Grounding System

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nayr

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I erected 2 antennas on my roof on-top of 10ft galvanized poles bolted to sewer vent, guy wires have held strong this week with gusts up to 70mph.

My house is old and the basement is full of copper, even my sewer pipes are giant copper pipes. I am using the water pipes as a grounding bus. There are 3 small basement windows on 3 different sides of the house with the water main running past them. Each window well I pounded in an 8ft grounding rod and bonded it to the water main with 4ga solid copper wire. Sanded the water pipe fresh at each junction. The window well on the back side of the house is feet away from the power main, I bonded the rod in this window directly to the rod my circuit box is using again with 4ga wire.

My Radios are mounted in a Steel Server Cabinet with a solid copper stick running across the back rails of each rack and bonded together. The grounding rail is bonded to water pipe few feet away with 4ga solid copper wire. The window well in my server room I mounted a 3ft piece of nickel coated angle iron directly to the grounding rod with stainless u-bolts... I can only afford gas arrestors at this time but they are bolted directly to the angle iron. The feed line enters my server room through the same window.

In the laundry room I bonded the water main to the sewer pipes (masts are on sewer remember) with 4ga wire. I have a swamp cooler on the roof already grounded to the water main in the basement with 4ga, I need some more wire but I plan on bonding the masts directly to the swamp cooler ground on the roof.

Is there anything I am missing/doing wrong? I read up alot but its all so complex.. I tried to make nice gradual turns and bends as much as possible.. I dont know how wise it is to use my water mains, I assume it'll work fine with alot of paths to ground but it does take sharp turns which isint good.

It'd take several hundred feet of copper to directly bond the masts to a grounding rod; would it be worth it?

Eventually I'd like to put up a 40' self supporting mast outside my server room, perhaps then I can bond everything externally then with an array of rods going around the house.

I'd like to be able to survive a modest lightning strike; I do have home-owners insurance but they wont cover the hundreds of hours I have into work being done down there. I am not made of copper however.

*edit*
Radio Power supply on a pair of 30A APC Battery UPS, my electrical box is too old for a whole house surge protector but I might be able to put one in the basement subpanel. (Which can only be grounded to power main)

Thanks,
-R
 
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ampulman

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Perhaps an expert will comment on whether the perimeter ground rods should be bonded to the powerline ground at the service entrance and forget about the water mains.
 

LtDoc

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My first post didn't 'take' for some reason so I'll try again.

I'm not an expert so don't take this as such.
No matter what you do there's no -sure- way to survive a lightning strike without damage of some kind. Having said that, your system is definitely more extensive than most and should have a better chance than most. I would definitely recommend taking a look at the National Electrical Code about grounding. I also would agree that depending on those large copper water pipes going further than the outside of your foundation may not be the best idea in the world. Who knows just how far they extend?
connecting the antenna supports on the roof to the ground system is a nice idea and I think you should do it.
Just keep in mind that those ground cables are going to be subject to humongus current flows no matter if it's a 'large' strike or a 'small' one (how do you tell the difference??).
Good luck.
- 'Doc
 

nayr

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yeah the idea is to control the damage, keep it away from my equipment. However, Radio Towers take direct hits daily while broadcasting with no damage, the transmission will go dead while the strike is happening but once the breakers auto-reset there back online w/no repair.. Ive heard it happen on-air a few times but I have to assume those setups have thousands of dollars in giant copper straps and bars chemically bonded and running away from there facilities in a nice sized array... not to mention top of the line arrestors/surge deflectors, feed-line and antennas.

one of the reasons for using the water main was doing a perimeter array directly connected to power mains is not possible at this time.. too much landscaping in the way. My server room and the power mains are pretty far away and this was the only way I could come up with to bond everything together without ripping out the yard or making giant detours.. I figure it'd take 100ft of wire and ~7 more grounding rods to directly connect the rod in my server room window to the grounding rod the power main uses.

I guess a big strike would result in alot of welded metal and a very sad insurance agent... a modest strike would blow my antennas up but should find multiple paths to earth with much less resistance than going through my hardware.

I guess the best thing to do is unplug the antenna durring a lightning storm; which I will try to do.. but I operate a repeater and I dont want to take it down every time I am away from the house for a while.. If I go on vacation and a storm rolls in how do I unplug the antennas? Hrmm, sounds like a interesting ardruino project tho :)

Thanks, yeah I guess I should be satisfied.. I think I got all the basic stuff taken care of and in the 4 years at this location I have only heard a couple of lightning hits within a mile of here...
 

westom1

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one of the reasons for using the water main was doing a perimeter array directly connected to power mains is not possible at this time.. too much landscaping in the way. My server room and the power mains are pretty far away and this was the only way I could come up with to bond everything together without ripping out the yard or making giant detours...
You have therefore setup your house for transient damage. The term single point earth ground is critical.

