I recently had an electrician verify that I need a new grounding rod but before he does the work I wanted to get clear regarding the manner in which telephone, cable, roof mounted TV antenna, and water pipes should be grounded to the main service ground.
The rod will be planted a few feet from the house just opposite the inside service panel. Must the TV Antenna ground go all the way to the top of the rod or is it okay to split-bolt to the grounding wire at or just below ground level?
The main water pipe enters the house about 25 yards away from the grounding rod. Is it acceptable to ground the cold water pipe to the service ground from inside the house? In this case I would split-bolt to the service ground wire just before it goes through the basement wall.
My house is cabled for cable TV (although I don't currently subscribe). Where is the best (practical) place to ground the TV Cable? Split-Bolt again to service wire as it leaves basement?
Finally, what about Telephone system ground? Split-bolt as it leaves basement? Is this something the phone company must do (for demarcation reasons) and if so, are they gonna charge me for it?
Yes, the electrician answered these questions for me already, but my newsgroup search shows that answers vary and that sometimes the "pros" don't always do things 100% right, so that's why I've come back here to trusty old alt.home.repair.
Thomas D. Horne has accurately summarized important points as required by code. However effective earthing exceeds code. Every incoming utility must make a less than 10 foot connection where they all meet at your new central earth ground rod. That includes connections from cable ground block, from TV antenna and satellite dish wires before entering building, and ground wire from telco supplied surge protector in NID premise interface box. All earthing wires must also be direct (not via other wires, no sharp bends, no splices), and independent (not bundled with other non grounding wires and separate from all other earthing wires until they all meet at central earth ground). An old expression that says a better ground is not neat. No clean sharp bends. If an angled wire to earth ground is shorter, then angle the wire rather than make it look clean, sharp, and neat.
TV antenna is suppose to be earthed at shortest point. If TV antenna is earthed by a separate ground rod, then a buried solid copper wire (as sized according to code) must interconnect that separate rod with the main central earth ground rod.
If soil is non-conductive, than additional rods should be attached to that central earth ground rod. Central earth ground must be the best earthing point in the facility. Poorly conductive soil includes sand, loom, gravel, or soils bleached of ionic materials.
Some examples of how the earthing system should be reinstalled-
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Of course, the grounding system must comply with what Thomas D. Horne has posted since we earth for multiple reasons - one is demanded by cited code.
Water pipe is safety grounded - not necessarily earth grounded. Connection from water pipe must be to breaker box safety ground bar because that ground wire is to remove dangerous currents from the water pipe - a human safety function.
Thanks for the help Thomas D. Horne and everyone else. Sorry about the cut&paste manner in which I'm responding. I'm having newsgroup trouble. The guy helping me is a retired electrician. We're waiting on the gas company to label the gas lines before pounding the rod in the ground. Given your answers I can see you're being more techincal and accurate than he was, which is good! It's my job to go pick up the parts we'll need to do the job.
Thanks I understand, (assuming the EGC is just a fancy way of saying main-ground-wire-coming-from-the-service-panel-and-heading-toward-the-ground ing-rod.) I'll use a split bolt to ground the outside TV antenna ground conductor to the EGC after the EGC leaves the basement but before it reaches the ground rod.
Thanks for clearing that up. I'll bond the water pipe to the bus bar in the service panel, and then run the main ground EGC from that same bus bar to the ground rod. (Techincally, for the main EGC, I'll use the bolt-like attachement provided at the bottom of said bus bar) Because I'll be replacing the main EGC with fresh 4 gauge conductor, I'll probably just use some extra 4 gauge for the pipe to bus conductor as well.
Thanks to you and "w_tom", I see I may be referring to something different when I say TV cable ground. After the cable enters the house, it goes to a standard RCA splitter and it's from there that there is some kind of bleed off ground wire. It was this ground wire that I was referring to rather than something coming off a block outside the house. Right now the plan is to just split bolt the cable ground wire to the EGC just before it heads outside through the basement wall. I'll will have a look at the outside block for the TV Cable.
