would be bonded to the mains grounding system, outside the building if at all possible.

If you do decide to use an ADU, it would be installed just like the bonding bar pictured.
Click to expand...
Does that bonding device also contain an engineered air gap in the insulation inside the barrel?
 
GoldDigger said:
Does that bonding device also contain an engineered air gap in the insulation inside the barrel?
Click to expand...

Not to be a smart aleck, but...yeah...about a 50 Ohm impedance "engineered" impedance, thought not an air gap.


I mean, seriously:eek:hmy:, with regard to my previous comment...If you don't recognize that device pictured, then I seriously doubt you have perused 70 or 780 WRT bonding for lightning protective devices or antenna system bonding.
 
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cuba_pete said:
Not to be a smart aleck, but...yeah...about a 50 Ohm impedance "engineered" impedance, thought not an air gap.


I mean, seriously:eek:hmy:, with regard to my previous comment...If you don't recognize that device pictured, then I seriously doubt you have perused 70 or 780 WRT bonding for lightning protective devices or antenna system bonding.
Click to expand...

Actually, the one pictured is probably 75 ohms to match the impedance of the cable commonly used in television.
 
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K8MHZ said:
You don't need an ADU for your installation.

You do need to ground/bond the shield of the coax just before it enters the building using something like this:

grounding_gb1_hf_big.jpg



Ideally, there would be a ground rod close to the connector. The ground rod would be bonded to the mains grounding system, outside the building if at all possible.

If you do decide to use an ADU, it would be installed just like the bonding bar pictured.
Click to expand...

That's part of my original question.

BOTH Ground rods are in the basement.
Would it be best to drive another one outside and attach to it ( and yes that rod would also go back to the panel ( or other rod )!

In reading from what I get of it both antenna and coax ground just need to go to the inter system bonding terminal.
 
ritelec said:
That's part of my original question.

BOTH Ground rods are in the basement.
Would it be best to drive another one outside and attach to it ( and yes that rod would also go back to the panel ( or other rod )!

In reading from what I get of it both antenna and coax ground just need to go to the inter system bonding terminal.
Click to expand...

Yes, the connections can be made at the intersystem bonding terminal.

I don't really like the idea of grounding rods inside the basement.

I wouldn't bother driving another rod just for the TV antenna, but it wouldn't hurt, either.
 
K8MHZ said:
Someone familiar with radio systems should know that 30 ohms is the best for power transmission and 75 ohms is the best for receiving sensitivity. 50 ohms is in the middle and is used on systems that both transmit and receive, like ham and CB radio.
Click to expand...

On further examination of your photo...I would say that someone who is installing an antenna mast and relies on a General Electrical Forum of unknown entities for advice...and ends up with a FVCH 3 GHz satellite TV coaxial grounding block for an installation such as this...;)
 
cuba_pete said:
On further examination of your photo...I would say that someone who is installing an antenna mast and relies on a General Electrical Forum of unknown entities for advice...and ends up with a FVCH 3 GHz satellite TV coaxial grounding block for an installation such as this...;)
Click to expand...

Yes. When you are unsure about something you should just go ahead and wire away.

Instead of going to a forum to discuss things.

Like grounding an antenna as running as straight a run as possible , but there's a large soffit so there will be no "straight" run to the earth. Now what. As possible ???

Suggestion for an inexperienced antenna grounder ?

If you can please try to reply with no sarcasm. If you can.
 
cuba_pete said:
On further examination of your photo...I would say that someone who is installing an antenna mast and relies on a General Electrical Forum of unknown entities for advice...and ends up with a FVCH 3 GHz satellite TV coaxial grounding block for an installation such as this...;)
Click to expand...

3 gig is just the max rating. Fine for use on TV. They are 99 cents apiece. OP could also use a 1 gig. They are 49 cents apiece.

I don't understand the ;).
 
This is a topic that I do not fully understand, but of great interest to me since I got my amateur ticket last year.

Antenna grounding serves several different purposes, including getting best signal, safety for static discharge, and lightning protection.

You can pretty much strike lightning protection from this discussion. There is some black art there which I would not trust to anyone except a lightning protection professional. NEC minimum requirements do not address lightning protection for antennas. That #10 for grounding the antenna is not even close to what is needed for a lightning down conductor.

Other than static pickup, I don't believe that grounding will make a difference to the signal quality for the antennas you are considering. According to the supplier's site, these antennas have a 300 ohm balanced output (think 'twin lead') without grounded elements connected to the feedline. If you switch to coax, you will do so at a 'balun' and the grounded shield will only run from the balun on down.

For static discharge, I don't believe that adding a ground rod will make a difference; simply connect the #10 to the intersystem bonding terminal.

If lightning does strike your installation, using the #10 and not adding additional grounding, you can expect major damage. As I said, this is NEC minimum and _not_ lightning protection. If you want a system where lightning can strike the antenna with a high likelihood of only minimal damage (say just to the strike termination point) then IMHO you will need additional ground electrodes, grounding conductors on the order of #2 Cu, and professional design.

As I said: the above is speaking outside of my professional experience, so spice with a large grain of salt.

-Jon
 
ritelec said:
Yes. When you are unsure about something you should just go ahead and wire away.

Instead of going to a forum to discuss things.

Like grounding an antenna as running as straight a run as possible , but there's a large soffit so there will be no "straight" run to the earth. Now what. As possible ???

Suggestion for an inexperienced antenna grounder ?

If you can please try to reply with no sarcasm. If you can.
Click to expand...

It's hard for me, I know. I am a curmudgeon and have xxxx resting face.

So, I am going to assume that your mast does not go to the ground...that it is likely roof mounted...? If the mast is straight to the ground, then you can use the mast to affix the lead.

I don't believe in reinvention, so I follow the code and handbooks (including the ARRL antenna handbook, mine date to the 15th edition) pretty devoutly.

You might recognize the guy on this page.

And another link, same guy.

better...?:D
 
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ritelec said:
Yes. When you are unsure about something you should just go ahead and wire away.

Instead of going to a forum to discuss things.

Like grounding an antenna as running as straight a run as possible , but there's a large soffit so there will be no "straight" run to the earth. Now what. As possible ???

Suggestion for an inexperienced antenna grounder ?

If you can please try to reply with no sarcasm. If you can.
Click to expand...

None of the grounding the NEC requires will protect from a direct hit. The requirements of down conductors and coax are very different. You run your coax as straight as you can. This will make the shortest run, which is VERY important with OTA. I don't have cable or satellite. I use OTA. There is a huge amount of signal loss in coax at 35+ feet. Keep that short as possible.

All you are putting up is a TV antenna. There used to be millions of them installed with no grounding at all. I think you are putting too much faith in an NEC grounding system. If your antenna gets a direct hit, nothing the NEC requires will mitigate any damage. A ground rod is very high resistance. A proper lightning protection system uses a grounding electrode system that consists of many or large electrodes. There are also air electrodes and down conductors. You are not installing lightning protection system.

Grounding the shield and bonding to the intersystem conductor protects against a 120/240 fault and not much more than that.

A minimum installation has been proven safe for decades. Run your coax as short as possible and bond it to the terminal block and call it a day. Adding ground rods isn't a bad idea, but it may not even help. The most important thing is to make sure your antenna grounding is bonded to the AC mains system.

In our area, a single ground rod 8 feet in presents an impedance of over 1000 ohms. Ground rods are very overrated.
 
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