NEC requires that the water pipes are bonded to the power line ground. That is essential for human safety. Also, water pipe earth ground is the only electrode that is insufficient. The NEC lists five other earth electrodes. All others are sufficient. Any one of those other earthing electrodes must also exist if a water pipe does earthing.

Those requirements are only for human safety. You are asking about transistor safety. The requirements are even more extensive. Transistor safety means earthing must both meet and exceed NEC requirements for human safety.

Critical to transient protection is impedance. For example, water pipes with sharp bends and solder joints have excessive impedance. Impedance is why a protector must be connected to earth by a conductor that is short (ie 'less than 10 feet'), no sharp bends, not inside metallic conduit, and separated from other non-grounding wires.

All protection systems only have one component - single point earth ground. Any wire that enter a building must connect low impedance (ie 'less than 10 feet') to that common earthing electrode. Even underground wires.

If AC has three wires, then all three must connect that short to earth. AC power is not possible if all three connect directly. So all but one make that short connection via a protector. A protector is only a connecting device. Protection means a wire to earth. Or a protector to earth. But in every case, the transient current must connect to single point ground.

Same rule applies to telephone wires. Telephones already have a superior protector. Also only as effective as an earth ground. A homeowner is responsible for providing that earth ground. Then a telcos NID can connect low impedance to the same ground used by AC electric, cable TV, and any other incoming wire.

A utility demonstrates the good, bad, and ugly (preferred, wrong, and right) solutions at:
Tech Tip 08 - Indiana Business-Duke Energy

An example of why this is important. Lightning strikes a tree maybe 30 feet from a cow. So the cow is struck directly. Lightning is a connect from a cloud three miles up to earthborne charges maybe four miles away via earth. The shortest electrical path is also up the cow's hind legs and down its fore legs. Cow was in the path of a direct lightning strike due to no single point earth ground.

Had that cow been encircled by a bare copper wire, then all four legs connected to the same single point earth ground. You have created the same problem. A better connection to earthborne charges is a current running through your house and its appliances.

Protection is always about where that current conducts. The cow is protected when current need not enter and pass through its body. Homes are protected using same concepts. Single point earth ground is critical. If using multiple grounds, then protection is compromised.
 

nayr

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ok well now I am more confused, my feed lines have there own ground rod, my electrical has its own ground rod. As I understand I need to bond the two together so there impedance match. I used a 3rd ground rod and my copper piping to connect them through the house (not ideal yes).. I understand having multiple isolated paths is bad mojo, the path with least resistance is how the current will flow.. if that means through your equipment and to its isolated ground point. I thought the point of me connecting all these grounding points together was so they acted as a single ground with shorter paths.

I was going to bond my server cabinets directly to the ground rod for the feed-lines but then I figured with enough voltage coming down feed-line they would go through my server cabinets to reach the main power ground.. so I opted to ground the cabinets to the water main along with all the grounding rods.

So how the hell do you ground your antennas if your feedlines dont enter within 10ft of your power mains? My water pipes are not used as the primary house ground.
 
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prcguy

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Looks like the OP has fairly substantial grounding and more than most but its very difficult to take a home electrical system and make it direct hit proof like mountain repeater sites that were literally designed from the ground up. There are books available from Polyphaser and others that will tell you how to build a proper lightning ground system at a level you will not find on a hobby forum like this.

One of the goals for lightning strike survival is keeping the grounds on all equipment at the site or your house at the same potential and that's where a central or star grounding system as someone else mentioned can benefit.

During a strike everything will be elevated perhaps thousands of volts above the normal ground potential but a properly designed system will have all equipment at or very near the same potential, even though its all very high during the strike. Its the difference in potential between grounds that can destroy electrical equipment in your house and that's where bonding all ground rods to the electrical system come into play. But you may not be able to achieve the required level of protection in a home installation.

The building I work in (which is not on a mountain top) originally had 75, 8ft long ground rods, with the tops buried 4ft underground spaced around the building parameter and cad welded to a 500MCM cable (about 3/4" dia stranded copper) buried 4ft underground in a ring around the entire building. That costs a lot of $$.

After many upgrades over the years I lost count of the ground rods and ground rings of 500MCM cable around our various antenna foundations but there must be at least 150 or more 8ft rods, all bonded together and to the main electrical star ground system inside the building. This is in an area with very little lightning but its the kind of precaution you need to protect expensive equipment from damage.

