Need Advice on Ground Installation New House Construction

[WA1KBQ]

We just poured the footers for a new QTH and I'd like some advice concerning antennas and grounding from a few of the wise old owls here while the opportunity still remains. Radio hobby will be arranged on the second floor and antenna will be just a dipole for 80 and 40 meters for now. What recommendations can you suggest for antenna lead-in, equipment ground and antenna counterpoise for likely future antenna work?

Thanks in advance!
Greg

[WBear2GCR]

What is your soil type and depth??

Will the back yard  have a tower? Or just dipoles between trees...

Where will the incoming electric service be compared to the upstairs shack...?

             _-_-bear

[WA1GFZ]

I ran a loop of #8 solid around the outside of the footers and brought both ends in with the water main. Being on the side of a hill I added two more #8s from the water main hole around both sides of the footer out to the property line. One was near the surface and the other went down the trench to the sewer connection. The far end sits in water since the water was 3 feet below the surface. Inside I bonded the #8s to the water pipe 3/4 copper and ran a #4 to the breaker panel. Panel also connects to 2 8 foot rods outside. The only mistake I made was to not run a couple more #8s out the water main hole to go up to the surface. I want to add a loop around the surface with spoks going away from the house. more is better

[Jim, W5JO]

To put down wire at this point would only be for lightning or electrical ground, which could be advantageous if you have poor condutivity.  However sometimes doing this ensures a place for lightning to strike so one never knows.

Your dipoles, being balanced, will not need a counterpoise, nor will a beam.  Height above terrain will be the factor to consider.  But if you plan any type of vertical or end fed wire, that is a horse of a different color.  Here too, I wouldn't put down wire just yet.  I would wait until construction is finished and you are ready to sod the yard. 

That is when I would put radials down and cover them with sod.  Remember radials more than an inch or so deep are worthless for RF.

[WA1KBQ]

What is your soil type and depth??
Soil is typical North Carolina red clay with a few inches of topsoil (previously farm land). Builder said the footers are 18" deep in order to get down to firm earth.

Will the back yard  have a tower? Or just dipoles between trees...
There could be a tower sometime in the future but just a dipole for now. You know how that goes... plans can evolve and change when the experimenting begins.

Where will the incoming electric service be compared to the upstairs shack...?
The entire second floor will be for the radio hobby so some of it will be directly above the incoming power service panel and some of it will be in a room on the other side.

[WBear2GCR]

What is your soil type and depth??
Soil is typical North Carolina red clay with a few inches of topsoil (previously farm land). Builder said the footers are 18" deep in order to get down to firm earth

Gee... that would never fly in the northeast... 4 feet or more to get below the frost line... heh.

Will the back yard  have a tower? Or just dipoles between trees...
There could be a tower sometime in the future but just a dipole for now. You know how that goes... plans can evolve and change when the experimenting begins.

Where will the incoming electric service be compared to the upstairs shack...?
The entire second floor will be for the radio hobby so some of it will be directly above the incoming power service panel and some ot it will be in a room on the other side.

I'm no grounding expert, but that upstairs location might have some issues in terms of finding a good RF ground for the whole area... dunno... there are some considerable distances to cover, and I would speculate that a 1/4 wave at 40m or 75m wouldn't be good! 

But it sounds like you can drive ground rods their freely - can't do that here at all...fwiw.

                  _-_-bear

[ka3zlr]

Congratulations on the New Home Construction OM, good for you...it's nice making a new place.... a New Home....Great...

My Advice........after being Hit directly twice...once on land line drop, second on the Stupid idea of connecting everything together............................I have Bad soil conductivity the all connected idea DOES NOT WORK ALWAYS.......................High tension came in on the ground system here...

Your feed line Home Power as per Building codes....spend the money on the Gooder ground rods...they do get expensive But....hey...new home OM..

Your Station, the point is to Distribute away, not draw to...and eliminate any possibility Loops...therefore, Have a Proper Power panel installed at the station location upstairs as Per Building Code with it's proper electrical ground let the electrician do his job there to that point.....Nothing goes to the footer...Not if i were building a new home...No Way in hell...