(assuming six feet means six meters as was corrected earlier)
The six meters is no problem as the telephone line enters the house right next to the service panel. However, I'm a little confused by what is meant by "Service's accessible grounding means". "Accessible" being the key word, I'm assuming you mean that Telco will ground to the EGC after exists the service panel, but before it heads outside through the basement wall.
Hmm. Assuming this section "IV" is referring to the EGC, are you saying that the main ground conductor must be insulated? And by insulated does that mean plastic wire covering? I thought I'd be safe with a bare solid copper
4 gauge wire? I must be reading this wrong...
Again, although this specifies 14 as the smallest, even 10 or 8 seems too small. Maybe this part of the code is not referring to the main EGC?
It's very kind of you to take the time to respond, Mr. Horne. If you'll indulge me in a little further clarification, I'd appreciate it all the more, but I'm already plenty grateful at this point.
Ground block is really nothing more than a connector that attached to CATV cable and that permits a 10 AWG ground wire to be connected. It is even sold in Home Depot with other CATV cable accessories. Best to put grounding block on cable outside building and as close to new ground rod as is possible. Make distance from CATV to ground rod shorter with minimal bends, etc. Yes that grounded RCA splitter accomplishes same for human safety and NEC reqirements. But transistor safety wants that connection to earth ground to be closer to central earth ground. Also an outside ground block to ground rod connection makes it easier to keep that ground wire separate from other non-grounded wires.
Telco provides a "Service's accessible grounding means" in a box called NID. Their 10 AWG earth ground wire connects their NID box mounted outside (so that it is accessible) to that earth ground rod. Some installers want to make that 10 AWG wire look neat. They will even 'split bolt' attach it to the breaker box ground wire. However better trained installers will run their ground wire directly to the top of that ground rod - as should be the CATV wire ground. All grounds should run indepenently until they all meet at central earth ground. This last requirement is not required in code but creates a more robust and effective earth ground.
As a rem> Thanks to you and "w_tom", I see I may be referring to something different
Thanks for your help Tom. I also explored the links you provided and found them helpful. In fact, part of the reason I started looking into this is because I have lost a modem. Although I have no reason to believe there have been multiple grounds in the past, I'll be sure everything goes to the same place before I'm done.
Hmm. Well, I checked and there's no ground whatsoever coming off the CATV line at the point it enters the house. I'd have to install a new one outside in order to run a ground line from the entrance point, and that side of the house is the exact opposite of where I plan to put the ground rod. The CATV comes from the street to the top of my house and then runs down before meeting a splitter and entering the house. Becuase I don't currently subscribe to Cable (and don't plan to), I think I'll just disconnect the cable so that it never even enters the house and then I'll just forget about grounding it. Is there any reason why this would be unsafe or cause electrical trouble?
Well, the Network Interface Box I have now is really old and in bad shape. There's no NID or block or anything outside of house. The line comes straight in. (I'll spare you the details, but let me just say that I'll be calling Telco as soon as I get my electrical troubles in order.) Even so, I'm glad you mentioned it. I can leave the top of the ground rod exposed and that way Telco can have the option to run a conductor straight to it, rather than using the split-bolt method. At this point I have no idea what they will do or if they will even install an outside NID. One way or the other, the current telephone junction box needs replacing.
If I'm following your line of thinking, then wouldn't it be slightly better to run the TV Antenna ground straight to the grounding rod tip as opposed to split-bolting it to the main ground (coming from the service panel and heading towards the rod)?
Oh, an in case I don't hear from Thomas Horne, is bare 4 gauge copper conductor appropriate for grounding the service panel to the grounding rod, or must it be insulated with plastic? (I was just at Lowes and the "x-electrician" there says I only need the bare wire)
Thanks. Sorry for being so caught up in the details. I really want to do this right and do it safe, and I'm not getting the same answers from the local "Pros".
Once again I have typed too fast. The abbreviation I meant to use is GEC.
That primary telephone protector should be located outside the home. That will keep much of the surge and spike energy outside of your home.
That part of the code CEOs not refer to the Electrical Service GEC but rather to the Communications Grounding Conductor. This conductor bonds the communications protector to the GEC or the other accessible grounding means. W_Tom's suggestion to run the communications grounding conductor to the Ground rod itself will cause a few challenges. One is that conductors smaller than #6 must have protection from physical damage. Lawn mowers, edge trimmers, & weed eaters expose GECs to severe physical damage so any conductor that is run within reach of such equipment must be number four or be run in protective raceway. If the conductors would run adjacent to each other anyway than a split bolt or saddle clamp would be just as effective.
