+++++++++++++++++++ Ground Rod Notes Also see Grounding +++++++++++++++++++ From: "Guy Olinger" To: , , "Daniel L Brinneman" Subject: Re: [Elecraft] Is there a "grounding" Elmer on line? Date: Mon, 24 Mar 2003 00:12:08 -0500 Nothing personal, but there are problems with the advice quoted below. The archives of the "TowerTalk" reflector are a good resource, which will in turn point you to various authoritative sources, along with allowing you to read the discussions and different situations brought up. Start with a search on "towertalk single point ground", that you can begin using the search panel on the left of http://www.contesting.com There are many instances of small gauge wire being evaporated by a direct strike. #4 is the smallest regarded as direct strike survivable. Conservative installations use solid flat ribbon, or #2 or even 1/0. Spend a couple of entire evenings in the archives and get yourself up to date. 73, and may you never wonder what evaporated your wires, Guy, K2AV ----- Original Message ----- From: "Daniel L Brinneman" To: ; Sent: Sunday, March 23, 2003 10:50 PM Subject: Re: [Elecraft] Is there a "grounding" Elmer on line? -- snip -- +++++++++++++++++++ From: "Don Wilhelm" To: "Rosa" , Subject: Re: [Elecraft] Is there a "grounding" Elmer on line? Date: Mon, 24 Mar 2003 00:25:30 -0500 Charles, To start with, you need a path to ground for RF. That is ideally a short wide conductor from your ham rig location to a ground rod. Flat copper strap is the best - the wider, the better and the shorter the better - but be realistic given your physical shack location - we often must face compromises. Secondly, on the subject of lightning protecion, there was a good 2 (or 3) part article in QST a year or two ago that I thought was good - you might want to check it out - sorry but I don't have the specific issues at hand. For good lightning protection, the most important item is a grounding frame (or window) which is a large piece of copper that ALL the lines coming into the ham shack enters through - and your surge suppression devices are mounted on this plate. By ALL the lines, the meaning is truely ALL of them, antennas, telephone, Ethernet wiring, other computer wiring, and the shack's AC power. In addition to the grounding frame, you should have a buried ground system in addition to the ground rod outside the shack. An ideal location for this system is at the base of a tower or vertical antenna - then connect this system to the ground rod outside the shack. The QST article recommended a radial system of at least 8 wires each 80 feet long (I am using # 8 grounding wire and 1/2 inch rods for mine). Each radial has several DRIVEN ground rods, and the spacing between ground rods is twice the length of the rods. (i.e. each 80 foot ground wire needs 10 - 8 ft. ground rods.) In addition to the radial ground, start at the ground rod outside the hamshack, and bury a ground wire around the perimeter of your house - put an additional ground rod at each corner and connect it to the utility ground as well. The whole idea is to create enough conductors in the earth to quickly dissipate the energy in an electrical strike. Since there is a LARGE amount of energy in a lightning strike, there will be a finite time for that charge to dissipate - the better your ground system, the faster it will be, but remember that nothing is perfect - no matter how good your grounding system, remove the antennas from your equipment when a lightning storm is near and get yourself out of the hamshack!!! If your protection system is not close to the ideal, I recommend that you disconnect the antennas OUTSIDE and ground them when there is the possibility of a lightning storm nearby. In addition, if you have any lines running from your disconnect point into the shack area - do not leave them dsimply disconnected because they can pick up a charge too - ground them. You might consider bringing all the antennas into a box outside the shack and in that box have provisions to connect everything to ground. (this box would connect with a short copper strap to a driven ground rod. The gound wires should be either clamped to the ground rods above ground so you cxan inspect them periodically, or exothermaly welded to the ground rod if the connections must be buried. I did say driven ground rod - do not dig them in or use the 'copper pipe and water hose' technique we often hear about - these rods must be in the best electrical contact with the soil if they are do do their job, and loose soil will not provide good contact (watery soil is loose - it will shrink when it dries out and inland water is not a good conductor like seawater). If you can't get 8 foot rods down, use shorter ones and use more of them. A handy device for driving ground rods is the same device sold for driving metal fence posts - it is simply a piece of pipe closed on one end and handles on it so you can lift it and bring it down with good force. OK. I'm not an expert, but I am relating only what I have learned of lightning protection. Please check out some of the authoritive sources. I do know that we hams often cannot create an ideal grounding situation, so we put in the best that we can given our circumstances and take whatever additional precautions our limiting circumstances dictate. BE SAFE. 73, Don W3FPR ----- Original Message ----- Hello all, I am setting up my shack and have been confused about how to go about grounding the shack and the antennas. This weekend I put up a 20' tall (homebrew) guyed mast (top of mast is 38' off the ground and is about 5 feet above the tree line) on my roof that will secure one end of a 102' G5RV for the K2 (#3346) I am building and a Diamond HV7A on top for a Quad band Yaesu FT-8900R. I need to be comfortable with the grounding and lightening protection before I run the cables into the shack. One question is , can the same ground system be used for general grounding and for lighting protection? Can a #10 solid copper wire tied to the base of the mast and run to a 5/8" grounding rod protect from lighting? Can the same rod be used for the shack ground? I remember reading someplace (can not find it again) that 5 rods were required for lighting protection, if so how far apart should they be and what size wire would be used to connect them. I am kind of lost here, hope there is a grounding Elmer on the list. ++++++++++++++++++++ From: "Don Wilhelm" To: "Rosa" , Subject: Re: [Elecraft] Is there a "grounding" Elmer on line? Date: Mon, 24 Mar 2003 00:33:11 -0500 Sorry, my math was off in my recent posting - I meant each 80 foot ground wire needs 5 - 8 ft. ground rods (or 10 - 4 ft., etc.) IMHO shorter than 4 ft. would not be effective. 73, Don W3FPR +++++++++++++++++++ Date: Mon, 24 Mar 2003 22:24:49 +1200 From: Ron Willcocks To: Elecraft Reflector Subject: [Elecraft] Driving Earth Rods Hi all, as an aside to the posting about the type of earthing needed in an Amateur station, I have no great wisdom to offer as to the amount of earthing needed, but I can offer a tip for driving earth pegs in hard ground. (Earthing = the more the better......) As an Electrician of some years here, I once had to drive an earth mat for a commercial installation, and the ground type made the job impossible for conventional means. The solution was to use a "Kango" hammer. Take the tools out of the jaws and place the Kango hammer over a peg and hit the switch...the peg dissapears into rock hard ground faster than you could drive one in soft ground. Not sure if "Kango" is an American available tool, but it is an impact drill or driver. Ramset make the same sort of machine. I like to use pegs with "flags" on the top and bolt crimped connections onto them and bind them with "denso" tape.......a tape that is heavily inpregnated with grease. A connection done this way will last for years even when buried. Don't muck about with small gauge wiring between pegs. You want the least resistance posible. Be generous with the wire size. Myself, I have only two individual, connected pegs for my station, but then again we seldom have lightning here, the ground is volcanic and we have a generous rainfall.(too much so this Summer) The mileage will vary with location. Cheers......Ron ZL1TW +++++++++++++++++ From: N2EY at aol.com Date: Mon, 24 Mar 2003 08:27:06 EST Subject: Re: [Elecraft] Is there a "grounding" Elmer on line? To: info at CasaDeDomitila.com, Elecraft at mailman.qth.net In a message dated 3/23/03 8:55:38 PM Eastern Standard Time, info at CasaDeDomitila.com writes: > This weekend I put up a 20' tall (homebrew) guyed mast (top of mast is 38' > off the ground and is about 5 feet above the tree line) on my roof that will > secure one end of a 102' G5RV for the K2 (#3346) I am building and a Diamond > HV7A on top for a Quad band Yaesu FT-8900R. I need to be comfortable with > the grounding and lightening protection before I run the cables into the > shack. I assume this is a metal mast, made of TV masting or similar. > One question is , can the same ground system be used for general > grounding and for lighting protection? See the QST articles mentioned by another responder. Also check out the PolyPhaser website. > Can a #10 solid copper wire tied to > the base of the mast and run to a 5/8" grounding rod protect from lighting? I would not use anything lighter/smaller than #6 wire from the bottom of the mast to the ground rod. It is difficult to give general answers without knowing things like ground composition and conductivity. However, the following rules apply generally: - Lightning behaves like a very big RF pulse, so conductor surface area is very important (skin effect). - Anything that adds even a tiny bit of inductance or resistance to the ground path is a very bad thing. This includes things like sharp bends in a ground wire. - Soldered/crimped connections are OUT. Only substantial bolted or welded (including Cadweld) connections should be considered for lightning protection use. - There are lots of ways to get a ground connection, and they have to be tailored to your installation. - It is alaways a good idea to design the shack so that disconnecting the rig is easy. Visit your local Home Depot or equivalent and look around the electrical department. They have substantial ground rods (typically 8 or 10 feet long), #6 and heavier bare copper ground wire, and suitable clamps. Electrical supply houses are even better sources. But do not expect the salesfolks to be knowledgeable about your application, because they are primarily interested in service neutral grounding, not lightning protection. Driving ground rods can be made simple by the "Kango hammer" (jackhammer) method, if you have access, but if not, try a fence-post driver. This is a piece of heavy pipe with a cap on one end and handles on the sides. Slide it over the top of the ground rod and move briskly in an up-and-down motion to hammer the rod. Easier than trying to hit a wiggling ground rod end with a sledge. 