Antenna Grounding ~ Shared with hot tub ground rod?

[G3MiNi]

I am getting ready to raise my scanner antenna by placing it on my roof on a RS tripod with mast. I have an 8' grounding rod in a perfect location near this installation, but it is used to ground my hot tub. Can I share this rod with both the tub and the antenna? Or would there be electrical interference introduced from the tub? Might a lightening strike to the antenna fry the hot tub electronics if I do it this way?

Good idea? Bad idea?

I understand if I need to drop another 8' rod into the ground for the antenna that it needs to be at least 16' from the hot tub rod. If my math is correct?

--Kevin

 

[petey_racer]

I hate to say it, but the ground rod at your tub is NOT "grounding" it, nor is it required, nor is it code complaint. I have NO idea who ever got the idea that a ground rod was required at a spa, it NEVER was. It also serves absolutely NO purpose there.

I would check the NEC for the requirements to connect your antenna to an electrode. If needed when I get home I can give you some text to read.
You should sink another rod but it does not have to be 16' from the tub. I am curious as to where you got this 16' number from.

 

[AlmostHandy]

Hello. I'm kind of new to all of this, and had a quick noob question.

When you say "8' grounding rod", do you mean that the rod is 8' long total, and is partially buried, like a fencepost, or do you mean that some other length of rod is buried 8' deep below the surface?

Also, when you bury a grounding rod, do you sink it straight into the earth, and pack dirt in around it, or is it anchored in some way with concrete/sand/etc., more like a fencepost?

Can I use a preexisting fencepost as a grounding rod?

 

[KC4RAF]

8 foot ground should gone straight down

in the earth and leave a few inches above the ground to connect to, usually a grounding clamp. No concrete. Concrete is not a good conductor. No to the fence post.

 

[kb2vxa]

"I have an 8' grounding rod in a perfect location near this installation, but it is used to ground my hot tub. Can I share this rod with both the tub and the antenna?"

Waddaya nuts??? It gives a whole new meaning to "hot tub" now doesn't it? (;->)

 

[G3MiNi]

Ok, I'll take these one at a time ...

petey_racer ~ Apparently I am a fool. I'd been told 'years' ago to run a ground from the hot tub's control box grounding plate to a grounding rod. After reading your comment, I went out and did some reading on this subject and this method is highly NOT recommended. So I just freed up an 8' grounding rod to use for my antenna. I'd read other posts in the forums here which discuss the distance between grounding rods. This may have dealt with multiple rods connected to the same system, but I believe this was a general rule of thumb. If the rods are too close together and one takes a shock, that surge can travel to other nearby rods. I'd read to sum up the length of each rod to determine the appropriate distance between the rods. In my case 2 x 8' rods = 16' ... but, again, I'm not totally sure I understand this quite yet; Hence the question-mark after my math summary in my original post

To answer other questions, AlmostHandy, yes the rod is 8' in total length and as rafdav said, it's hammered straight down into the ground with a few inches showing above ground level for the clamp. Don't use a fence post as the bottom of it may not break through the freeze line. Dirt within the freeze line becomes honeycombed and does not make perfect contact with the fence post (especially through concrete). Use a real grounding rod whenever possible. You can get them at your local hardware store.

Waddaya nuts??? It gives a whole new meaning to "hot tub" now doesn't it? (;->)

I'm still laughing. In reviewing my original question - it was pretty dumb (LOL) ... basically I was asking if it was wise to connect a lightening rod to a big tub of water, then soak in the water and see what happens. The tub is no longer connected to the rod and the antenna will be soon.

Thanks to all for your input.

 

[OceanaRadio]

To help clarify your understanding of ground rod placement, the minimum separation of sum-of-the-depth distance apart ensures maximum efficiency from each rod's placement, and is not a safety issue per se. Placing rods closer together simply limits their individual effectiveness in discharging the most energy possible underground. Multiple ground rods must ALWAYS be bonded together, including a bond to the structure's electrical service-entrance ground, no matter what purpose or systems the external ground rods are serving.

One other poster mentioned concrete is a poor conductor, and this is not true. Buried concrete is a very good conductor, better than many soils. When lightning protection systems are properly bonded to reinforcing rod inside subsurface concrete, they form an excellent connection with earth. There are also chemical admixtures that when added to concrete make it hands-down the best conductor, second only to solid metals, but wih a lot more surface-area than any number of ground rods.