Did the electrician say you need a NEW grounding rod or a SECOND grounding rod? The reason that I am asking is that a local electrical inspector just told me that the "new electrical code" now calls for TWO grounding rods to be installed 6 feet apart -- instead of just one grounding rod. He said one continuous #6 grounding wire would go from one rod to the next rod 6 feet away (and looped around it) and then to the neutral block on the electric panel box.
I know nothing about how all of this works and will probably just have an electrician do it. But, when I saw your subject line, I figured I'd pass on what I was just told in case it helps.
Thanks to both Toms (and everyone else) for all the clarifications. Words are cheap, but I really do appreciate the help. I'm ready to let the Electrician lead the way, but now I can make sure all is on the up and up.
Of course, knowing me, there's one last detail. Power comes into my house to a main breaker box, then goes out to a separate modern service panel. The main breaker box is nothing more than a 100 amp breaker with no bus bars or anything like that. (Sorry if that was obvious). Power goes through this main breaker and over to a separate modern service panel. Likewise, a
4 gague copper ground conductor leaves this main breaker box and goes out to the modern service panel.
Currently, the GEC leaves from the main breaker box and goes out through the basement wall to earth ground.
If I understand correctly, from what I've learned here, the new setup should have the GEC going from the ground bar of the modern service panel out through the wall to the grounding rod, instead of the GEC coming from the initial main breaker box. Is that correct?
(If the correct method is to run the GEC from the initial breaker box, then does that mean the water pipe ground conductor should also be grounded to this same box as opposed to using the modern service panel's ground bus bar?)
And with that, I'll let this long thread putter out. Thanks for sticking with me and my poor newserver access. lol.
Just to be clear, there is a small 4 inch bar that accepts the incoming ground and allows for the copper conductor to leave the box to go to the earth ground and another to go to the modern service panel. I just meant there's no modern style bus bar and no room for additional circuits or anything like that.
There is no such thing as a "central earth ground" unless only _one_ grounding electrode is used.....a very poor practice in itself (with the possible exception of a metal well casing)....much better to have _multiple_ grounding electrodes bonded together. All grounding electrodes are bonded together to form a _single_ grounding electode _system_. The ground rod that is being installed is merely a _supplement_ to the main grounding electrode.......in this case the metal water pipe. Not a good idea to try to dump all that on a single ground rod.......a single ground rod will in fact become a choke to lightning trying to get into the ground. That single ground rod should be supplemented by at least another ground rod 6 feet away (or use a delta ground), or a ground ring can be installed with a minimum #2.....and catch the cable TV while you are at it.
The basic idea is too run an unbroken GEC from the main panel to the underground water pipe (min. #4) and suppliment that with a ground rod (or two). Then bond all systems together. The idea is that when all the systems are bonded together, ALL will come up to the same voltage (can be ma ny thousands of volts), thus _not_ allowing a destructive current flow in equipment served from different systems....like a modem. Don't forget to jumper around the water meter and bond the hot water.
Bottom line, electric system grounding is a very misunderstood subject and needs to be done by people who know and care about how to install it.
You still have your inside metal gas line to deal with.......you should call your gas co. to see if they allow an (inside) connection to the electric grounding system as required by NEC.
I hope that after going through all that trouble that you are also going to install a lightning arrestor at the electric meter or service panel. Then use a decent point of use surge protector for the computer that has provision for power _and_ phone....cable too if you ever use a cable modem.
Also, since you said that you have a subpanel in another thread, you should check to see that the subpanel is fed from the main panel with a _4_ wire feeder (2 hots, neutral, equipment ground).
I guess I could be convinced to install 2 rods. I'm doing the work to install the first.
If I plant the ground rods just outside the wall of my service panel, I'd have to dig 20 yards over and eight feet down to bring the #4 to the water pipe. If I run #4 from the ground bar to the water pipe from inside the house and then do two ground rods, won't that be enough?