Antennas, never build any wire antenna directly over head for QRO...build to furthest point away always... For AM, My opinion, is first Duty Cycle friendly...Heavy Wire Heavy connections etc...Build it to take a beating ... keep it Simple Secondly...build to be able to drop the system at any onset of bad weather..ie.. Pulleys on ends rope lift...let it drop to the ground Avoid any chances any time possible of taking in a strike...we are Not a Broadcasting Corporation ...like i hear some of these stations on the air...we are Amateurs...You, your Home and family Comes first...Always....Verticals are different and stationary verticals require they're own set of rules Outside...

Station ground....Very simple but Heavy wire as per any Amateur Handbook specs...to ground rod away from home shortest distance possible...any connections from equipment to ground point done with copper flashing...that's what i do...no problems here...you can use as many ground rods you wish outside but get them deep and away from home...One single ground point exit...away from station...since I did this I've never had another Strike...

Never ever leave anything connected and Power main Off at station at all times not present install a hand break at power panel...believe me do yourself a favor at building time and save yourself any heartache...

This I've learned the hard way...Hope it helps...

73
Jack

[WA1GFZ]

No, not against the footer in the trench away from the concrete. I put the wire against the outside of the trench. It is bonded with #4 to the 3/4 inch copper main and single point ground in the breaker panel. My building inspector liked it. A wire in concrete will explode the concrete if it gets hit.  You never have too much ground.

[KA1ZGC]

Radio hobby will be arranged on the second floor and antenna will be just a dipole for 80 and 40 meters for now. What recommendations can you suggest for antenna lead-in, equipment ground and antenna counterpoise for likely future antenna work?

Hiya Greg,

I faced a similar situation earlier this year, and asked the oldbies what their experiences had been:

http://amfone.net/Amforum/index.php?topic=17227.0

As you can see, there are as many opinions as there are hamshacks.

Being on the second floor, any conductor to earth ground may well behave differently on the higher bands than it will on the lower bands. What provides a good ground on 75 might be hot with RF on 40 or 20. This was a bit of a dilemma, and while the responses were quite informative, I was still left to wonder if I should even attempt tying to earth ground.

I opted not to, and it has worked out fine so far. What I did instead was to make sure I had all the chassis of all the equipment tied by as low-impedance a path as possible to a common point; in this case, the transmitter rack. I did these one-by-one, and RF issues came and went in the process, but once I got the last few pieces tied in there were no problems with RF in the shack (or at least not into the equipment). Once everything had a common idea of ground potential, the Faraday theorem was satisfied and I had no issues.

The feedline from the shack is coax leading to a link-coupled tuner in a doghouse at the base of the antenna, which is fed with 450 ohm balanced line. No reference to actual earth ground anywhere in the path.

Broadcast AM stations with on-site transmitters deal with this issue all the time, and often RF issues are solved by lifting certain pieces of equipment from station ground. It's never cut-and-dry, and what works at one station may not work at another.

Having said all that, some very clever ideas were floated on that thread for dealing with a "hot" ground that you may want to look into. This is not to say you will have a hot ground, but if it does become an issue, there are many ways to approach it.

Good luck!

--Thom
Killer Agony One Zipper Got Caught

[N3DRB The Derb]

I think there is  much more need for a safety ground where everything is at the same grounding reference point. having different racks at different potentials to ANYTHING, including "ground", is NG IMO.

good rf grounds are hard to get and in practice, dont need to exist for most ham stations. If I was you, I would get as big as wire conductor up to that 2nd floor as you can... #4 insulated would be good. Then I would build a homebrew counterpoise tuner with a rf ammeter on it  and tune for maximum current down to your rods.

use nothing but splitnutted and bonded (silver soldered with a torch at a minimum) or cad welded if you can afford it to make your wire/wire and wire / rod bonds.

heres some pix of my install.. gotta go take em, will show shortly.( not finished) to give you some ideas.



 

[WA1GFZ]

Bottom line lightning is all about ohms law. If you can't pass the current, you get voltage. When you pass current the voltage across that conductor length induces voltage by the transfer impedance. The lower the resistance the lower the voltage developed or induced. 

[k4kyv]

Bottom line lightning is all about ohms law. If you can't pass the current, you get voltage. When you pass current the voltage across that conductor length induces voltage by the transfer impedance. The lower the resistance the lower the voltage developed or induced. 

