# Grounding necessary for OTA attic antenna



## RCKYMTN (Jan 14, 2006)

I have the AT9 and WB68 switch grounded. I have a channel master in the attic for OTA already grounded via an inline grounding block for the one OTA line I currently have running to one receiver (which was close to the outside grounding blocks). Now I want to split the OTA signal to run to more than the one TV - possibly two more TVs. 

I will have to drop the cables from the attic antenna and splitter into a couple of the upstairs rooms between the walls (similar to how a couple of my Directv runs are as well that run in the attic). How important is it to ground the attic antenna at all, and if one line is grounded is that okay if the other cables are not grounded? If each line or the antenna itself should be grounded, what are recommendations in doing this.

Thanks...


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## Meklos (Nov 7, 2006)

RCKYMTN said:


> I have the AT9 and WB68 switch grounded. I have a channel master in the attic for OTA already grounded via an inline grounding block for the one OTA line I currently have running to one receiver (which was close to the outside grounding blocks). Now I want to split the OTA signal to run to more than the one TV - possibly two more TVs.
> 
> I will have to drop the cables from the attic antenna and splitter into a couple of the upstairs rooms between the walls (similar to how a couple of my Directv runs are as well that run in the attic). How important is it to ground the attic antenna at all, and if one line is grounded is that okay if the other cables are not grounded? If each line or the antenna itself should be grounded, what are recommendations in doing this.
> 
> Thanks...


Quick story....

In my 'less educated' youth, I had an antenna in the attic, with a long feedline to a shortwave receiver. A storm came through the area that night, and since I was usually diligent about protecting my equipment even then, I disconnected the feedline from the antenna.

That night, the feedline was laying on the carpet, the end almost touching the baseboard. Lightning struck something near the house, but did not actually hit the house. Nothing went through the roof, and the antenna did not go outside the attic.

The magnetic field from the lightning strike induced enough voltage on the antenna to cause a spark to jump from the feedline to the baseboard, caused the carpet to catch into a smoldering fire, and scared the holy crap out of me.

Gound it, if you care about it.


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## bret4 (Nov 22, 2006)

Grounding can help get a better signal sometimes. May not notice it on an indoor antenna. It is more to draw off static in a lightning storm to help prevent a lightning strike. No ground is a guarantee that your TV or anything else will survive if it is hit.

Your antenna being in the attic is no more likely to be hit by a lightning strike than anything else in your house. Your gutters, if you have them are just as likely if not more likely to be hit. Some people have had lightning hit aluminum gutters and then it would get into the wiring through a wall frying a bunch of things in the house.

Many years ago one of the gutters on my house was glowing with sparks like little ball lightning flowing off of it during a lightning storm. I had a large tower with a bunch of Ham radio antennas on it that was fully grounded and it didn't do the same on that day. So grounds can be helpful but I would worry more about my aluminum gutters than an indoor TV antenna. Of course having said that someone will say they were hit by lightning on an indoor antenna. (Just beat me to it, post #2) If it makes you feel better I would ground it. Sure can't hurt. Just know that your TV and anything hooked to it may still be burned up. Not much can stop a powerful lightning bolt from going where it wants to go. Grounding to bleed off static buildup can help prevent some strikes from happening. 

Also don't think inline grouding blocks ground and antenna. You have to run a ground wire to those blocks to ground rods in the ground outside. It would be a good idea to ground any pole that your antenna is mounted to. This includes the dish mounting pole. 

Funny D* installers didn't seem to care about grounding when they were at my house. Wonder if they ground dishes when they mount them on the roof? (my dish is low on a fence not that helps much.)


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## hasan (Sep 22, 2006)

RCKYMTN said:


> I have the AT9 and WB68 switch grounded. I have a channel master in the attic for OTA already grounded via an inline grounding block for the one OTA line I currently have running to one receiver (which was close to the outside grounding blocks). Now I want to split the OTA signal to run to more than the one TV - possibly two more TVs.
> 
> I will have to drop the cables from the attic antenna and splitter into a couple of the upstairs rooms between the walls (similar to how a couple of my Directv runs are as well that run in the attic). How important is it to ground the attic antenna at all, and if one line is grounded is that okay if the other cables are not grounded? If each line or the antenna itself should be grounded, what are recommendations in doing this.
> 
> Thanks...


A ground of the length that would be required on an attic antenna would provide no lightning protection whatsoever. The long ground lead (from the antenna to wherever it runs to eventually get to "ground") would have so much inductance that it would be seen by the induced strike as a large resistor. There is no effective protection for typical consumers from direct strikes, so let's not even talk about that. To properly protect against direct hits costs many hundreds of dollars, perhaps thousands. Safety grounds (preventing electrical shock) is quite easy.

It is pretty unlikely that your attic antenna would represent the shortest (read as lowest impedance) path to ground, so lightning is not that big of a problem, and there isn't really anything you can do that will help the situation anyway.

What you should be concerned about are two things:

1. Surge protection: make sure every piece of equipment surge protected.

2. Protect your most delicate and expensive equipment with a UPS.

The HR20 should be plugged into a ups if you are in a lightning prone area. Your TV, if powered by a lamp (like DLPs) should be plugged into a ups to keep the bulb fan going for a short period of time AFTER a power failure.