If I bond the hot water pipe, I'm guessing I would do it the same way as the cold (from the inside).
What do you mean by "jumping around" the water meter?
Don't get me wrong. I trust the advice here or I wouldn't be here. But here's the bottom line for me. Whatever electrician the previous home owner hired didn't do the job right, the electrician I hired to inspect the home before I bought it didn't see the problems, and the electrician I'm currently paying to fix things now is contradicting the advice I'm getting here. I guess I could go to the yellow pages again, but at this point I if I don't know what "right" is, I don't think I'll ever have peace of mind over what work is finally done.
I had the gas guy out ther other day. Although the pipes I see are metal, he said the lines underground were plastic, but I'll make the call to make sure.
I'll look into that, but it seems like overkill at this point.
I have a $35 surge protector I use for electrical and telephone.
Power enters the house in the form of two hot conductors going to the single
100A breaker box and then exit the box, going to the modern service panel. The neutral conductor coming into the house goes to a short metal "bar" which is bonded to the box itself, and then it also leaves the box and goes to the neutral bar of the modern service panel. From inside the 100A breaker box, from that same short metal "bar" there are also two 4 gague bare copper conductors that leave the box. Currenly, one leaves the box and goes through the basement wall and out to earth ground. The other copper conductor leaves the box and goes to the ground bus bar of the modern service panel.
Sorry, I wasn't clear when I said "panel". You must connect the mandatory GEC at the 100A small disconnect box (or other connected service equipment). You may NOT run the mandatory GEC from your modern panel, because it is not part of your service equipment. It sounds like you want to ground from the proper place, which is at the service equipment, which is where neutral and ground are the same wire or bus.
In your other post, you mentioned a water pipe ground. We just went through this in "Ground Rod Questions - summary". To summarize, if you have a metal water pipe that is in contact with the earth for 10 feet or more, you MUST use it as your primary grounding electrode. You must connect to it within 5' from where the water pipe enters the house. This wire must be unspliced from the water pipe to the service equipment neutral lug or wire. If you have a water pipe ground, in most cases you must install a second electrode which is usually a single rod. You shouldn't need two rods, but if you replace your water pipe with plastic, then you do need two. Putting two in now prepares you for the future and improves your grounding electrode system. Additional rods must be at least 6' from any other rods in the same grounding system. Alternatively, if you switch to plastic water service, leave the old pipe buried in the ground and use that as your second electrode (if you can get an unspliced wire to it).
Jumping around the meter means clamping a #4 wire between the input and output sides of the meter. You can't be sure if a meter is conductive, so you must put a jumper around it. This only applies if the meter at your house between the buried water pipe and your inside pipes. My water meter is at the street, and you don't jumper those.
WOuld "MUST" still apply if the proper attachment location to the water pipe is > 35 feet from the panel ? Or would the code then prefer two grounding rods ?
Pardon me for thread jumping... I need to do this too.
What's the theory behind getting outside the drip line ? Just avoiding the extra moisture on the connections ? I'd think it would actually help the conductivity to the rod.
Also, are you strong on the "two rod" approach even with the a water pipe serving as one leg already ?
Again, theory question... why does the _hot_ water pipe meed to be part of the ground system ? I'm not questioning doing it, sounds easy enough to jumper, I'm just wondering why it's needed.
Is there a particular model you recommend ? I have looked over sites like Intermatic
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but they have TVSS units, surge arrestor units, etc. Even if I concentrate on the surge arrestors units, they have 120/240, 240/120, two pole, three pole, etc. I do plan to have an electrician do the work with this part but I have a feeling he might not know much more about the _units_ themselves and how the manufacturers compare than I do.
I have only a service panel with a main breaker... do I want a "service entrance" unit or a "panel board" unit" ?
Attitude of code is that water pipe is not sufficient as the primary or reliable earth ground connection. A separate ground rod (or something equivalent) is required even if water pipe earthing is available. Other incoming utilities will use that ground rod as central earth ground; not water pipe. Connection to water pipe is supplemental earthing to new installations. Connection to one or multiple earth ground rod (or whatever else you use for the earthing system), all at same point, becomes single point earth ground. Everything earths to multiple ground rods at same point. Even the television aerial should make some connection to that single point earth ground before entering a building even though the aerial itself has a direct connection to a separate ground rod
- to fully optimize earthing for surge protection. These exceed code requirements to make a superior protection 'system'.
