Tower for CB Antenna?

[UnidenBC92XLT]

Fixing to put up a 35' tower for my Sirio Tornado 27. My question is what do I need to do to ground it properly? It will be cemented in the ground at the base approximately 3' deep. It has 3 pipes with the cross bars. I plan on fastening 2 of them to the eve of the house. I have a metal roof and the soffet is metal also. I will be bolting it down strait to this. Then I plan on putting a 8' ground rod beside the tower. Is this sufficient enough? Will it matter that the tower will be bolted touching the metal roof? Thanks!!

 

[mmckenna]

The grounds need to be bonded to the house ground, per NEC code.
If you are in a lightning prone area, Ground each tower leg to it's own ground rod, then ring all the ground rods together using a heavy cable. Ground the outer shield of the coax near the top of the tower and near the bottom of the tower.
Install a lightning arrestor where the coax enters the house.
Ground the radio and all your shack equipment.
Again, all grounds need to be bonded together.

Might sound like overkill, but that is what you'd see at a commercial site.

At minimum (this won't meet any codes) you need at least one ground rod at the base of the tower and bond to the house ground. Lightning arrestor before coax enters the house.

Ideally you want to give any energy a safe path to ground that doesn't involve passing through your radio. A direct lightning strike will likely do damage even with all of this, although a good installation can survive a strike.
Direct strikes are not the only thing you need to be concerned about. Nearby strikes can induce enough energy into nearby conductors (cable, tower, etc) to cause problems. Also, strong winds and rain/snow can induce static electricity into your system. Give it a safe place to go.

 

[mmckenna]

Also, don't bury the tower section in the concrete. Get the proper base designed for this. The base of the tower needs to have clear weep holes in the legs to let moisture out. If you sink that section in the concrete, it'll block those holes and water will build up and slowly rust out the tower from the inside out.
If you can't find the correct base, make a base out of a metal plate with matching pins to bolt the tower to. Bolt the base down to the concrete. Really advise to use the right parts from the manufacturer.

Touching the metal roof or not, doesn't matter.

 

[mmckenna]

Find a copy of the Motorola R56 grounding document. Follow that and you'll be good. It's sort of the "bible" for grounding.

 

[UnidenBC92XLT]

When you say tie it in with the house ground do you mean the ground rod at the light pole? So you would dig a hole across the yard to tie the grounds together? I always unplug my radio if I'm not home or if its suppose to storm or anything at all. The coax and 110.

 

[mmckenna]

The electric service entrance panel for your home should have a ground wire going to a rod or the concrete reinforcing rod. That should be the main grounding point for your home. You should (according to the National Electric Code) bond your tower/RF grounding system to that point.

The reason is you want -all- your grounds at the exact same potential. If you have equipment grounded to separate points there exists the possibility that one ground can have a higher voltage potential than the other. That means someone touching your radio and another appliance in your home at the same time could get a shock.

Might be a good idea to consult with an electrician or at least do a bunch of research on this.

 

[K7MEM]

I have a tower very similar to yours. I purchased mine used without a base, so I made my own. I used some very large fence hinges and rebar to make a tilt over mount. That way I can easily lower the whole tower for maintenance. If you go to a hardware store that caters to ranchers, you can find some pretty sizable hinges.

The concrete base extends out of the ground about 3 inches and has a sloped top. This helps to keep water from pooling around the legs. I live in the high desert (5,300 ft), so I don't get a lot of rain anyway, but its good to keep as much water off of it as possible.

I also secure the tower to the roof of the barn (that is where my radio room is) using several lengths of angle iron. The roof is metal. I oriented the tower in it's base so that two of the legs are perpendicular to the roof edge. The lengths of angle iron can then span two legs and be secured to the roof.

In the spring we get very high winds, for long periods, and the tower is very stable. I also installed a pulley and rope at the top so that I can raise/lower dipole feed points without having to lower the tower.

Martin - K7MEM

 

[JayMojave]

Hello UnidenBC92XLT:

Good advise from K7MEM there, as a tilt over tower is great for allowing the antenna to be tuned and brought back up without climbing a tower. Iam sure a tilt over base piece can be made to make this work.

Grounding the legs of the tower with 8 Ft ground rods is a good call.

Having the tower touch or connect with a metal roof, I would advise against that. In high / low winds, snow, and some rain, the metal roof can be charged and use the tower as a path to ground resulting in a broad band noise heard ( something like a siren or racing type noise ) in the receiver. I've seen this happen in a few installations.

For added lightening protection in high lightening areas, I would suggest the coax or coaxes be connected to Lightening Protectors (or arc over protectors) connected to ground rods before they enter the house or barn. On top of the Mountains at repeater sites, over looking the LA Ca area the new installations have the large coax rolled up into a 3 foot diameter then connected to a Lightening Protector then entering the utility building. According to the guys installing this coiled up coax its the last ditch method of protecting from a Lightening Strike. As many repeater sites have had a lot of Lightening damage.

Let us know how you make out there, always good to see towers go up. Good luck.

Jay in the Great Mojave Desert

 

[talkpair]

The reason is you want -all- your grounds at the exact same potential. If you have equipment grounded to separate points there exists the possibility that one ground can have a higher voltage potential than the other. That means someone touching your radio and another appliance in your home at the same time could get a shock.

