I think most hams have spent far more time than they liked, trying to drive an eight foot long ground rod into the ground. Maybe that is why so few are properly grounded.
At any rate, some time back I was thinking, "There has to be an easier way". This question came to me on about the third, no... make that the second ground rod of the afternoon and many more to go. With basically a 100 foot tower that has the top array 30 feet above the top of the tower and a 80 foot underground run of conduit to get the cables in the house, I figured I'd need a good ground system. I figured one ground rod for each leg of the tower and then at least an 80 foot straight run away from the tower. I decided to tie these into a network as well.
The soil here is a clay loam mix at the surface, but by two feet down is solid clay. This makes driving ground rods a lot of work, but at least the soil has very few stones.
I thought of using a hammer drill, but mine will not take a shank as large as the ground rod. Then I started thinking that water makes a good drill when handled properly. I hooked a hose to a piece of conduit and although it did the job it needed more than a bit of refinement.
I came across a solid brass hose fitting at Lowe's
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I decided to use plain old thin wall metal conduit (emt). Either 1/2 inch or 3/4 inch will work even though the 5/8ths inch ground rod is larger than the 1/2 inch emt the hole will be larger than the conduit. I decided on the 3/4 inch for strength if no other reason. You can still bend the stuff if you try forcing it instead of letting the water do the work.
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| The hose fitting is just a tad over size, but small enough that the end will start into the tube. I used a "Dead Blow" rubber mallet to drive the hose barb into the tube. If you look closely you can see the conduit has expanded a little bit for the first inch. | I cut a piece of 18 gauge sheet steel to just fit inside the conduit. It extends into the tube for about a half inch. It extends forward about a quarter inch and extends about 1/16th inch outside the conduit. |
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| Another view of the steel insert brazed in place. | I wrapped Red tape around the 10 foot long piece of conduit at the seven and eight foot points. |
The drill ready for work. It helps to have a step ladder on which to stand when you start the hole. You have to hold the hose up so it doesn't kink at the top, shutting off the water.
Using the drill is kinda like imitating one of the old well machines. You start by turning the water on full, climbing the ladder with the drill and then placing the tip of the drill on the ground with the conduit held vertically. Unless the soil is very hard and dry the drill will begin to sink immediately. You then just keep raising and lowering the drill a few inches to a foot along with a bit of turning. Forcing the drill can plug the end, or in some cases, bend the conduit. It only takes a minute of two to get the hang of it. From then on you can drill an eight foot hole in about a minute to two minutes. Pull the drill out and just drop the ground rod in. The rod just drops right out of site with water gushing into the air. If the depth is right the top of the rod will be about three inches below the surface. Better too shallow than too deep. After all the drilling, the rod can be driven in another inch or two with just a tap or two from a 10# sledge.
There are three ground rods at the base of the tower with the bare copper running out at least 80 feet on each. There are eight foot ground rods CadWelded to the cable between every 8 to 16 feet. The run to the south parallels the back of the house and the conduit run that carries the coax cables from the tower to the basement. The old tower that was used for the Midland repeater for some years was about 30 feet south and 10 feet east of the present tower. it too had a fairly elaborate ground system which tied into the cable paralleling the back of the house.
A couple years back we had a new septic tank put in and they hooked the ground system while digging out the old tank. The results of that are going to require pretty much replacing the west basement wall.
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The ground rod in place with the trench for the cable |
Cutting the cable directly over the ground rod. |
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The "One Shot" CadWeld Cartridge |
Cartridge contents |
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Contents |
Form, bottom seal, charge, and top cover with igniter hole. |
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The form in place over the clean end of the ground rod. |
The ends of the cable butted together in the center of the form. Sand is packed around the form to to keep it and the melted charge in place. |
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Cutting the cable to fit. |
Pouring in the charge and the CadWeld doing its job! Warning: Do not look directly at the welding process! It is as bright as arc welding |
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The cooling charge |
The weld after the form has been removed. The cable has become part of the rod. I did this 30 times for the entire system. |
There is also a ground circuit around the shop with the station ground on the south side, two ground rods at the base of the 32 foot tower and it is all tied together with #2 bare copper. There is one more ground rod to add at the base of the mast for the 144/440 vertical on the north side of the shop and that will be tied to the ground rod at the north leg of the 32 foot tower.
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| Although not a good photo, this shows one of the three ground wires attached to one of the ROHN 45G tower legs. | Ground cable attached to the SW leg of the 32 foot tower on the west end of the shop. There is a 27 foot tall vertical on top of the tower. The cable curves toward the camera and to the right slightly. The ground rod is about 6 inches in front of the landscape edging and a foot to the right of the tower leg.. |
The grounding plate for the PolyPhasers (TM). Note the #2 copper cable at the right rear. This cable is bonded to one of the tower legs. along with five, eight foot ground rods. I'd have preferred to have located the bulkhead outside, just prior to the cables entering the basement, but that was not an option.
I'll eventually insert a drawing here to show the grounding layout for both systems.
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