As a coincidence, last weekend I replaced an antenna on a major mountain top repeater site in So Cal where the top of the antenna was blown apart by a lightning hit but no equipment was damaged inside. This is the second antenna on this system that was damaged by lightning in the last 2yrs so it is possible to build a ground system that will take direct hits and keep on working.

Unfortunately the cost to build a strike proof ground system is well beyond what most of us can afford at home, even if your radio room and house electrical system happen to be laid out for a central or star ground. Usually the radios and antennas are on the other side of the house from the electrical entry point or the radios are on a 2nd floor, etc. In that case or in all cases you should follow NEC Article 810 at the minimum for grounding and disconnect your antennas when lightning is a possibility.
prcguy



ok well now I am more confused, my feed lines have there own ground rod, my electrical has its own ground rod. As I understand I need to bond the two together so there impedance match. I used a 3rd ground rod and my copper piping to connect them through the house (not ideal yes).. I understand having multiple isolated paths is bad mojo, the path with least resistance is how the current will flow.. if that means through your equipment and to its isolated ground point. I thought the point of me connecting all these grounding points together was so they acted as a single ground with shorter paths.

I was going to bond my server cabinets directly to the ground rod for the feed-lines but then I figured with enough voltage coming down feed-line they would go through my server cabinets to reach the main power ground.. so I opted to ground the cabinets to the water main along with all the grounding rods.

So how the hell do you ground your antennas if your feedlines dont enter within 10ft of your power mains? My water pipes are not used as the primary house ground.
 
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westom1

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As I understand I need to bond the two together so there impedance match. ...I was going to bond my server cabinets directly to the ground rod for the feed-lines but then I figured with enough voltage coming down feed-line they would go through my server cabinets to reach the main power ground..
You are assuming things not found in that post. For example, the term 'low impedance' and 'impedance matching' define two completely different concepts. Both just happen to share a same noun -impedance.

Grounding a cabinet can also make damage easier.

The post describes something completely new. It will not make sense until maybe after the third reread.

First, it is electricity. Define one incoming path. And another outgoing path. If that path passes through appliances (ie your cabinet), then damage is likely. Never stop a surge current. Connect it on a low impedance path from a cloud to earthed charges. That current is simultaneous everywhere in that path. If incoming on something (electronics, a protector), then the same current is also outgoing. Nothing stops that current.

Franklin demonstrated this in 1752. Connect that current on a path that is not destructive. Not inside a building or a cow. If anything (even a pipe) inside a building carries that current, then ineffective protection exists. Protection is always about a current path from cloud to distant charges that stays outside a building (or a cow).

Either that current is earthed harmlessly outside. Or current goes hunting destructively for earth via appliances. Earthing a cabinet may give that current a destructive path. Cabinet must be safety grounded for human safety. Earthing anything inside a house is a code violation and does nothing for transient protection.

Low impedance is defined by a shorter wire; not by a thicker wire. Higher impedance is created by sharp wire bends and splices. Impedance matching is not about either. Water mains are also not a superior ground conductor. Code defines it insufficient even for human safety.

It sounds like you have no choice. A solid and bare copper wire must be buried between all earth ground electrodes as defined by the National Electrical Code (that defines wire thickness and depth). Trace a path from each wire in every incoming cable (even underground) to single point ground. Telephone has two wires. Each must have a low impedance path to earth. AC electric - maybe three wires. Each must connect low impedance to earth

In each case, a path from cloud to distant charges must not be hunting inside a building. That solution was well understood even 100 years ago. Also defined in two articles the QST Magazine in 2002 entitled "Lightning Protection for the Amateur Radio Station". If concepts are new, then those articles will also require multiple rereads.
 

westom1

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So how the hell do you ground your antennas if your feedlines dont enter within 10ft of your power mains?
An antenna may be a separate structure. Each structure (antenna or satellite dish) must have its own single point earth ground. A professional's application note is entitled "The Need for Coordinated Protection":
http://www.erico.com/public/library/fep/technotes/tncr002.pdf

Each structure has its own single point ground. Any incoming wire (even underground) connects to that ground before entering. Any wire that enters an antenna first gets earthed. To make both single point grounds better, an earthed ground wire interconnects both grounds.

Same applies when interconnecting buildings. If either violate the 'incoming earthed wire' rule, then a lightning strike to one building may be a lightning rod connected to electronics inside the other.

Two ten foot earth ground rods are major earthing. Sufficient for most locales. Geology is another factor.