That connection to water pipe is primarily to remove currents from pipes - for human safety. Same safety reason is why hot water pipes would also be grounded to panel ground. If water pipe is also being used
Code requires a second ground rod if the first does not measure less than 25 ohms. If second rod does not make less than 25 ohms, then a third rod is not required - by code. Code is not optimized for effective surge protection. If earth is so non-conductive as to not supply less than 25 ohms, then a more serious earthing system should be installed such as halo ground, plate electrodes, or Ufer grounding. One rod will make a minimally sufficient earthing connection in most cases. Two rods will make every 'whole house' protector more effective. The most important component in a surge protection 'system' is its earth ground. Earthing and distance of wire to that central earth ground will often be the 'choke point' for system effectiveness. Additional money spent on surge protection often is best spent on enhancing the single point earth ground.
Code does not define how that earth resistance is to be measured. Most locations will get less than 25 ohms with only one ground rod. However, considering how important that earthing system is also for transistor safety, then a second rod is cheap insurance. Utility will install massive grounding networks underneath a substation and still obtain resistance on the order of 2 ohms. The first rod will lower resistance. Every additional rod will provide less improvement.
That's just not true, Tom. An underground metal water pipe is indeed a very good grounding electrode. Why then does NEC (2002)Section 250.30(4) _specifically_ require that an underground water pipe (and/or structural steel) be used as the primary grounding electrode? Why then does the NEC allow _made_ grounding electrodes (ground rods,etc) ONLY when a water ground or structural steel is not available?
The ONLY reason that a ground rod is required by NEC to _supplement_ a water ground is because of the distinct possibility that the metal water pipe may be replaced by the water co.......leaving the system with no ground at all. While a single ground rod is not the best ground, it's _certainly_ better than none at all.
Again, just not true. The other utilities will grab on to any ground that they can find. The NEC indeed requires that the electric service have provision for same......even if it's just a bare #6 hanging out of the bottom of the electric panel. There is not such thing as "central earth ground" as you describe it.......and is in fact ludicrous to think that a single ground rod is the "central earth ground." A single ground rod is about the worst possible grounding electrode permitted by NEC.......it just can't dissipate near as many electrons in a given time time as compared to a water ground, ufer, structural steel, or a ground ring. In fact, it if you try to dump all that on a single ground rod it will become a choke. That's why, when installing a single ground rod (only) as a supplement to a better ground, such as a water ground, that the wire to the an _individual_ ground rod, REGARDLESS of the size of service only needs to be a #6 wire (per NEC)........the ground rod just won't dissipate any more electrons than the #6 can handle.
No, it is _not_. It is the _primary_ grounding electrode, if available. Problem is, these days plastic pipe is used. Any interior metal water piping is connected to the neutral busbar to clear ground-faults should they become energized.
No, connection (bonding) of multiple grounding electrodes forms a _single_ grounding electrode _system_. If you want to call something "a central earth ground" the service entrance neutral busbar would be a more accurate description. Even microwave towers have at least 100 or more Cad Welds bonding every possible piece of metal and ground together. Where is the "central earth ground" on that? There is _no_ single grounding point. If you're referring to a single grounding connection point on a micowave tower before all cables enter the building, then the corresponding single grounding connection point on a house is basically the service equipment neutral busbar. And if you want to start rambling about differential and common mode surges......then you should at least recognize that, indeed, the service entrance neutral busbar is _where_ the neutral and the equipment grounding conductors are bonded together.......and _think_ about _that_ before you respond.
Yeah, like the neutral busbar in the service equipment! It's not a radar station, Tom.
No, the primary purpose of a metal underground water pipe is to ground the electric system.
THAT, I will concur. With more and more plastic being used these days, it's very difficult to obtain a decent electric system ground. It would not be much of a hardship on electrical contractors for the NEC to require a Ufer (concrete-encased) grounding system......they just need to be there before the concrete gets poured. Make it a requirement to get the OK to pour, just like bug spray is required in most areas.
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