I am in the initial stage of planning the pre-wiring for a new home. I have just spent several days going through the last several years of ASA postings, so I believe that I have a fair appreciation for the controversy within the group regarding panel grounding. However, unless I have missed it, I was unable to find any discussion of how lightning rod grounding should be handled, relative to panel grounding. This issue is of great concern for me because I live in a "lightning rich" region of the world.
In the trade for 40 years. In my experience it doesn't matter whether you ground the panel or not. This year has been a tough year for lightning in my area. I've had old and new panels go regardless if they had been grounded or not. About 12 of them this season alone. In years past, not so many as this year, but some were grounded, some were not. I usually ground a panel unless it's extremely difficult. When I ground them, it's to a cold water pipe ground, usually at the same point as the house ground or bonded to it.
In my experience, it seems that lightning has too many ways to get into an alarm panel for a ground to make much of a difference. All of the panels that got hit this season didn't have a mark on them but lots of magnetic contacts were welded together and had to be changed. I've had cases in the past where there were actual holes burned in the PC boards. This is not usually a high incident lightning area( usually one or two boards or none) , so it really hasn't paid to invest in lighting arrestors and surge protectors. You may want to look into installing these devices on your system since you do live in a known high incident area. Hell, if next season is the same as this, I'll have to look into it for my systems.
RHC: Sir, personally, I don't ground any of my panels. However, for those in rural areas, and other areas where lightning is a strong possibility, I install a device by Elk which grounds the AC and the phone line leading into the panel. Theoretically, this should guard the panel against damage, provided you have grounded this device properly to a common house ground water pipe etc.
I know they work well, because I once lost the same rural panel twice in one week until I installed this interface grounding device, and no problems since then.
At $28.50 dealer cost, it's pretty cheap insurance
Lightning arrestor grounding requirements differ somewhat from those for electrical system grounding. Under no circumstances should you ground a lightning arrestor system to your home's plumbing or electrical system. That can and will cause terrific damage if you get a hit. Rather, the ground should be connected to ground rods made for the purpose. They are 9 feet long x 1/2" diameter and made of a copper / steel alloy. The rods are driven 10 feet down. You can't just use any cable either. The stuff is braided copper or aluminum cable labeled for the purpose.
FWIW, I'm a strong advocate of DIY. However, lightning arrestor systems have stringent design requirements that must be met or you can actually increase the chance of lightning damage or injury. As such, I would advise you to consult an electrician or electrical engineer for more precise guidance than I (or most here) can offer.
Thank you for your candid assessment Jim, and for your concurrence Crash. This is beginning to get a bit scary for me. I can see that I'm going to have to get better educated than I am at present. I now live in a small town in northeast Thailand, in which neither security systems nor lightning protection are common. Much less so the likelihood of them being integrated into the same building. Based upon your above, and on earlier lightning related postings, I am beginning to worry whether constructing a lightning-resistant security system is even feasible here. I may well have to bring in an expert from Bangkok. But first...
Since both of you are certainly more expert than I, do you feel that a lightning arrestor/surge protected security system can be built, with a high degree of confidence that it will be effective? Or is lightning just so fickle that there isn't much hope?
Thank you for your reply Robert. I agree, that's pretty cheap insurance. Would you happen to have a web page, or a model number? (Don't trouble yourself if not handy -- I know how to use Google )
And for your well-taken note of precaution. Not to worry. I'm not going to take this one on without some precise guidance!
I would like your thoughts on this though. The house will be on a river bank, so I will be driving reinforced concrete piles for the foundation. Having observed them being driven before, there is a "boundary layer" of loose soil around at least the first few meters of the in-situ pile. What would you think about driving this 9 foot rod down into there, next to a pile, while that soil is still loose?
And if so, should I select a pile that is close to, or a ways away from, the house ground?
(Don't worry, I won't hold you (or anyone else) responsible !). I'm just trying to get a feeling for what makes sense.
for the alarm panel...or the house bond (your electrical contractor should be doing this)? imo not needed for the alarm panel...just go to nearest copper cold water pipe.
