| YAGT: Grounding outside antenna without a service ground Yet another grounding thread! I've been reading a lot of the existing threads, but can't find any that cover this scenario.
I have an antenna mounted 12' high on a wooden pole, located about 80' from the house that's powering the radio. I already have CAT5 in the ground to the exterior of the house, but I don't know how to do the surge protection before I penetrate the house. There is no utility ground rod for the building; the house's breaker panel has a neutral bar which is tied just to the bare wire of the overhead service coming to the building. IIRC, my UPS unit hasn't indicated a grounding fault in the building.
My two main questions are 1) how should I ground the surge protector outside the building, and 2) how should I bond the antenna's ground rod to the building's (nonexistent) ground?
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"thats what i need, a digi cam for when i need to take pictures. im not going to go around taking photos and stuff." Julio |
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 Killa200Premium
join:2005-12-02
Southeast TN | Yikes! I think i would be introducing an option 3) Getting proper grounding for the building and then tying off the ground from the antenna's ground rod to that. Use at least #6 AWG to tie the rods together. Going from there since the appropriate place for the surge protection on the cat5e is at the entrance into the building, i would tie it to the grounding system located there (I.E. your new rod).
Right now you have no ground fault as your utility service bare neutral is doing its job.... its a very VERY nasty picture to watch what happens when it fails and there is no other path for the neutral or ground to follow... |
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| reply to pacmanfan
Killa200 is right.
You need to get proper grounding at the house. This means an electrician needs to be consulted.
Then you need to install an 8-foot ground rod at the pole 30-inches below grade where your antenna is, and use bare #6 buried 30-inches below grade to connect your new rod to the rod at the house. At the pole bond your antenna mast and surge protection to the rod, and at the house bond your POE LPU to the new rod at the house.
Now that I think about it depending on code requirements at the house you might have to install two rods for the electrical service. Again, the electrician will know what is or is not required here. The electrician will also make sure the house system is tied to the new ground system to ensure equipotential between everything.
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lutfulPremium
join:2005-06-16
Ottawa, ON Reviews:
 ·TekSavvy DSL
| reply to pacmanfan
said by pacmanfan:I have an antenna mounted 12' high on a wooden pole, located about 80' from the house that's powering the radio. You could deploy a solar-powered dual-radio (CPE+AP) on that pole until their grounding issue is resolved.  |
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robbinPremium,MVM
join:2000-09-21
Leander, TX
kudos:1 | reply to pacmanfan
Most of the homes I service have no ground rod. We are in the country and there is no code authority. It is easy for others to say "install a ground rod or two". In my case, this means using a rock drill and expensive materials to fill the hole (solid rock). I know how solid it is because I have drilled over 8 feet into it. What I do is install as you normally would and connect the ground to the ground buss in the breaker box which is connected to the utility neutral -- assuming that this is the first service disconnect then neutral and ground can be combined at that point.
If it is easy to drive a ground rod then you can advise the owners of the home to do so, but you will need to get an electrician to connect it as the entire house needs to be grounded to it and the breaker panel may have to be rewired.
As far as the antenna ground rod -- is this a rural home? If so, the ground is probably coming from the ground on the utility pole where the meter is. That would be the best place to connect to. |
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| reply to pacmanfan
I've got an electrician scheduled to install a grounding rod, and a buss bar in the breaker panel tomorrow. It should be fairly straightforward to do so, in this particular location.
At first glance, it appears as if the bare ground wires on all runs coming into the breaker panel have been cut back, and they're only using hot and neutral wires on the 120v circuits. I just need to make sure that the bare wire is connected to ground on any circuits my equipment is on, right? Or, do ALL circuits in the house need to be connected to the new grounding bar, as robbin mentioned?
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"thats what i need, a digi cam for when i need to take pictures. im not going to go around taking photos and stuff." Julio |
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Killa200Premium
join:2005-12-02
Southeast TN | all circuits in your panel should be grounded to a common point in the panel. That common point depending on where the primary service disconnect is located.
How old is this home again? Its been a while since NEC allowed non grounded circuits |
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| Built in the 70's, I think. |
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public
join:2002-01-19
Santa Clara, CA | reply to robbin
said by robbin: In my case, this means using a rock drill and expensive materials to fill the hole (solid rock). I know how solid it is because I have drilled over 8 feet into it. What I do is install as you normally would and connect the ground to the ground buss in the breaker box which is connected to the utility neutral -- assuming that this is the first service disconnect then neutral and ground can be combined at that point. A ground rod in dry limestone is not very effective, even with chemical fill.