If you go right to the UPS solution, you get both protection for power winkies during thunderboomers and surge protection at the same time. It is a very wise investment. Forget the attic antenna ground...it's a mirage, invest in a UPS for the HR20 and TV and you end up with the best and least expensive protection for both.

Lightning protection is a very involved science, some say art. If you have an outside antenna, well elevated, there are things to do that can help quite a bit. In an attic, there is no practical solution. (and the risk is very low) If you want to learn more about "real" lightning protection, go to the Polyphaser web site (google it), and you will see what is really involved.


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## techman (Oct 10, 2006)

Interesting that you say that about my latest install and grounding. I recently had a Slimline antenna and multiswitch installed to go with my HR 20. Previously I had everything from my antenna grounded with grounding blocks and a good ground round right near where the blocks were located. My installers did not use the grounding blocks and instead ran a ground wire from the multi-switch. I didn't see that part of the installation until they were gone but thought that was a rather interesting way to ground things. If you read the electrical codes that come with all types of amtennas, they seem to be pretty specific about using grounding blocks on each line and a ground rod.


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## hasan (Sep 22, 2006)

techman said:


> Interesting that you say that about my latest install and grounding. I recently had a Slimline antenna and multiswitch installed to go with my HR 20. Previously I had everything from my antenna grounded with grounding blocks and a good ground round right near where the blocks were located. My installers did not use the grounding blocks and instead ran a ground wire from the multi-switch. I didn't see that part of the installation until they were gone but thought that was a rather interesting way to ground things. If you read the electrical codes that come with all types of amtennas, they seem to be pretty specific about using grounding blocks on each line and a ground rod.


All of that is very good for "safety grounds", which is all the NEC cares about (National Electrical Code). None of it does much (with extended ground wire runs) to prevent lightning damage. Again, if anyone wants to know how "real" lightning protection is done, go to the polyphaser site.

I'm certainly NOT saying don't follow typical installations guidelines. I am saying for an attic antenna, where the ground run is going to be several tens of feet, there is no lightning protection whatseover.

The proper way is to have all feedlines terminated in a protective block OUTSIDE the house, just before entry, with a low inductance (very short, very thick or very wide copper banding) connection to real earth...but that's just a start, not the finish. It is not possible/practical to do this with an attic antenna.

There are also possible insurance issues with failing to follow NEC guidelines, but that's pretty rare too. For all practical purposes, an attic antenna is considered and "indoor" antenna and does not require any special grounding. Typically the house wiring and gutters represent a much lower impedance path to ground for lightning than the "floating" attic antenna.

In this particular case, the focus should be on surge protection/ups'ing the delicate electronics.


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## RCKYMTN (Jan 14, 2006)

Thanks for the input..., from what Hasan is saying, this makes sense (and clarifies)for me and that was the my main issue - how in the heck would I run a ground from up in the attic to the outside ground? It would be about 50 ft - so that gives me some comfort that there is nothing I can do for grounding an attic antenna other than what Hasan suggested for surge protection and UPS (at least the surge protection for now).

The posts though bring up another concern on my AT9 dish and the multiswitch. There is a grounding rod going from the dish, then through the multiswitch to the grounding area into the ground (which is the main copper water supply for the house). I have had several installers over the years (the first ones did not even do any grounding, and had to have them come back out). However, only one line from the dish/multiswitch has a grounding block. How important is it for the other cables coming from the multiswitch to the receivers to have the grounding blocks (primarily for safety purposes). Again, the dish and the multiswitch are grounded.


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## hasan (Sep 22, 2006)

RCKYMTN said:


> Thanks for the input..., from what Hasan is saying, this makes sense (and clarifies)for me and that was the my main issue - how in the heck would I run a ground from up in the attic to the outside ground? It would be about 50 ft - so that gives me some comfort that there is nothing I can do for grounding an attic antenna other than what Hasan suggested for surge protection and UPS (at least the surge protection for now).
> 
> The posts though bring up another concern on my AT9 dish and the multiswitch. There is a grounding rod going from the dish, then through the multiswitch to the grounding area into the ground (which is the main copper water supply for the house). I have had several installers over the years (the first ones did not even do any grounding, and had to have them come back out). However, only one line from the dish/multiswitch has a grounding block. How important is it for the other cables coming from the multiswitch to the receivers to have the grounding blocks (primarily for safety purposes). Again, the dish and the multiswitch are grounded.


If the dish is low, and the cable run from the one cable to your ground block is relatively short, I wouldn't worry about it. My AT-9 is only about 9' up and tucked in the corner of the junction between our greenhouse and the addition. I have no ground block connections on that dish at all. It is surrounded by many other conductive high objects (including a 66' metal tower), which affords quite a bit of "alternate target" area.

My other dish is up about 7' on the low side of the garage roof. I have ground blocks and a rod (of course) about 60' away from the dish, next to the house where the two cables come in to the house.

As far as safety is concerned, all the LNB's have a common ground, as well as the multi-switch, so there is no "electrical safety" issue.

If your dish is up in the air, like on the peak of a roof with no other "attracting" high metal objects, I would make sure that every coaxial line was terminated in a grounding block to a common ground rod at the entry to the house.


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