Grounding an Antenna....

dkreichen1968

Moderator
Staff member
#21
The following is from the Channel Master antenna istallation guide.

"The NEC requires that the antenna mast and mount be grounded directly. No splices or connections are allowed in the ground wire between the mast and the ground rod.

First, attach one end of a No. 8 or No. 10 copper or aluminum ground wire to the antenna mast. One of the bolts on the mount can be used as a fastening point. Masts that are painted or coated must have their coating scraped off around the area where they contact the mount. This will ensure an electrical connection between the mast and the mount. It is vital to get a good, solid connection. (Once the mast is attached to the mount, any scraped off portion that is exposed should be recoated with paint or other sealant.)

Next, run the ground wire to ground as directly as possible. Standard wire staples can be used to secure the ground wire against the side of the house. Avoid making 90° or sharper turns with the ground wire. A lightning charge has difficulty making such a turn and therefore may discharge into the house. Make ground wire bends as smooth and as gradual as possible. The ground wire must be connected to a ground rod. Water pipes or plumbing fixtures are not acceptable. A good copper-coated steel ground rod driven at least 3 feet into the ground is required. (My Note: Ground rod isn't required by NEC, but Channel Master doesn't consider a water pipe ground to be adequate protection.) Special clamps that provide a solid connection between the ground wire and ground rod should be used.

It is not just the height of an antenna that makes it susceptible to lightning strikes. Antennas and transmission line can accumulate static electrical charges that also increase the changes of lightning hitting an installation. To properly “draw off” this static electricity, a small device known as an antenna discharge unit (Figure 6-3 shows grounding block for 75 ohm coax) must be included on the installation. The antenna discharge unit (also called a “lightning arrestor”) is connected to the transmission line at a point close to where the transmission line enters the house. One end of a ground wire is attached to the discharge unit. The other end of the wire is connected directly to the ground rod.

Installation of the antenna discharge unit is very easy, and detailed instructions come with each unit. An antenna installation is not adequately grounded unless both a mast ground and an antenna discharge unit (grounding block works for 75 ohm coax)are installed correctly."


When you think about it, you don't want a lightning generated charge running through your house on a water pipe or electrical conduit no matter what the NEC may allow.
 
Last edited:

MrPogi

Moderator, , Webmaster of Cache Free TV
Staff member
#22
I am always worried in a severe storm about the (admittedly slim) chance that lightning may strike while I am in the shower - or using the water - and travel the metal pipes and give me a helluva jolt. For that reason alone, a seperate rod for grounding makes sense. Plus, the water pipes may be close to a gas appliance, think about that risk.

My house is all pvc / pex so its not an issue, I can't ground to a pipe. My question, how the hell do I drive a rod the recommended 6 FEET into the hard Utah soil?
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#23
... My question, how the hell do I drive a rod the recommended 6 FEET into the hard Utah soil?
Pogi,

I googled auger rental and the smallest size I found was 4", so that won't do. However, the last time I was at Home Depot I saw 3 or 4 foot long drill bit extension shafts meant to be used inside walls for adding wiring. I have one that is 13" long and it has a setscrew to clamp any drill bit with a 1/4" shank. If you could create a "pilot hole" I bet you could pound your ground rod 'home' pretty easily. :icon_beat:

Jim
 

n2rj

Moderator
Staff member
#24
My house is all pvc / pex so its not an issue, I can't ground to a pipe. My question, how the hell do I drive a rod the recommended 6 FEET into the hard Utah soil?
You're worried about one rod? I drove more than 30 in the ground here for my ground field.

No I didn't use a sledge hammer! I used a rotary (demolition) hammer and a ground rod driver bit. We have rocky soil here and it took an average of 10-30 seconds to pound in an 8ft ground rod. Check your local rental store and see what they have. The advantage of using the demo hammer (apart from not breaking your back) is that it doesn't mushroom the top of the ground rod.

If you can rent the bit or borrow one, that's fine. Otherwise they're expensive (~$100). You can also check your local sparkys to see if they are willing to drive the rod into the ground for you. Otherwise you could use a sledge hammer, but that can be tedious (and dangerous!)

I would not recommend using an auger or digging a hole then backfilling. For an effective, low resistance ground connection you need to drive the rod into undisturbed soil.
 