Additional earthing adds less improvement. Some facilities will spend massively ($thousands) to add a little more improvement. Because earthing is critical to protection. Most buildings have massive protection from lighting by creating a single point earth ground using two ten foot ground rods.

Some facilities may need more due to geology. Ufer grounds were pioneered in munitions dumps so that direct lightning strikes cause no surge and explosion. A radio station demonstrates what was necessary to have protection on a rocky mountainside:
UFER grounding system

Protection is always defined by a transient’s electrical path. Protection means that path never enters a building.
 

nayr

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thanks for the sound advice, I guess the biggest point i should accept is my house was never designed to take a big hit like that... I'll do my best and see what happens. My house sits on a ridge at a fairly high altitude, before I started raising masts I was lower than everyone around me, but now my antennas are pretty high and if I can get the city to gimme a permit for a 40ft mast im going to go for it and other than a few big office buildings that would be above the tree & roof lines by a bit.

I find it kinda startling that I am the only one to go through stuff like this when I see shacks with alot more money invested in em. When I was a kid took all my radios and electronics to my grandpas home-office down the street while we were remodeling, mainly to keep dust off and so I could still use em over summer with air conditioning.. Sadly there telephone pole got hit, the lightning came in to the power system through my modem and then toasted everything else on the same power strip.. even tho they were all off. Since then I've always been paranoid because well my grandpa's insurance didnt replace all my gear and It took years to recover... grandma and grandpa just lost a few alarm clocks and cordless phones.

Since then Ive lost non-protected devices and a few apc units from close strikes but never any of my protected equipment.
-R
 
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ampulman

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After reading this post I did a little Googling n=and came across this article: What are the NEC grounding requirements for satellite dishes?

I too am in the design phase of an exterior ant. and plan on following the above to the best of my wallets ability:)

Hopefully it will help

Nick
I wonder how many of you with dishes on the roof can say that the NEC guidelines have been followed during installation.

My neighbor, across the street, has his dish installed on the opposite side of the house as the service entrance. I estimate that it would take 50 feet or so of wire and some ground rods to bond to the service ground.

I don't think this has been done.

Amp
 

LtDoc

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I don't have a cow either. I wonder if soup bones would work, if there's enough of them?
I've never heard of a dog or cat being struck by lightning. I wonder if... Naw, who want's herd of cats?
- 'Doc
 

westom1

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My neighbor, across the street, has his dish installed on the opposite side of the house as the service entrance. I estimate that it would take 50 feet or so of wire and some ground rods to bond to the service ground.
If a connection to ground is 50 feet, then an earth ground does not exist. Too long. Would even violate the NEC.

The NEC only defines human safety. Transistor safety is about exceeding those same requirements. That ground wire also must be low impedance (ie 'less than 10 feet', no sharp bends, etc).

A utility suggests a kludge when installers or linemen do not know basic electrical concepts. Demonstrated are good, bad, and ugly (preferred, wrong, and right) solutions:
Tech Tip 08 - Indiana Business-Duke Energy

If nothing can protect from direct lightning strikes, then TV and FM radio stations in NYC are destroyed when lightning strikes the Empire State Building 23 times annually? Really? We earth so that even direct lightning strikes cause no damage. If damage results, an investigation begins by locating the human mistake. Usually by inspecting what makes even direct lightning strikes irrelevant. Earth ground.

Commercial broadcast stations, cell phone towers, wires entering telephone switching centers, high voltage power lines, and even munitions dumps must suffer direct lightning strikes without damage. Either that direct strike has the shortest (low impedance) connection to single point earth ground. Or an installation defect may result in damage. NEC is exceeded for transistor protection.
 

thomast77

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I would not ground to water pipes. IMO that is asking for trouble. You are inviting the lightening into your home. Someone could get hurt just being close to the pipes or in the shower or something.

The proper way is to ground your equipment to a bus and run preferably copper strap the most direct route outside of your house to a ground rod. Your coax shield should also be grounded to the same Ground rod. Then you have to run preferably copper strap (but 4 gauge Copper wire will work) to the power mains ground rod using ground rods every 9 feet or so. I would also recommend you cadweld the strap or copper wire to the ground rods bury it and forget about it. If you use clamps you will have to dig them up several times a year to make sure they still have a good connection. Also if you are in an older home and the electric mains is grounded to the water pipe. I would recommend you drive a ground rod and connect the mains to that instead of the water pipe. Copper Strap is recommended because of the "Skin Effect". Most current travels along the outside of the wire or strap ("Skin Effect"). So because the strap has a much larger surface area it has much less resistance to ground. This is the proper way to ground your system.
 
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