This is probably even more important if your roof and soffit already have some unintentional path to good ground. These unintentional paths could be from electrical light fixtures attached to the soffit, an electric meter attached to steel or aluminum siding, or metallic vents extending through the roof. These paths through sheet metal or aluminum aren't short-direct paths and won't be able to carry the current of a lightning strike.

Lightning will use seek multiple grounds where available.
By tying the grounds together, the lightning only 'sees' a single ground.
When you bury a short/direct piece of wire or cable from the tower ground rod to the power ground rod, you greatly reduce the scenic, less direct route to the power ground by providing an express route.

This is why the electrical service is bonded to the water service entrance. In the event of a close lightning strike to power, damage to electric water heaters, garbage disposals, etc is reduced or eliminated because the bulk of the current will be carried to the water entrance ground via that bond wire and not through the house wiring and appliances.

 

[UnidenBC92XLT]

Ok I can get the grounds together easy enough. The only ground rod I know if is at the meter loop at the light pole that the electric company put in. I can run a ground wire underground from it to my tower ground rod. How could I still attach the tower to the house but isolate it from the metal roof? Maybe put some pvc around the poles before I attach it to the house.

 

[talkpair]

You can attach the tower to the house without isolation.

By bonding, the damaging current is carried through the wire/cable you provide instead of the metal roof and soffit.

 

[UnidenBC92XLT]

This is the ground at my power pole. It's 40' from where my tower is going. There is a big tree between my pole and where my tower is going. Also the line runs away from it so no way it can fall over the power line.

 

[BBB007]

I smell a ground loop.

Are you saying that your breaker panel for the house is installed on the power pole as pictured or in the house? Or is just the meter out on the pole?

If the breaker panel is in the house, there should be a ground rod that is attached to that panel nearby. That's the same house ground that your transmitting equipment will be referenced to. Most Home AC mains have the Neural attached to the house ground in the panel nowadays.

So if you bond the tower to the ground rod out at the power pole and not the house ground rod, you're setting yourself up for a potential ground loop and the problems and noise associated with that situation.

Great video on ground loops here:

https://www.youtube.com/watch?v=GS-6jBk9YPM

 

[KC4RAF]

Just my 2 cents:

Check at your service panel in your house and double check for a ground rod within a few feet of the service going into your panel.
Down here in the sunshine state; all home's must be grounded at the service panel in the house.

 

[UnidenBC92XLT]

I smell a ground loop.

Are you saying that your breaker panel for the house is installed on the power pole as pictured or in the house? Or is just the meter out on the pole?

If the breaker panel is in the house, there should be a ground rod that is attached to that panel nearby. That's the same house ground that your transmitting equipment will be referenced to. Most Home AC mains have the Neural attached to the house ground in the panel nowadays.

So if you bond the tower to the ground rod out at the power pole and not the house ground rod, you're setting yourself up for a potential ground loop and the problems and noise associated with that situation.

Great video on ground loops here:

https://www.youtube.com/watch?v=GS-6jBk9YPM

That pole is where the meter loop is. There is no ground rod in the house on the breaker panel. The only ground in the house is the huge one that's ran with the main power coming into the house. The only ground that on a rod into the ground is at the service pole that the power company done. The transformer and meter is grounded to this rod. I haven't seen any ground ran to any house breaker box except the main one that comes from the grounded meeker loop at the pole.

 

[UnidenBC92XLT]

I smell a ground loop.

Are you saying that your breaker panel for the house is installed on the power pole as pictured or in the house? Or is just the meter out on the pole?

If the breaker panel is in the house, there should be a ground rod that is attached to that panel nearby. That's the same house ground that your transmitting equipment will be referenced to. Most Home AC mains have the Neural attached to the house ground in the panel nowadays.

So if you bond the tower to the ground rod out at the power pole and not the house ground rod, you're setting yourself up for a potential ground loop and the problems and noise associated with that situation.

Great video on ground loops here:

https://www.youtube.com/watch?v=GS-6jBk9YPM

That pole is where the meter loop is. There is no ground rod in the house on the breaker panel. The only ground in the house is the huge one that's ran with the main power coming into the house. The only ground that on a rod into the ground is at the service pole that the power company done. The transformer and meter is grounded to this rod. I haven't seen any ground ran to any house breaker box except the main one that comes from the grounded meter loop at the pole.

 

[UnidenBC92XLT]

This is my fuse box. I do have one stray ground going to the ground bar on the left side. I assume its going to the frame of the double wide. I know when we put this home in back in Dec 2002 I assure you there wasn't no ground ran from a rod to the breaker panel inside the house. The only ground is coming from the meter loop outside that's on the pole. My grounds in my box are on a ground bar on the left and right. Not even on the same bar as all the neutrals. Here are some pics.

 

[KC4RAF]

Yeah, you're electrical code doesn't

specify how far from the house main panel the ground rod is located. NEC doesn't specify any definite distance either. You could add one at your panel if your local code allows it.

 

[UnidenBC92XLT]

6th picture.

 

[UnidenBC92XLT]

specify how far from the house main panel the ground rod is located. NEC doesn't specify any definite distance either. You could add one at your panel if your local code allows it.

I dont understand what you mean my electrical code doesn't. I'm going to say its 70' from the ground rod at the pole to my breaker box in my house. There is no way to add a ground rod for my panel under my house as my house sits about 2' off the ground I can barley get under it. As far as code goes I have no idea. I live 10 miles from civilization and no inspections or anything here. Most when adding power to buildings and shops or whatever just do it themselves.