A better solution would be ufer ground with bonds to any available buried metal.
What happens if one of the houses is struck by lightning? |
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robbinPremium,MVM
join:2000-09-21
Leander, TX
kudos:1 | said by public:[A ground rod in dry limestone is not very effective, even with chemical fill. A better solution would be ufer ground with bonds to any available buried metal. What happens if one of the houses is struck by lightning? Do you have any experience with ERICO’s Ground Enhancing Material GEM
That is what I have used and it is not just a chemical fill. However it is very expensive (both for the material and to rent the equipment to drill the hole, not to mention the labor). As to what happens if a house is struck by lightning, same thing as always happens. Read what I said and think about it, NONE of the houses are properly grounded mainly because the original contractors had no idea how to do it in solid limestone. We actually have the same problem with the electric coop -- as none of their poles are grounded well either. End result -- lightning strikes 1/4 mile away and it takes out several houses electronics.
All of my clients have either had lightning damage in their home or they know someone who has. Still, to bring in a piece of equipment to drill into the rock and then install a ground rod with GEM is not something most want to do. Basically all of the houses in my area rely on the power pole ground wire!  |
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| reply to pacmanfan
> I've got an electrician scheduled to install a grounding
> rod, and a buss bar in the breaker panel tomorrow.
That earth ground must also connect to incoming cable and telephone (installed for free surge protector). Better is how it is wired. If up over the foundation and down, that is sufficient for safety code but too long for surge protection. Better is to route the earth ground wire through foundation and down since every foot of wire shorter and with less bends means better earthing.
If the electrician only understands the safety code, then he will not understand this. If he also understands appliance safety, then he will also understand why better earthing keeps that wire away from the other wires.
Your UPS does not report earth ground. It is reporting safety ground. However if ground wires are cut back as you have described, then the UPS is reporting a ground that is incidental (not sufficient). I have seen many breaker boxes where the owner cut off all those safety ground wires in some myth that they were unnecessary or dangerous. Amazing how many 'know' simply on myths.
Now for the antenna. Treat the antenna and house as separate structures. Each must have its own single point earth ground. Any wires in any cable entering the structure must connect to that earth ground either directly or via a surge protector. A professional's application note entitled "Need for Coordinated Protection" demonstrates the concept:
»www.erico.com/public/library/fep···r002.pdf
To make both earth grounds even better, a bare buried ground wire interconnects both structure grounds.
A surge protector does not stop or absorb surges. To be effective, the protector connects each wire in each cable 'less than 10 feet' to a single point earth ground. That is the earth ground your electrician will be installing (which is why that ground wire is better routed shorter through the foundation, no sharp bends, separated from other wires, etc). The ethernet protector also must make a short (ie 'less than 10 foot') connection to that same ground rod. Best is for all earth ground wires to be separate until they all meet at a common earth electrode.
Similar ethernet protector would be earthed at the antenna. Earth is the protection. A protector is only as effective as the earth it connects to.
Meanwhile, the electrician should also install a 'whole house' protector on AC mains. This also is made effective by the earthing electrode he will be installing. Only the more responsible companies sell 'whole house' protectors. Names every electrician knows such as Square D, General Electric, Siemens, Cutler-Hammer, Intermatic, Leviton, etc. A Cutler-Hammer 'whole house' protectors (sufficiently sized) sells for less than $50 in Lowes. You want him to install that 'whole house' protector so that protection exists for every household appliance including more critical appliances such as bathroom GFCIs, smoke detectors, and the furnace. |
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lutfulPremium
join:2005-06-16
Ottawa, ON Reviews:
·TekSavvy DSL
| reply to robbin
said by robbin:Still, to bring in a piece of equipment to drill into the rock and then install a ground rod with GEM is not something most want to do. Ask SAE who does a lot of difficult grounding projects - I think they will suggest a horizontal grounding mesh embedded in thin layer of Conductrete over the limestone - no need to drill down.
»www.saeinc.com/ConducreteConductiveCement |
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robbinPremium,MVM
join:2000-09-21
Leander, TX
kudos:1 | OK -- so we rent a rock saw instead of a rock drill. Not that much difference in price. But I can tell you that the limestone gets very dry at the surface. Personally I would rather have some connection deeper in the earth. |
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Mike_27Premium
join:2004-05-15
Gardiner, MT | what about their well casing?
Mike |
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