The location sounds pretty good. Damp soil near a river bank would be a better conductor than dry. I disagree with the other two gentlemen about grounding. Over the course of 24 years installing alarms I always grounded my panels (mostly Napco, not DSC). I also made certain that all services -- electrical, plumbing, CATV, telephone and gas line -- were connected to a single ground point. If you care to read additional comments on the subject, Google this newsgroup and the phrase "bonded ground." I and several others have discussed this a number of times.
Now for the catch. I understand the basics of lightning arrestor systems but I have not installed them so I'm not 100% certain if the lightning ground should be bonded to the same point. I've heard "experts" argue both ways. Speaking of experts, Jim and Bob are both experienced installers, as am I. But we disagree completely on grounding panels. In fact, Jim installs my favorite brand, Napco. He says don't ground. I say ground it. FWIW, Napco says you must ground the panel. Fun stuff, eh? :^)
Please indicate exactly where I said ..... don't ground a panel.
To help you out ...... the gist of my opinion is ............. in my experience, it doesn't seem to make a difference whether a panel is gounded or not. In 40 years of installing I've had both grounded and ungrounded panels damaged by lightning. Matter of fact, just had another one yesterday. Panel grounded to cold water pipe not more than
10 feet away. Damaged by lightning.
So, ........ are you saying that you never had a panel damaged by lightning?
RHC: Really, grounding panels and the science of lightning arrest are two separate although related topics. As you indicate, setting up workable lightning arrest systems for grounding are far more stringent and complicated than the relatively simple question of whether to ground panels or not.
I got into this area briefly when I set up a 40 foot tower on the roof of my home some years ago. With the need for 10 foot buried rods, and heavy cable from the tower to the grounding rod, it was evident that it has to be done correctly, or your tower can become a lightning rod of it's own. Since the average lightning bolt is about 17 billion volts, it seemed to me that anything I could do would be pretty puny in relation to stopping voltage such as this. A little further reading scared the crap out of me, and the end result was I took the tower down as far too dangerous to have up.
Well, several years later, lightning once again hit in our neighbourhood. It hit the huge tree between my home and the neighbours home, tore off all the bark for about 30 feet, split the tree down the middle (a tree about 4 feet thick I might add) and quite aribitrarily blew a six foot hole in the neighbour's roof rather than mine (it could have gone either way....) The house subsequently burned to the ground almost taking mine with it. Had I still had the tower up, I'm quite sure that my home would have gone up in smoke instead......
Lightning is scary shit !!! My suggestion to this gentleman is to hire a pro on that matter (or at least REALLY really know what you're doing....)
I "laugh out loud" at some of the answers I've been reading here over a grounded alarm panel.. (do any of you fine folks understand how lightening works?)
Think "Static" when doing a panel ground.
At best given the size of the MOV on the panel your only going to remove upwards of 1k volt for a micro second. Anything greater or longer and the MOV will explode. (ie.. the burnt pc boards or transistors/IC's as referenced earlier)
Granted if you have a large loop network and run next to ac feeds your more likely to induce voltage into your system and a grounded panel at that point will hurt not help.
But if your loops are well away from electrical feeds (keypad wiring as well) then a good earth ground will help. The key is "earth ground".
Now the electrical system is required by law to have its own ground rod. and the telephone d-mark box is required to be bonded to the electrical ground.
but a metal pipe that goes into the ground will also serve as a earth ground too. (I've found sometimes that a metal water pipe will have a better earth ground than the electrical ground rod.) (more surface area in the ground than the 10' rod.)
You can test to see if your loops have any static by attaching a volt/current meter from your loop to a good earth ground and read the voltage level.. in the current (series) mode you can tell if the loop is generating a voltage not just collecting a static voltage.
hope something above helps.
RHC: Really, grounding panels and the science of lightning arrest are two separate although related topics. As you indicate, setting up workable lightning arrest systems for grounding are far more stringent and complicated than the relatively simple question of whether to ground panels or not.