Structures that have this type of "Ufer Ground" (concrete grounding system) pose a challenge to anyone trying to bond a new external ground rod system, because they can never locate the point where the AC entrance ground bonds to the subsurface concrete. It was buried during construction and can be impossible to locate later. In that case a new ground rod must be added for the AC entrance ground, and that connection bonded to the new external ground rod system.

Jack

 

[G3MiNi]

Jack - wow! Great info! I have a couple followup questions for you... if you don't mind. I have an 8' ground rod (already buried) to which I wish to connect my antenna/mast. The rod will only be connected to my antenna ... so then:

1) Does this rod need to be connected to my house's main ground? If so, can this be accomplished through a grounded outlet, or must a dedicated wire be run the full distance from rod to rod? My house's main grounding is quite some distance and many concrete barriers away from the antenna's ground rod.

2) My antenna is about to be mounted to an RS tripod on my roof with a 15 foot mast. Where should the ground wire be connected? To the base of the mast? Closer to the antenna? Directly to the coax shielding? I'm just not sure.

3) Am I correct in my understanding that a grounding wire should never make any sudden turns off the roof, under the eves ...etc. I think I read that they should follow a 12" radius when making turns. Is this correct?

Thanks,
--Kevin

 

[petey_racer]

1) Yes, and NO, a connection to a receptacle is not appropriate nor safe.

2) I'd say anywhere on the structure is fine.

3) Yes.

I would try to get a hold of a copy of HEC Art. 810. You'd be surprised as to what is required to be safe.

Here is a start:
http://ecmweb.com/nec/electric_article_radio_television/

 

[Viper43]

Good idea IF your related tro Hannable Lector and like your humans well cooked!

Couldn't resist that one after reading it.

And yes, concrete is a good conductor, not mentioned above about concrete but concrete that is underground is almost always has moisture in it besides the steel used for stiffening.

V

I am getting ready to raise my scanner antenna by placing it on my roof on a RS tripod with mast. I have an 8' grounding rod in a perfect location near this installation, but it is used to ground my hot tub. Can I share this rod with both the tub and the antenna? Or would there be electrical interference introduced from the tub? Might a lightening strike to the antenna fry the hot tub electronics if I do it this way?

Good idea? Bad idea?

I understand if I need to drop another 8' rod into the ground for the antenna that it needs to be at least 16' from the hot tub rod. If my math is correct?

--Kevin

 

[OceanaRadio]

My house's main grounding is quite some distance and many concrete barriers away from the antenna's ground rod.

Kevin,

I see your questions were all well answered, but on the one point above - it is a bad thing for the radio room and/or antenna mast grounding points to be a long distance from the AC entrance ground point. Good design always places the antenna coax entry point very close to the AC entrance point. That being said, many (most?) of us face the same problem you have, they are a long way apart.

You can see how I dealt with that problem on my website at
http://members.cox.net/pc-usa/station/schematic.htm

Few may be as paranoid as that schematic might cover, but there are actually many more ground rods (and antennas) installed since I published the website in 2005. And, the many trees that surround me, several of which hold HF antennas, have all been struck, some numerous times. Some of my equipment is never shut down, and nothing is ever disconnected. Somewhat of a far cry from where I started, which included stuffing unplugged antenna coax into a mason jar in the shack. Once you see the inside of a station that suffered major damage from lightning, it can change your attitude a lot.

Happy New Year to all,
Jack

 

[G3MiNi]

Jack,

That's pretty impressive stuff. You have me thinking deeply about linking my grounds together. I live in the Sierra Nevada Foothills of Northern California and am "surrounded" by tall trees, many of which still hold old, but large, TV antennas at their peeks. About 4 or 5 years ago my wife and I were shaken from our bed when a lightening strike hit a phone pole down the street. This hit took out my DSL modem and my router, plus one cordless phone system in our house and fried some of the phone wires in the wall. I've lived it and I know what a nearby strike can do. Wouldn't want to know what a direct hit might do.

Our main service panel is on the exact opposite side of the house from my preferred grounding rod ... but not so far that I couldn't just run the ground from my mast directly to that point and abandon the other rod. I've never looked down to see if I can locate the houses ground as our main panel is located in a tight entry way where stairs cover the entry point under the house where I suspect our main ground resides. I'll be taking a look tomorrow . What gauge/wire spec should I run between the two poles if I decide to use the auxiliary grounding point?