73 de Jim, N2EY ++++++++++++++++++ To: info at CasaDeDomitila.com, Elecraft at mailman.qth.net Date: Mon, 24 Mar 2003 07:59:02 -0800 Subject: Re: [Elecraft] Is there a "grounding" Elmer on line? From: k6se at juno.com Generally, ground rods are good mainly for lightning protection. They are not good RF grounds unless they are at *least* 12 feet long. The best RF ground would be an extnsive counterpoise or radial system. When I was a new ham (W8DGP) in Detroit, I used a 6-foot ground rod for an RF ground and always had problems with RF in the shack. When I moved to Houston (W5RTQ), I implemented a ground system as outlined above and never had RF in the shack. My tower and antennas (which were at DC ground potential) there were hit by lightning on many ocassions and my radio equipment, although not disconnected, never suffered any damage. As KL7FRY in the Aleutians, RF in the shack was always prevalent when operating from my second-floor room where the best ground I had was the building's plumbing. Here at K6SE in the desert, lightning is not much of a problem. However, one of my towers was hit during a storm about 20 years ago with no damage incurred. RF in the shack is no a problem here on any band. Grounding here is similar to what I used in Houston. 73, de Earl, K6SE K2/100 #2622 +++++++++++++++++ From: "Stuart Rohre" To: , , "Daniel L Brinneman" Subject: Re: [Elecraft] Is there a "grounding" Elmer on line? Date: Mon, 24 Mar 2003 19:31:32 -0600 Daniel, grounds to rods should NEVER be soldered. Clamping or Cad welding are the only methods acceptable under National Electrical Code, and RF practice. Wetting down your ground rod, if a single rod, does not take care of the problem in dry areas. Most truly desert areas do not have enough conductive salts in the sandy earth to provide a good ground. In those areas, multiple conductors (wide and flat if possible for RF uses,) are used to form a crowfoot ground to spread charge from a strike over as wide an area as possible. The same problem in dry sandy areas is found in very wet tropical areas! Just having wet earth is NOT the answer. If it is rainy and tropical, along the equator- jungle areas for example, all the conductive salts leach out of the earth and wash away. In tropical Malaysia, it often took 5 or 10 ground rods driven to get an AC ground on a substation, or three phase building power entry. I have seen plasma from a nearby building strike travel 40 feet passing several grounding conductor down leads of a lightning rod system, to find one that had a more suitable low impedance before following the downlead into the earth. In dry rocky areas, lack of conductivity in the earth has lead our local utility to find by computer analysis that a minimum no. 10 wire 200 feet long, buried in a circumferential path around the building or substation will protect the station equivalent to a 5 ohm ground rod system. Larger wire can of course be used. This is very useful as the wire can be buried in a shallow trench, with the soil compacted after burial, if you cannot go deep and drive rods due to rock content. For Field use, the US Army has used many shorter rods, but this is for portable stations in temporary locations. No clear description of the assumed ground conductivity was given for that application. 73, Stuart K5KVH ++++++++++++++++++++ Reply-To: From: "Jerry Hancock" To: "Elecraft Reflector" Subject: RE: [Elecraft] Driving Earth Rods Date: Tue, 25 Mar 2003 15:12:59 -0800 I have a Kanga impact hammer and it works great for driving ground rods, less than a minute into the hardpack on the hill here. I think someone makes a tool to keep the end from mushrooming into the hammer. Jerry, KG6KGP +++++++++++++++++++++ Date: Wed, 26 Mar 2003 03:59:03 -0800 (PST) From: Leroy Buller Subject: RE: [Elecraft] Driving Earth Rods To: Elecraft Reflector Depending on the type of earth you have, you do not need to use a hammer at all with a ground rod. I have not used a hammer in years. Here is how I put in a ground rod....6 to 8 footers too. I dig a divit in the ground where I want the ground rod. If somebody has already talked about this forgive me for repeating. Get a gallon jug of water. Pour water in the divit. Now, start tamping the ground rod down with your hands. You might have to wear gloves and somtimes I put a vicegrips on the end of the ground rod to get a "grip." But, just keep putting water in the divit and tamping down the ground rod. Soon, you will have it all the way down. If you hit a rock, keep tamping and break the rock...shale...what have you. In the end you will be able to bring up the whole ground rod out of the hole...and put it back down again. You are done. Just put a connctor clamp on the ground rod and fill in the divit. Takes about 10 to 15 minutes. Lee - K0WA Jerry Hancock wrote:I have a Kanga impact hammer and it works great for driving ground rods, less than a minute into the hardpack on the hill here. I think someone makes a tool to keep the end from mushrooming into the hammer. Jerry, KG6KGP ++++++++++++++++++