I got into this area briefly when I set up a 40 foot tower on the roof of my home some years ago. With the need for 10 foot buried rods, and heavy cable from the tower to the grounding rod, it was evident that it has to be done correctly, or your tower can become a lightning rod of it's own. Since the average lightning bolt is about 17 billion volts, it seemed to me that anything I could do would be pretty puny in relation to stopping voltage such as this. A little further reading scared the crap out of me, and the end result was I took the tower down as far too dangerous to have up.
Well, several years later, lightning once again hit in our neighbourhood. It hit the huge tree between my home and the neighbours home, tore off all the bark for about 30 feet, split the tree down the middle (a tree about 4 feet thick I might add) and quite aribitrarily blew a six foot hole in the neighbour's roof rather than mine (it could have gone either way....) The house subsequently burned to the ground almost taking mine with it. Had I still had the tower up, I'm quite sure that my home would have gone up in smoke instead......
Lightning is scary shit !!! My suggestion to this gentleman is to hire a pro on that matter (or at least REALLY really know what you're doing....)
The ground on the alarm panel is not intended to protect against a direct hit to the house. However, a bonded ground will protect against ground strike lightning or a nearby hit such as Bob C's tree. What you're trying to do is make certain that there is only one ground for all systems in the structure. This includes water pipes as well as all electrical and communication circuits.
When lightning hits the earth the energy spreads out like ripples on a pond. Current flows from the central point outward along the surface of the Earth. The ground is not as good a conductor as the wiring and plumbing pipes in your home. If you have two or more separate grounds in your home, lightning can enter through one and exit through another, destroying lots of stuff along the way. By bonding the grounds together you eliminate the potential between various grounds and reduce with it the propensity of the lightning to visit your alarm, your TV, etc.
What about lightning hitting an external bell box, would their not be a risk of the lightning setting fire to the bellbox cable, which works its way through the house to the panel.. Then it has to go through the panel (blowing that up) before it gets to the panels ground....
The bell box cable could have set the house on fire before that point through....
So? You say I don't recommend grounding panels, yet you can't point out where I said that. You say that you always used to have the guy who installed for you, 10 years ago, ( because you didn't have a license yourself, because you're a convicted felon) ..... ground the panels.
But you don't say whether you have had a panel disabled by a lightning hit. If you say you did, then it just re-inforces my opinion. If you say that you didn't, you know you'll be considered a liar ..... AGAIN.
So which is it? Oh .... I know. You just wont say anything ....... because you know you got caught again.
Connection to a water pipe may have numerous solder joints, sharp turns, and 40 feet to where pipe enters earth. Pipe may connect 60 Hz electricity to earth AND also be insufficiently conductive to a surge. Electricity with different characteristics means some conductors may be too long to conduct sufficiently.
Robert L Bass has provided facts that some electricians don't understand. Electricians are trained in characteristics of 60 Hz electricity. But those conductors behave differently for other electricity such as surges.
So that the same earth ground for 60 Hz AC is also conductive for other electricity, that ground should also be shorter (ie less than 10 feet), no splices and no sharp bends (which is why interior copper pipes make insufficient earthing), and single point ground. Destructive transient currents that get to earth without passing through a panel means no panel damage even during a direct strike.
If grounding wires are not separated from other wires, then a surge on that ground wire may be induces on all other wires. Again, not a problem when earthing AC electricity and a major problem when the same ground wire conducts a surge. An installer may believe the panel is grounded when panel ground is insufficient for surges.
Yes, an alarm panel and all incoming utilities wires require a short connection to single point ground. Also why a water pipe may be all but not ground. Anything else that might conduct a surge also needs an earthing connection where that surge would enter the building. An earthed surge would not conduct destructively though a panel. A properly earthed panel helps keep surge currents from obtaining other destructive paths through panels electronics..
Panels are damaged when that current pass through panel electronics. Earthing is about keeping surges from conducting through panel electronics. Every incoming utility wire also must make that same earthing connection. A ground connection that does not also include thoseother essential requirements (ie seperated from other non-ground wires which is why romex ground wire does not provide earthing).
A panel believed to be ground may not have been grounded sufficiently to conduct surges. Also other incoming utility wires must be earthed.
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