Last edited:

n2rj

Moderator
Staff member
#25
Another tool I have seen is basically a sleeve that fits over the rod and you move it up and down and the weight drives the rod down. I don't know how effective it will be in rocky soil but it's made by Erico which is the same company that makes cadweld (exothermic welding products.)

ERITECH

Some have even suggested using a post driver which I have tried with limited success.

Eye protection and gloves are recommended.
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#26
Ryan,

That tool is a slide-hammer. A common tool that works well for removing stubborn brake drums, axle hubs, etc. in the automotive world. Good idea.

Jim
 

MrPogi

Moderator, , Webmaster of Cache Free TV
Staff member
#27
Lots of ideas, but being the cheap sniveler, I would like to avoid the rental option. Or the "major tool purchase" option.

That being said, I'll have to do something here soon if I want to move out of the attic.
 
#28
When you think about it, you don't want a lightning generated charge running through your house on a water pipe or electrical conduit no matter what the NEC may allow.
You may be dead wrong. In a house it is critical that any two parts of your house that can carry electricity be grounded together at the same point. It is the potential difference between the electrical ground and the water pipe that can kill you and damage your equipment.
 

MrPogi

Moderator, , Webmaster of Cache Free TV
Staff member
#29
You may be dead wrong. In a house it is critical that any two parts of your house that can carry electricity be grounded together at the same point. It is the potential difference between the electrical ground and the water pipe that can kill you and damage your equipment.
The electric and plumbing be grounded together to the SAME ground as the antenna, right?

since the electric already has its own ground, then I should run a NEW ground to my ground rod, without having to disconnect the current grounding wires? (since disconnecting that would be almost impossible)
 

n2rj

Moderator
Staff member
#31
Lots of ideas, but being the cheap sniveler, I would like to avoid the rental option. Or the "major tool purchase" option.

That being said, I'll have to do something here soon if I want to move out of the attic.
You can also try a piece of iron pipe with a cap on the end. Cheap, but not sure how effective.
 

dkreichen1968

Moderator
Staff member
#32
You may be dead wrong. In a house it is critical that any two parts of your house that can carry electricity be grounded together at the same point. It is the potential difference between the electrical ground and the water pipe that can kill you and damage your equipment.
So ultimately your antenna ground needs to be connected to your houses main electrical ground. So if you run one wire from your antenna ground to the mast, one wire to the grounding block and one wire to a water pipe, or other tie in to your general electrical ground it would keep all of your potentials the same. I, and I believe Channel Master, have a big problem with allowing the main portion of a lightning strike pass anywhere through your house on its way to ground. After all if you just hook to a water pipe, all those heat producing electrons are going to have to travel the water pipe to ground. Electricity is always going to take the path of least resistance.

Okay, I just read a post on another forum that makes the NEC make more sense to me. A water pipe ground must be connected within 5 feet of where the waterpipe comes into the house. (i.e. 5 feet from ground, earth, that big electron sink under our feet.) So, if your waterpipe ground is on the other side of the house it doesn't meet NEC. On the other hand a ground rod is a direct connection to earth ground (in theory). Now, what is the potential, potential between two isolated earth grounds? Why goes Winegard show a connection to your general electrical service ground and Channel Master never mentions it in their installation manual and says you must use a ground rod? Is everyone, including the "experts", confused about this?
 
Last edited:
#34
ok, I haven't grounded my antenna but I have done the following things:

1. Even though my antenna is mounted outdoors, no part of it is visible unless you're on my patio, standing directly under it. It is hidden by a balcony above, which is in turn covered by a roof. It is 100% under cover from the elements...not even rain can get to it, unless it's raining upside down.
2. I have my cable running through my doorway (when it gets warm out, I'll run it through the wall) and into a coaxial surge protector before it hits the TV

I assume this is enough to get away without grounding, as I have read that attic-mount units don't need to be grounded, and for all intents and purposes I consider this to be akin to an attic mounted unit. Is that ok?
 

n2rj

Moderator
Staff member
#39
That I'm not sure about. I don't think NEC requires it as your house would prevent lightning strikes to the antenna. That's not to say it isn't a good idea though.
 

vayankee

DTVUSA Jr. Member
#40
Thank you, Ryan! That was fast. I'll go through this thread to see what I should do about that. We blew one tv here about 12 years ago, so I am concerned about lightning.
 
Top