Because of their extremely fast rise time, lightning pulses should be treated more like rf than like DC or 60~.  In addition to the heavy buried ground wire surrounding the perimeter of the foundation (but spaced a few inches away from the concrete), use at least two 20' long (or longer) buried radials at each corner, with an 8' ground rod bonded to the ends of each of the  radials.  I would use three  radials at each corner, one aligned with each foundation wall and a third one coming directly off the corner at a 45º angle from the others.  This will provide a good rf and lightning ground as well as a low-resistance 60~ and DC ground. 

If you are using a balanced dipole, the station rf ground is less important, but since this is new construction, I would go ahead and lay, or have the builder lay copper screening over the floor joists, with the pieces bonded together using silver solder, before the upstairs floor is laid, to establish a solid rf ground at the equipment level.  This should reduce rfi problems in the shack and out.

[KB2WIG]

This may be of interest in a discussion on grounding...

List-post:  <mailto:towertalk@contesting.com>

Jim / Paul / Doug and list:

I have been holding back from responding to this thread as I have responded to
this idea in the past, but I just couldn't hold back any more.

The exploding concrete concept is mostly myth not fact. If you look at the
referenced fig. 4 in the cited resource you see the vertical crack at the
surface of the concrete pier. There is no spalling or other evidence of
exploding concrete in this photo. My take is that this appears more like a
freeze-thaw crack given the mountain-top location. If indeed the water in the
concrete flashed to steam ( a big stretch) the water was there due to the crack
already being there. Concrete does not have free-water pockets incorporated in
it if properly placed and consolidated. The water is used up in the chemical
reaction of the concrete curing process. There is some free water in the
micro-pores of the concrete-sand-rock matrix, but in miniscule amounts. If the
crack is 1/8" wide then it is significant but to attribute it to a lighting
strike with lack of before / after data is bad science.

I have been engineering foundations for large power plants, manufacturing
facilities, stacks, towers, etc. for almost 40 years. We have always used Ufer
type grounding with an external ground grid and rods.  All tied together with
exothermic welded connections and 2/0 or 4/0 stranded ( heaven forbid! ) bare
copper cable. I have yet to see ,or been notificed of, any evidence of a
lightning strike induced foundation failure or explosion damage.

For the sake of good engineering practice and knowledge I remain open to all
information that shows that what we have been doing is dangerous and
inappropriate. I am focused on providing my clients with the best practical
engineering solutions to their projects.

Regards
Lonberg Design Group, Ltd.
H.S. Lonberg, P.E.,S.E.
President


 

[WA1GFZ]

Don,
We built a room like that at a work site. It is quite a big deal and expense burt it worked well. Might be easier to just do the shack area. Lightning is a BB pulse but most of the energy is at WF5 (RTCA DO160E) but I've seen WF2 100ns rise time crack caps. No ground means high voltage so are you feeling lucky.

[WA1GFZ]

Another issue I've been told (after I put copper tubing in my solar room slab) that concrete attacks copper. Still I have always thought it bad to run ground wire through concrete. K1JCL did Tom Vu ground system. Tom Vu might add his comments here. Big Al has done a number of beautiful sites.
I've shot lightning (man made ) down wire and made it jerk.
I wonder if the NEC has anything on it.

[AD5OL]

For what it's worth.......I live in a split level house, and the window in my room is about 8' agl. I built an entry panel out of a 4" x 24" x 1/8" copper plate set in a wood frame that the window sash closes on. To compensate for the extra length to reach the ground system, I used a run of 6" x 0.030 copper strap down to my ground system. The strap is bonded to the plate, and there are 3 UHF bulkhead feed throughs and two ceramic feed throughs for balanced lines.

Since I live on a shallow soil depth hill side with rock 5' or so down I installed 3 5' rods on 10' centers with a piece of 3 ga. bare copper wire brazed to each rod (Silver Soldered with Staysilv-15) and then silver soldered the 6" strap to the 3 ga. There is an additional 200' or so of 12 ga. bare wire radials run out into the yard buried about 3" deep also silver soldered to the 3 ga. buss.

Not sure if any of this excepr the long run to ground applies in your case, but in a second floor location, you do need a low Z grounding conductor.

Bill AD5OL

[WA1GFZ]

In the EMI world a good ground strap width is 20% the length.