Thanks again for the info.
--Kevin

 

[kb2vxa]

Well G3, I hope when you disconnected the rod you didn't disconnect the only protective ground on the control panel, pump, etc. If they're not grounded per the NEC through the protective ground conductor to the service entrance panel you still can have a "hot" tub.

Nah, you WERE a fool, now you are wise so how does it feel? Since you admitted it how does it feel to be a man?

 

[tonsoffun]

Nah, you WERE a fool, now you are wise so how does it feel? Since you admitted it how does it feel to be a man?

Warren,
You can always bring me to a laugh/smile, and very hard to do in the morning

Kevin, your wire should be at least #6 gauge. Your asking right questions, good for you.

Ron

 

[AK9R]

Multiple ground rods must ALWAYS be bonded together, including a bond to the structure's electrical service-entrance ground, no matter what purpose or systems the external ground rods are serving.

Jack, I'm isolating this point because I think a lot of folks miss it.

The implication from the OP was that the hot tub ground rod was separate from the ground rod at the electrical service entrance. Whether the OP uses the hot tub ground rod for his antenna or not, that ground rod, and any other ground rods, must be bonded together.

 

[jim202]

The subject of grounding antennas has been covered by I don't know how many threads over the course
of time on here and a number of other sites. What ever you hear or read on these sites is in most
cases based on the personal feelings of some of the miss guided people there. There are others that
will point you to do your own homework and come to your own conclusions.

With that said, you should spend some time looking through section 250 of the National Electrical
Code (NEC). Here you will find a number of references to grounding antenna systems, spacing
ground rods, bonding different ground systems together and as in your case, grounding of the
electrical system of a hot tub.

Another issue that most don't even think about is that the house insurance carriers even have
guide lines as to how your external antenna system should be grounded. In some cases, these
insurance companies have with held insurance claims from lightning damage due to the antenna
not being grounded or by the grounding not meeting certain specifications.

So it would be to your best interest to do some homework on your own and not believe all that
you may read on sites like this one. I have been in the electronics and radio field for well over
40 years now. About 15 years of that time I was building cellular communication tower sites.
Not that you need to go to the extent that the cellular companies do to protect their sites, but
they do stay working after taking a direct lightning strike.

It is not any one grounding item that does the surge protection, but all the different things that are
done to protect a facility. The electrical service, the telephone surge protection, the tower
ground, the building ground, the coax cable grounds, the grounding of the equipment racks,
the grounding of the chain link fence and so on all contribute to providing a total solution.

Do as you please, but also do your homework.

Jim

 

[G3MiNi]

Nah, you WERE a fool, now you are wise so how does it feel? Since you admitted it how does it feel to be a man?

My name is G3 and I am a fool. (this is where you all say, "Hello G3") .

Seriously, thanks to all for your help and support on this. I've learned more in the last 24 hours about grounding than ... well ... ever!

Jim ~ I will do some homework on this as well.

Thanks,
--Kevin

 

[AlmostHandy]

Some more noob questions, if y'all don't mind.

Does every house, everywhere, have a metal rod(s) in the ground nearby, 8' deep, that the main electrical panel uses to ground to, or are there some houses that may use a different type of grounding system?

Can any grounding site for a house be used to ground an antenna mast, or will I need to sink a separate 8' rod in the ground, just for the mast?

 

[code3cowboy]

Why the hell would your scanner be near your hot tub? DTMF tones are as erotic as Quick Call II.

 

[kb0nly]

Actually if your hot tub has a ground rod then leave it, as it should have an earth ground. Not sure where you found online that this should not be done. If you look at the installation instructions for many brands/models of hot tubs they are recommended to not only have a ground but a GFCI protected circuit to power them as well.

Removing the earth ground connection from the hot tub terminal panel is a big NO-NO electrically, but to each his own.

I know a guy that installs them for a living, the first thing he does is install a GFCI breaker in the panel feeding the hot tub, and then install a ground rod where the hot tub will be installed to ground the entrance panel at the tub. Just good electrical practice for any circuit branching off from your main panel. Sure you have the ground in the line supplying the hot tub, but for a ground the shortest route is best, hence the rod at the installation location.

Just install a new ground rod for the antenna install and leave the existing one alone.